Everything You Need to Know About Custom Format#

1. Introduction to Custom Format#

What Is Custom Format#

Custom Format is a feature that lets you teach Mergado to recognize and process virtually any XML or CSV file. It allows you to load any feed into Mergado, define its structure, and then work with the data just like with standard integrated formats. It also lets you create an output feed in Mergado in a format that is not among the official integrations.

You define the Custom Format yourself – you describe to Mergado which elements it should import or export and how to handle them. This functionality is intended mainly for less common, modified, or machine-unrecognizable formats that Mergado would not be able to load without your definition.

What It Is Used For#

Custom Format has several key uses:

1. Customizing Input and Output#

It allows you to adapt the data structure to your needs – both on the input and output side of the project.

2. Greater Control Over Data#

It helps you precisely determine how product data should be processed, displayed, and exported in Mergado.

3. Importing Unknown Feeds#

Suitable when working with formats that Mergado does not recognize: supplier feeds, outdated or heavily modified structures, custom feeds, or supplementary feeds (e.g., inventory, travel offers, reviews).

4. Preserving the Original Feed Structure#

If the input XML contains individual products directly after the root element, Custom Format lets you preserve the original structure without modifications – useful for unstable supplier sources.

5. Exporting to a Custom Format#

Also used for creating an output feed in a format that Mergado does not yet officially support. This is typical when expanding to new marketplaces or for smaller comparison engines. You just need a sample feed template containing at least one example item.

How Mergado Works with Data (Mergado XML and Converter)#

Mergado XML#

All data conversions in Mergado go through a unified intermediate format called Mergado XML. It serves as a “universal language” into which input data is converted, and from which output formats are then generated.

Converter#

The converter is a mechanism that translates data between formats. It is used whenever the input and output formats differ. The converter is also activated in cases where both the input and output are in Google Merchants format.

Role of Custom Format#

Custom Format lets you create your own converter. When defining a Custom Format, you explain to Mergado what each part of your feed means and what Mergado XML equivalent it should map to.

The most important step (applies only when working with XML feeds): correctly selecting elements for:

• CHANNEL (element name in Mergado XML)
  • the so-called Root, i.e., the root element wrapping all products in the XML feed
  • there is only one such element in the XML feed,
  • typically its opening tag is at the very beginning of the feed and its closing tag at the very end
  • the root element name can differ in each feed, examples by format:
    • Google:
    • Heureka
    • Mergado XML
• ITEM (element name in Mergado XML)
  • the element wrapping one item (product)
  • there are as many of these elements in the XML feed as you have items/products,
  • each product/item has exactly one wrapping element
  • the product wrapping element name can differ in each feed, examples by format:
    • Google:
    • Heureka
    • Mergado XML

These two elements define the structure in which Mergado processes data.

When It Makes Sense to Use Custom Format#

On Input#

• Mergado does not recognize the feed format.
• You are working with an unknown, modified, or custom format.
• You need to preserve the original feed structure.
• You are connecting supplementary data that is not integrated (inventory, services, reviews).

On Output#

• You need a feed in an unsupported format.
• You want control over the root elements and output XML structure.
• You have a sample feed from which a template can be created.

Limitations and Things to Watch Out For#

1. Ignoring Elements Outside ITEM#

Custom Format cannot process elements located above the item wrapping element. Everything that is not under ITEM is invisible to the Editor for feeds processed via Custom Format. This means information placed between CHANNEL and ITEM may be lost.

Solution for complex structures: split the feed into two projects and rejoin them using the Blending Bull extension.

2. Conversion May Cause Data Loss#

The converter is applied even when converting from the same Custom Format to the same one. If the mapping is not complete, information may be lost in the new feed (it remains in the original feed – Mergado simply does not work with it).

3. Root Elements on Output#

Root elements are created automatically by Mergado Editor based on the chosen output format. They cannot be manually created as standard elements in the editor. If you need non-standard root elements in the output feed, the only way to influence them is by choosing the correct template for the Custom Format used on the output.

4. Need for Updates When Changes Occur#

If a new element appears in the input file, the Custom Format has no configured behavior for it. Mergado will automatically import such an element and will not hide it, so it automatically enters the output feed unchanged. In this case, you need to update the Custom Format structure and add mapping settings for the new element. After saving and regenerating the project, the changes will take effect automatically.

Alternatively, if new elements cause the output feed to become invalid, the quickest fix is to manually hide the new elements on the Elements page and run a project Export (without applying rules).

FAQ#

What is Custom Format in Mergado?#

Custom Format is a feature that lets you teach Mergado to process virtually any XML or CSV file, regardless of whether Mergado normally supports it. It lets you define which elements the feed contains and how the system should handle them during import and export. It also serves for creating an output feed in a custom format, for example, for platforms or channels that Mergado does not support by default.

What is Custom Format used for?#

Custom Format lets you adapt the project’s data structure to your needs. It helps you precisely control how Mergado loads, displays, and exports product data. It is especially useful for importing non-standard or modified feeds and for exporting to formats not included among integrated channels.

When does it make sense to use Custom Format on input?#

Custom Format is suitable when Mergado cannot recognize the feed or when you are working with a custom, modified, or supplementary feed that does not fit existing integrations. It also helps when you need to preserve the original feed structure if the XML contains items directly under the root element. You can also use it for supplementary input data such as inventory, services, or reviews.

