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Version: 13.x (Current)

Form Service Backend

The Form Service Backend is a Mia-Platform plugin that acts as a BFF (Backend For Frontend) for the Form Service Frontend.

How it works

The Form Service Backend works with the Form Service Frontend that provides the Form Builder and Form Visualizer UI. Further information about the frontend routes are available here.

The backend service exposes the following APIs:

Form Builder

  • GET /builder/config: it returns the configuration needed to show the Form Builder visualizer;
  • POST /builder/schemas: it allows saving the created form;
  • GET /builder/schemas/{id}: it returns one form by ID;
  • PUT /builder/schemas/{id}: it updates one form by ID.

Form Visualizer

  • GET /visualizer/config: it returns the configuration needed by the form visualizer;
  • GET /visualizer/schemas/{