When does it make sense to use Custom Format on output?#

Custom Format on output is useful when you need to create a feed in a form that Mergado does not generate by default. This is often about expanding to new platforms or connecting to internal systems with their own XML structure. You just need a sample feed from which Mergado will create the output template.

What is Mergado XML and why is it important?#

Mergado XML is an internal intermediate format through which all data conversions pass. It works as a “universal language” into which input data is translated, and from which output formats are generated. This means there does not need to be a separate converter for each format pair.

What does the converter do?#

The converter translates values between data formats – from any input to Mergado XML and from there to the output format. For selected formats (e.g., Google Merchants), it is activated even when the same format is on both input and output. If the mapping is not complete, the converter may omit some values, which is why paying attention to mapping is recommended.

What role does Custom Format play in data conversion?#

Custom Format lets you create a custom converter tailored to your feed. You precisely specify what individual elements mean and how they should be converted to Mergado XML. This gives you control over data structuring even across platforms that Mergado does not natively know.

What does it mean to correctly select CHANNEL and ITEM?#

CHANNEL is the root element of the Mergado XML feed and determines where the entire document begins and ends. ITEM is the wrapping element for one item and appears in Mergado XML as many times as you have products. Correct mapping of these two elements is a fundamental prerequisite for Mergado to process your feed. CSV feeds do not have these elements, so mapping them is not needed.

What limitations does Custom Format have?#

Custom Format cannot process elements that lie outside ITEM, for example, information placed between CHANNEL and ITEM. Mergado ignores these elements and they cannot be worked with directly in the project. If you need to preserve them, a different approach is required, such as the two-project model and merging via Blending Bull.

Why can data loss occur during conversion?#

Custom Format ignores elements in XML feeds that are located between CHANNEL and ITEM. If such elements contain information you need, a different approach is required, such as the two-project model and merging via Blending Bull.

How does Mergado handle root elements on output?#

Root elements are created based on the chosen output format and cannot be directly edited. If you need a different structure, you need to use a Custom Format created from a sample feed, or modification via Blending Bull. This ensures the output feed has exactly the header and wrapper you require.

What should I do when a new element appears in the input feed?#

The new element is automatically imported into the project, but Mergado does not know what to do with it because it is not part of the original mapping. In this situation, you need to update the Custom Format structure and add mapping for the new element. Then you regenerate the project and the data will be loaded and converted correctly.

How do I know when it is better not to use Custom Format?#

Custom Format is not needed where an official integration exists. If you have doubts, it is advisable to consult support.

What is a sample feed for?#

A sample feed serves as a template when creating an output Custom Format. Mergado uses it to determine the root element structure, wrapping tags, and other elements that should be preserved in the output. A minimal example is sufficient – even just one product. The sample feed must be available at a URL address.

How do I know the Custom Format is configured correctly?#

You can tell the format is correctly defined when the project loads all necessary elements and the output feed has the expected structure. The critical point is correct mapping of CHANNEL and ITEM, as well as the pairing element in the project. If the output data matches the required template and no information is lost, the configuration is fine.

What should I do if creating a project with Custom Format results in an error?#

Check the Custom Format mapping. A common mistake with XML feeds is incorrectly mapped root element or item wrapping element. Both elements can only be mapped once, to one element in your feed. Another common mistake is a poorly chosen pairing element. The safest choice is an element with product IDs, combined with, e.g., an element with EANs or product/image URLs. If you are unsure how to set up the Custom Format correctly, it is advisable to consult support.

2. Where Custom Format Can Be Created and Managed#

In Mergado, you can define a Custom Format in two ways: directly when creating a project, or in a dedicated section for working with custom formats. Both approaches complement each other and allow you to create and later reuse any format definition.

Definition During Project Creation#

When creating a project, you can specify a Custom Format for both the input feed and the output feed. This option appears whenever Mergado cannot assign any integrated format to the input file, or when you need to create a specific output.

Custom Format on Input#

You access Custom Format creation for the input feed in step 3 of the project creation wizard. If the system recognizes the connected feed’s structure, it offers the option to change the detected format using the Select different format button, and then you can either choose another official format from the dropdown, or create a Custom Format for the input feed using the Define custom format button.

If the system does not recognize the connected feed’s structure, it offers the option to either manually select an official format from the dropdown, or create a Custom Format for the input feed using the Define custom format button.

When creating a Custom Format for the input feed, the system offers two approaches:

• Simplified walkthrough – suitable for quick setup of the basic structure.
• Detailed settings – allows detailed mapping of all found elements.

Both methods lead to the same goal: determine where the feed starts, which elements represent individual products, and which element contains a unique value across all products.

For correct processing of the input feed, you need to map at least:

• the root element (CHANNEL),
• the product wrapping element (ITEM),
• the product identifier (ITEM_ID) – an element with a unique value for each item.

Of course, you can also map all elements from the input feed, which can simplify subsequent work (for example, reducing the number of rules needed). However, this is not necessary for data import itself.

Custom Format on Output#

You access Custom Format creation for the output feed in step 4 of the project creation wizard. Use the Define custom format button. In the next step, you need to enter the URL of a sample feed – a template based on which the Custom Format will be set up and the output feed will be created.

Note: The sample feed cannot be uploaded via Upload – a URL address is required. If you have the template as a file, create a URL address using cloud storage, e.g., Dropbox, or you can use the Mergado Files extension.

If you already have a Custom Format prepared, you can select it as the project’s output format. This determines what the final XML or CSV will look like, regardless of whether Mergado normally supports the format. If the format was created from a sample feed, Mergado preserves the root elements and their arrangement.

When creating a Custom Format for the output feed, the system offers only one approach:

• Detailed settings – allows detailed mapping of all found elements.
• Simplified walkthrough is not available here

For correct output feed creation, you need to map at least:

• the root element (CHANNEL),
• the product wrapping element (ITEM),

In this case, Mergado will prepare the output feed, create all elements from the template into the project, but since it does not know what individual elements mean, the elements will not be populated and need to be set up manually using rules.

Of course, you can also map all other elements from the sample feed, which can simplify subsequent work (for example, reducing the number of rules needed).

“Custom Formats” Section in the Main Menu#

Standalone custom format management can be found in the left menu of Mergado Editor in the Custom formats tab when you are at the user level (the left menu changes depending on whether you are managing a user, an online store, or a project). This section serves as a central place for working with all formats created in the account.

Here you can:

• create a new format without connection to a specific project,
• enter a URL of a sample file (example feed),
• perform element mapping,
• edit or re-analyze an existing format.

This section serves as a central place where you can maintain, test, and prepare custom formats for use in future projects.

Reusing Custom Formats#

Once you create a Custom Format – whether in the wizard or in the standalone section – it is saved in Mergado and you can use it indefinitely:

• on input, if you want to process another feed with the same structure,
• on output, if you need to generate a new feed in the same form.

If you already have at least one saved Custom Format, the Pre-fill from function is available when creating a new Custom Format. It lets you inherit the structure (configured mapping) of an existing format. This speeds up work when you are dealing with multiple formats that have a similar schema.

FAQ#

Where can I create a Custom Format in Mergado?#

You can create a Custom Format in two ways – directly when creating a project or in the standalone Custom Formats section in the left menu. Both methods complement each other and let you prepare a format either quickly during project work or in advance. After saving, the format is available for repeated use in all projects.

How do I create a Custom Format on input when creating a project?#

In step 3 of the project creation wizard, Mergado offers Custom Format creation when it does not recognize the feed structure or when you manually select “Select different format.” You can then use either the simplified walkthrough or detailed settings. You need to map CHANNEL, ITEM (for XML feeds), and ideally also the product identifier so the project can correctly work with items.

What is the minimum that needs to be mapped for Mergado to load the feed?#

For minimum functionality, you need to map CHANNEL, ITEM (for XML feeds), and one element with a unique value (most commonly ITEM_ID). This is enough for Mergado to identify the document start, individual products, and their unique key. Other elements can be added later.

How do I create a Custom Format on output?#

It is created in step 4 of the project creation wizard using the Define custom format option. You need to enter the URL of a sample XML file (example feed), based on which Mergado will build the output structure. Then you map at least the basic elements and save the format for use in the project.

Why must the sample feed be available at a URL address?#

Mergado creates the output format exclusively from a file available via URL because it needs to import the structure during analysis. File upload is not supported. If you do not have your own hosting, you can use a cloud service (Dropbox, OneDrive) or create the file using Mergado Files.

Why is the simplified walkthrough not available for the output format?#

Only detailed settings are available for the output format. This is intentional because the target structure comes from a sample feed and full control over the conversion to the template is needed. Simplified mapping might not be precise enough for output.

What happens if I map only the minimum when creating the output format?#

Mergado will create the output feed with root elements from the template and create empty elements in the project based on the template, but elements without mapping will not be populated with any values. These values then need to be added manually using rules. Therefore, it is advisable to add mapping for as many elements from the sample feed as possible.

What is the “Custom Formats” section in the left menu for?#

This section is for central management of all custom formats in the account. Here you can create new formats, edit existing ones, and update their structure. It is the most suitable place for preparing formats that you will use repeatedly in the future.

Can one Custom Format be used in different projects?#

Yes, every saved Custom Format is available for repeated use. You can use it on input and output in any number of projects. This is especially useful when working with multiple feeds that share the same structure.

What is the “Pre-fill from” option for when creating a new format?#

It lets you inherit the structure (element mapping) from a previously created Custom Format. It is ideal when working with multiple formats with the same or similar schema. This way, you do not have to start from scratch with each new format.

3. Simplified Walkthrough vs. Detailed Settings When Defining Custom Format#

When creating a Custom Format on input as part of the new project creation wizard, you can work in two ways: either use the simplified walkthrough or switch to detailed settings. Both approaches serve the same goal – explaining the feed structure to Mergado – but they differ in the level of control and number of options they offer the user.

The simplified walkthrough is suitable for quick feed processing. Detailed settings provide full control over element mapping and format configuration.

Simplified Walkthrough#

The simplified walkthrough appears only when creating a Custom Format on input within the new project creation wizard. The wizard offers the user a quick path to define the basic structure. The goal is to simplify Custom Format setup for new users by offering mapping of only the most important elements and hiding advanced settings that can be changed later.

When It Is Used#

• Within the new project creation wizard when setting up the input feed format.
• You want to create functional mapping as quickly as possible.

What the Simplified Walkthrough Offers#

• Display of basic elements in a clear format.
• Highlighting of key elements used by advertising channels.
• More understandable element names compared to the technical view.
• Smart mapping that attempts to automatically assign elements by name and meaning.

How Smart Mapping Works#

The system suggests pairing – e.g., description –> DESCRIPTION, EAN –> EAN, ID –> ITEM_ID. The user then just checks the suggestions are correct and optionally adjusts individual choices.

When the Simplified Walkthrough Is Ideal#

• When you need to start working with data quickly.
• When the feed structure mostly follows common conventions.
• When it is a one-time or less complex mapping task.

2. Detailed Settings (Complete Custom Format Definition)#

Detailed settings is the full version of the interface for defining a Custom Format. It contains all options available for element mapping.

When It Is Used#

• The feed has a complex or atypical structure.
• You need to precisely control how each element is processed.
• You are preparing a format for repeated use or for an output feed.
• You need to define the meaning of sub-elements, variants, or parameters.

What Detailed Settings Include#

1. Custom Format Parameters

General configuration that determines format behavior:

• appropriate format name,
• country setting (affects currencies),
• option to inherit settings from an existing format,
• option to split variants into separate products,
• definition of a custom category tree.

2. Data Processing Settings (Element Mapping)

The key part that determines how Mergado interprets individual feed parts.

Essential elements:

• root element (e.g., CHANNEL),
• product wrapping element (e.g., ITEM),
• product identifier (e.g., ITEM_ID) – an element with a unique value for each item.

Additional options:

• direct mapping to Mergado XML,
• operations for elements without sub-elements (Pass as is, Hide, Element meaning),
• special operations for wrapping elements (e.g., DELIVERY, PARAM, VARIANT),
• ability to map any number of elements for easier subsequent work in the project.

Comparison: Simplified Walkthrough vs. Detailed Settings#

Which Approach to Choose#

• Use the simplified walkthrough if you need to quickly create a project and the feed has a relatively straightforward structure.
• Choose detailed settings if you are working with a complex feed, preparing an output template, or need to precisely define the meaning of individual elements.

FAQ#

What is the simplified walkthrough when creating a Custom Format?#

The simplified walkthrough is a variant of the interface in step 3 of the wizard that offers only the most important elements and a faster path to creating functional mapping. It is designed so it does not overwhelm the user with advanced settings and enables a quick start even with unknown feeds. It offers smart mapping that automatically recommends element assignments by name and meaning.

When does the simplified walkthrough appear?#

It appears exclusively when creating a Custom Format on input, and only when Mergado does not recognize the feed structure or the user manually chooses to define a Custom Format. In these situations, the goal is to speed up basic setup so the project is ready to work with as soon as possible. Detailed settings can be invoked at any time.

How does smart mapping work within the simplified walkthrough?#

Smart mapping attempts to automatically assign elements by their name and typical meaning. The user just checks the suggested values and optionally adjusts which element should be linked to which Mergado XML equivalent. This step significantly speeds up work, especially with common or simpler feed structures.

When is it appropriate to use the simplified walkthrough?#

The simplified walkthrough is ideal when you need to start working with data quickly and the feed has a fairly standard structure. It is also suitable for one-time processing or when you do not want to deal with detailed settings right away. If the feed does not contain complex hierarchy, this variant is often sufficient.

What are detailed Custom Format settings?#

Detailed settings is the full variant of Custom Format creation that allows mapping individual elements and their sub-elements with maximum precision. It also contains all format parameters such as country, name, or variant splitting, and allows defining behavior of more complex structures. This approach is intended for feeds with multiple levels or for output formats being prepared.

When is it appropriate to use detailed settings?#

Detailed settings is the best choice when the feed contains a complex, non-standard, or multi-level structure. It is also appropriate when you need completely precise control over how data will be processed and exported in the project. It is also essential when preparing a format that will be used repeatedly or on output.

What elements must be mapped in both cases?#

Whether you use the simplified walkthrough or detailed settings, you always need to specify the root element (CHANNEL) (applies to XML feeds), the product wrapping element (ITEM) (applies to XML feeds), and at least one product identifier (most commonly ITEM_ID). These elements are key for Mergado to correctly load the data feed and identify individual items. Mapping of other elements depends on what you will need in the project.

What does detailed settings offer beyond the simplified walkthrough?#

Detailed settings allows defining the meaning of every element and setting special operations for elements with sub-elements, such as parameters, shipping, or variants. It also contains all format parameters and offers the option to inherit structure from an existing Custom Format. It thus provides the highest possible data conversion accuracy.

Which approach to choose – simplified or detailed?#

Choose the simplified walkthrough when it is about quick project creation and the feed has a simple and readable structure. Use detailed settings if you plan to work with the data long-term, or if the feed is complex and requires precise mapping. The choice depends primarily on data complexity and whether speed or accuracy is more important to you.

Can the simplified walkthrough replace detailed settings?#

Yes, in many simpler cases it is sufficient. However, if the feed contains variants, parameters, multi-level structure, or you plan further exports, detailed settings will be more precise and stable in the end. It is therefore recommended to start with the simplified approach and switch to detailed mode if you find more control is needed.

4. Creating a Custom Format – Detailed Settings#

Detailed Custom Format settings is the step where you precisely tell Mergado how to interpret your feed structure. Based on this information, a converter between your data format and Mergado XML is created. This phase follows the analysis of the source file structure.

Feed Structure Analysis#

When creating a Custom Format, Mergado first loads and analyzes the connected file. From its structure, it determines which elements can be mapped and creates an overview of them.

What the Analysis Does#

• loads the XML or CSV structure from the given URL,
• identifies available elements and their structure,
• prepares a list of elements that can be mapped to Mergado XML.

Structure Update#

If a new element appears later in the input file, it needs to be added to the Custom Format settings. The Update structure from file option loads new elements and lets you specify how they should be propagated into Mergado.

Setting Basic Custom Format Parameters#

In this section, you set general format parameters. These options do not concern individual elements but the behavior of the format as a whole.

Available Parameters#

Element Mapping (Data Processing Settings)#

This section determines how Mergado will interpret your feed elements. Mapping defines the relationship between a specific element and its equivalent in Mergado XML.

Required Elements (applies only to XML)#

For functional feed processing, at least these two elements must be mapped:

• CHANNEL – the root wrapper of the entire feed,
• ITEM – the wrapping element for one item.

Without these two elements, an XML feed cannot be imported.

Recommended Elements#

Mergado allows mapping any number of additional elements. The more elements you map, the less work you will have later with rules, and the better the feed can be converted to other output formats.

Operations for Simple Elements#

For elements that do not have sub-elements, three types of operations can be used:

Operations for Wrapping Elements#

For elements that contain further structure, special operations can be chosen that enable settings for their sub-elements.

Examples:

• DELIVERY – you set the shipping price, carrier name, or code,
• PARAM – product parameter definition,
• VARIANT – working with individual item variants.

Mapping Impact#

• More extensive mapping makes subsequent export to other formats easier.
• Minimal mapping requires more work in rules (copying and adding values).
• Elements located outside ITEM cannot be processed – Mergado ignores them.

FAQ#

What does feed structure analysis mean when creating a Custom Format?#

Analysis is the first step in which Mergado loads the file from a URL and identifies all available elements. From their hierarchy, it builds a structure that is then offered for mapping. This process determines what can be worked with in the Custom Format.

What should I do when a new element appears in the input feed?#

You need to open the saved Custom Format definition and use the “Update structure from file” option. This loads the new element into the list and you can specify how it should be processed in Mergado. After saving and regenerating data, the new element becomes part of the project.

What are basic Custom Format settings for?#

These parameters determine the behavior of the format as a whole and do not address individual elements. They include the format name, country setting, option for working with variants, or activation of a custom category tree. Correct parameter settings simplify future use in other projects.

Why is it important to correctly name the Custom Format?#

The format name is displayed in the format list and helps with orientation, especially when you have multiple formats. A well-chosen name lets you quickly identify what type of feed the format was created for. This prevents errors during repeated use.

How does the “Pre-fill from” option work?#

This option makes existing custom formats available and lets you inherit their structure. It is useful when you need to create a similar format or work with feeds that have the same schema. This way, you do not have to map everything from scratch.

What do the “Pass as is,” “Hide,” and “Element meaning” operations mean?#

• “Pass as is” - The element is imported and exported without changes, unless the Converter rule or user sets it as hidden.
• “Hide” ensures the element is imported and set as hidden. It can be used within rules, for creating queries, or optionally unhidden manually.
• “Element meaning” is used for mapping the element to a Mergado XML equivalent.

When is it worth mapping additional elements beyond the required ones?#

If you plan to export to other formats or will work with data in rules, detailed mapping is significantly beneficial. Fewer mapped elements means more work when adding values in the project. The more precise the mapping, the simpler the further processing.

How do special operations for wrapping elements work?#

They are used when an element has its own nested structure, such as parameters, shipping, or variants. By selecting a special operation, you enable settings for their sub-elements. This allows you to define in detail how the values of these structures should be processed.

Why does Mergado ignore elements outside ITEM?#

Custom Format can only work with the part of XML that consists of individual product items. Elements above ITEM, such as information between CHANNEL and ITEM, are not part of the product data model. Therefore, they are ignored during import and the project has no control over them.

How do I know the mapping is sufficient?#

If you can load the feed, work with data without needing extensive rules, and the export has no information loss, the mapping is set correctly. The critical point is capturing all elements you will later edit or export. If you frequently need to add values using rules, the mapping is probably too brief.

What is the relationship between mapping and the converter?#

You define the mapping, and the converter converts data to Mergado XML based on it. If you do not map an element, the converter “does not know” about it and does not work with it. Good mapping therefore determines the quality of the entire converted feed.

5. Custom Format on Input#

Custom Format on input is used for loading data feeds that Mergado does not recognize and converting them to the internal Mergado XML structure. This allows processing virtually any XML or CSV file in Mergado.

When Custom Format on Input Is Used#

The need to define a Custom Format arises when the system cannot determine the input feed structure and displays information that the format is unknown. In this situation, it offers to create a Custom Format.

Typical Scenarios#

• Supplier feeds or otherwise structured XML/CSV,
• Custom feeds made to order. Typically for larger online stores.
• Outdated or heavily modified variants of known formats,
• Supplementary feeds, such as inventory or service feeds,
• Feeds providing other types of services (reviews, travel offers).
• etc.

Steps for Creating a Custom Format When Importing a Feed#

Custom Format definition takes place in step 3 of the project creation wizard.

1. Create a new project and enter the input feed URL.
2. If Mergado does not recognize the structure, choose Define custom format.
3. Map the required elements:

• CHANNEL
• ITEM

4. Map additional elements you will work with in the project (URL, NAME, ITEM_ID, …).
5. Name and save the format.
6. In step 4, you can

• Keep the same Custom Format on output as well, so the feed structure will not change.
• Use the dropdown to select another official format, e.g., Google, Meta, etc.
• Create a new Custom Format for output.

7. In the last step, verify that pairing elements are selected. If not, they need to be configured.

Pairing Element Configuration#

The pairing element is a key piece of data that Mergado uses to uniquely identify each item in the project.

What Is Important:

• It must have a unique value for each product.
• Most commonly, the element with product IDs or another unique identifier (URL, EAN, …) is used.
• In the summary step, you need to verify the pairing element is correctly selected.

The pairing element works like a “national ID number” for each item. It lets Mergado safely track and process individual products regardless of how their values change during work.

How Many Elements to Map#

Minimum – for Functionality#

For import, mapping only the required elements (CHANNEL, ITEM, and optionally ITEM_ID) is sufficient.

Maximum – for Efficiency#

Mapping more elements means simpler work in subsequent project steps.

Benefits of detailed mapping:

• fewer rules needed for copying values,
• faster conversion to other output formats,
• better readability and project stability.

Impact example: If you do not map the product name element, you will have to add it later to the format using a rule. If you map it during the Custom Format definition, Mergado will then correctly convert it to the output feed automatically.

Updating structure when the feed changes#

If new elements appear in the input feed, the saved Custom Format will not automatically pick them up. You need to:

1. Open the Custom Format
2. Click Update structure from file.
3. Assign processing methods to the newly found elements.
4. Save and regenerate projects using this Custom Format.

This ensures consistent feed processing even after changes.

FAQ#

When is it necessary to use Custom Format on input?#

You use Custom Format when Mergado cannot recognize the input feed structure and displays information that the format is unknown. Typically these are supplier, custom, outdated, or heavily modified feeds. In these situations, you need to explain the data structure to Mergado so it can process them.

What types of feeds most commonly require Custom Format on input?#

Most commonly these are supplier and custom feeds that have no public specification or differ from standards. This also includes supplementary feeds such as inventory, service, or feeds containing services like reviews or travel offers. Custom Format is also used for modified or outdated versions of otherwise known formats.

How does creating a Custom Format during import work?#

Creation takes place in step 3 of the project creation wizard, where you choose “Define custom format.” Then you map the required elements CHANNEL and ITEM (for XML feeds) and other items you will work with in the project. Finally, you save the format.

What is a pairing element and why is it so important?#

The pairing element is data that lets Mergado uniquely identify each item. It must have a unique value for each product – most commonly ITEM_ID, URL, or EAN. Without a correctly configured pairing element, the feed cannot be imported correctly or changes properly paired.

How many elements should be mapped when defining a Custom Format?#

For basic functionality, mapping CHANNEL, ITEM (for XML feeds), and one unique identifier is enough. However, if you want to minimize later work, it is advisable to map additional elements as well, since this simplifies work with rules and makes conversion to other output formats easier. Detailed mapping improves project stability and clarity.

What happens if I do not map some important elements?#

Unmapped elements will appear in the project, but Mergado will not be able to use them correctly and they will need to be added manually using rules. This leads to higher workload and can cause errors during export. Precise mapping therefore significantly simplifies later work.

How should I proceed when new data fields appear in the input feed?#

You need to open the Custom Format definition and use the “Update structure from file” option. Mergado will load the new elements and you assign processing methods to them. Then you regenerate the project for the changes to take effect.

Can Custom Format be used even when Mergado recognizes the format?#

Yes, in some cases it may be advantageous to create a Custom Format even for a recognized feed, for example, if you want to preserve the original structure or need to work with elements that the standard converter does not take into account. In this case, simply choose “Select different format” and then define your own.

What should I do if I am not sure the Custom Format is configured correctly?#

It is recommended to check the loaded elements, pairing element, and the project’s output feed structure. If you see all the values you need to work with and data pairs correctly, the format is fine. If you encounter issues, it is better to go back to mapping or contact support.

6. Using Custom Format on Output#

Custom Format on output is used so that Mergado can generate a product feed in a structure it does not support by default. It is suitable anywhere you need the output file to exactly match the specific requirements of a platform, system, or internal processes.

When Output Custom Format Is Used#

You will primarily use an output Custom Format in situations where:

• you need a feed for a platform not integrated in Mergado,
• you are creating a connection to a new e-commerce channel,
• you work with smaller comparison engines or internal systems with their own data structure,
• you need to achieve a specific root element structure (e.g., …).

Output Custom Format lets you define the output feed appearance so it exactly matches the required format.

What Is a Sample Feed and Why Is It Needed#

An output Custom Format is created based on a sample feed – a sample XML or CSV file containing at least one item.

Why the Sample Feed Is Important#

• It serves as a template that Mergado uses to learn what the final feed should look like.
• It defines the root elements you want in the target structure.
• It can be entirely fictional – a single fictional item is sufficient; the actual values do not matter.

Sample Feed Requirements#

• must be available at a URL address,
• must contain the root structure you want in the output,
• can have minimal content, for example:

<?xml version="1.0" encoding="UTF-8"?> <PRODUCTS> <PRODUCT> <ID>1</ID> </PRODUCT> </PRODUCTS>

How to Create a Sample Feed#

There are two ways:

1. Manual File Creation#

• prepare the XML in a text editor, or CSV in a spreadsheet editor,
• save it on a server,
• make it accessible at a URL address.

2. Using the Mergado Files Extension#

• activate the Mergado Files extension,
• create a new file,
• paste a sample item, which you can obtain, for example, from comparison engines,
• save it as XML or CSV,
• you get a URL to use when defining the format.

Mergado Files is ideal if you need to quickly edit or test the sample feed.

Steps for Creating a Custom Format on Output#

An output Custom Format is created either in advance in the Custom Formats section in the left menu at the user level, or directly during new project creation in step 4 of the wizard.

1. Open Custom Formats and click New custom format.
2. In the Source file field, enter the sample feed URL.
3. Name the format.
4. Map elements:

• the minimum is setting the root wrapping elements (CHANNEL, ITEM),
• it is recommended to map all elements you will generate in the output.

5. Save the format.

After saving, the Custom Format becomes reusable. In every project, it can be selected as the output (or input) format.

How Mergado Generates the Output Feed from a Custom Template#

The output Custom Format determines the final feed structure. When generating output, Mergado:

• uses root elements exactly as they were in the sample feed,
• uses the defined mapping to convert values from your input feed to the resulting format,
• preserves the order and structure of elements according to the template.

This allows you to quickly create any XML or CSV feed without needing Mergado to develop a new integration.

Mapping Efficiency#

Although mapping only the minimum is enough for the output feed, it is more beneficial to define mapping as thoroughly as possible:

• you gain better control over the result,
• you reduce the need for rules to fill in values,
• you enable easier reuse of the format in other projects.

FAQ#

When does it make sense to use Custom Format on output?#

You use Custom Format on output whenever you need a feed in a structure that Mergado does not offer by default. Typically this involves connecting to a new platform, a smaller comparison engine, or an internal system with its own structure. It lets you precisely control the output XML or CSV format, including root elements.

What is a sample (example) feed and what is it for?#

A sample feed is a sample XML or CSV file containing at least one item that matches the target structure you want to generate. Mergado uses it to load root elements, internal structure, and element order. It serves as the template for generating the output feed.

Does the sample feed need to be real, or can it be fictional?#

The sample feed can be entirely fictional – one item with minimal values is enough. What matters is that it has the correct element structure, not specific data. Values like ID, name, or price are just examples in this context.

Why must the sample feed be available at a URL address?#

Mergado loads the structure directly from a URL so it can use it as a source during analysis. File upload without a URL is not possible. If you do not have your own hosting, you can use cloud services or the Mergado Files extension.

How can I create a sample feed?#

Either prepare an XML or CSV in a text/spreadsheet editor and save it on a server with a public URL, or use the Mergado Files extension. In Mergado Files, create a new file, paste a sample item, save it in the correct format, and get a URL for use in the Custom Format. The second option is suitable if you need to modify the sample feed on an ongoing basis.

How does creating a Custom Format on output work?#

In the Custom Formats section, choose “New custom format” and enter the sample feed URL as the source file. After analyzing the file, name the format and map the needed elements, at minimum CHANNEL and ITEM. The saved format can then be selected as the output format in any project. Alternatively, you can create a Custom Format directly during new project creation in step 4 of the wizard by clicking Define custom format and entering the sample feed URL. After saving the Custom Format, you return to the wizard where the created Custom Format will be filled in as the output format.

How does Mergado use the Custom Format when generating the output feed?#

During export, Mergado starts from the template loaded from the sample feed, preserving its root elements and structure. Using mapping, it converts values from Mergado XML to the correct elements in the output. The result is a feed in the form that matches your requirements without custom programming.

What happens if I map only the minimum elements in the output format?#

Mergado will create the output feed with the correct structure, but elements will not be populated with data. Values of unmapped elements will need to be added using rules or other project settings. This approach works but is less efficient for long-term use.

Why is it worth mapping as many elements as possible on output too?#

Detailed mapping gives you better control over how data is written to the output and reduces the number of rules you have to create in the project. It also simplifies reuse of the same format in other projects. It is especially worthwhile when the format serves multiple clients or multiple online stores.

Can the output Custom Format also be used as input?#

Yes, once a format is created, it is available in the format list for both input and output. This can be useful, for example, for transformations between different internal systems or for data verification.

7. Working with More Complex XML Structures#

This section describes situations where the data feed contains elements placed outside the usual product structure, i.e., outside the ITEM element. For these feeds, Custom Format has certain limitations and alternative approaches need to be used.

Custom Format Limitations During Import#

Custom Format can only work with elements located inside the chosen item wrapping element (ITEM). Elements that are above it in the hierarchy or outside it are ignored by Mergado Editor.

Information Between CHANNEL and ITEM#

• Some XML feeds contain additional data levels between CHANNEL and ITEM (e.g., categories, shipping, metadata).
• These elements are not part of the item itself and therefore are not loaded during import.

Typical Examples of Problematic Feeds#

• XML feeds with global category information stored outside products,
• data sources where shipping information is defined at the CHANNEL level,
• complex feeds with multi-level structure between the root element and individual items.

Solution: Two-Project Model + Blending Bull#

If you need to preserve the entire XML feed structure, including elements outside ITEM, you can use a two-step approach:

1. First project – contains products.
2. Second project – contains supplementary information not part of ITEM.
3. Merging – output data from both projects is combined using the Blending Bull extension.

How the Two-Project Model Works#

Merging with Blending Bull#

1. Activate the Blending Bull extension.
2. In the Data Sources section, select outputs from both projects.
3. In the Files section, create a new output file and then select the created data sources from the previous step.
4. Add modifications using rules as needed.

Why This Approach Works#

Each project loads only the part of the structure that Mergado can work with. Blending Bull then lets you rejoin both parts and get the complete data output.

Editing Root Elements on Output#

Root elements of the output feed cannot be directly edited in Mergado. If you need a different wrapper element structure, there are two alternatives: editing via Blending Bull, or creating a custom template.

Editing via Blending Bull#

Blending Bull lets you work with the output feed as a text file. This allows editing:

• root elements,
• header,
• footer,
• element names.

Find and Replace Rule

Using rules in Blending Bull, you can make bulk element name changes. For example:

• SHOP –> PRODUCTS, SHOPITEM –> PRODUCT.

This makes it easy to modify the output structure without intervening in the project itself.

Alternatives to Blending Bull (for Output Structure Control)#

There are two other ways to influence the output structure:

1. Creating a Template Using Custom Format

• Use a fictional or existing feed with the desired root elements.
• Use this feed when creating a Custom Format on output.
• Mergado will then preserve root elements exactly as they were in the example feed.

2. Requesting a New Integrated Format

• If you have the target format specification, you can contact Mergado support.
• The format may be added among officially supported integrations.
• It can then be selected as a regular output format.
• However, adding a new format must go through a prioritization process and may take longer.

FAQ#

Why does Mergado ignore certain elements in the input XML feed?#

Custom Format can only work with elements located inside the item wrapping element (ITEM). Everything outside it – for example, elements between CHANNEL and ITEM – is not processed during import. This information is not part of product data and therefore the Editor does not see it.

How do I know the feed is problematic and requires a special approach?#

The simplest approach is to open the output feed and compare it with the input feed. Typical examples are feeds where categories, shipping, or other metadata are placed at the CHANNEL level or in several layers above ITEM. If important data is missing after import, it is a sign that it is located outside the structure Mergado can load. In such situations, an alternative approach is needed.

What is the two-project model and when should I use it?#

The two-project model is used when you need to preserve or process parts of the XML feed that do not belong under ITEM. One project loads products and the other loads supplementary information. Then both outputs are merged using the Blending Bull extension.

How does the two-project model work in practice?#

In the product project, you map CHANNEL and ITEM representing individual items. In the specification project, you keep the same CHANNEL but choose the wrapping element of supplementary information as ITEM. Both projects load the same input feed, and Blending Bull then combines them into a single output.

Why is Blending Bull essential for merging complex structures?#

Mergado itself cannot combine data from two different projects with different objects (products). Blending Bull creates an output file to which you can add both outputs and optionally modify them further using rules. This gives you a complete data structure matching the original feed.

What are “Find and replace” rules in Blending Bull for?#

These rules let you bulk-change element names, root tags, or parts of the header and footer. This is a solution for cases when you need to modify the output feed to match a specific format. This way, you can, for example, rename SHOP to PRODUCTS or other key elements.

Can root elements of the output feed be directly edited in Mergado?#

No, root elements cannot be directly edited in the standard interface. They can be influenced either by creating a Custom Format based on a sample feed, or through edits in Blending Bull. Both approaches ensure the correct output structure.

When does it make sense to create a custom template using an output Custom Format?#

If you have a clearly defined output XML structure, for example, a partner specification or your own system, an output Custom Format is the cleanest solution. By defining the format from a sample feed, you ensure Mergado always generates data in the required form. This approach is the most stable for long-term use.

Is it possible to request adding a new official format to Mergado?#

Yes, if you have documentation and a clear specification of the target format, you can ask support to add it among official integrations. This process is subject to prioritization and may take longer. If you need results quickly, an output Custom Format or Blending Bull is a faster path.

How do I know the two-project model is needed?#

If information that is located outside ITEM is missing after import, or if the feed contains multiple levels above products, the two-project model is usually the only way to preserve the complete structure. It is also needed when you need to combine product data with global information stored outside the items themselves.

8. Terminology Explained#

Mergado XML as a Universal Language#

Mergado XML works as a universal intermediate format through which Mergado converts all product data. There is no need for a separate converter for each input and output format pair – one shared structure into which data is translated is sufficient.

Custom Format as a Dictionary and Grammar Rules#

Custom Format determines how individual elements of your feed “translate” into Mergado XML. It is a set of rules that lets Mergado recognize the structure of virtually any feed.

Sample Feed as the Target Language#

When creating an output format, the sample feed serves as the definition of what the resulting structure should look like. Mergado loads from it:

• the root structure,
• element names,
• item organization.

This gives you an output feed precisely matching your own specification.

Conversion Examples#

• Import (supplier feed –> online store format)
  • Mergado prepares the structure to be compatible with the online store format, including prices, availability, or parameters.
• Export (internal data –> Heureka, Google, custom platforms)
  • If the platform does not offer a direct export, Custom Format lets you create an output that meets the required specification.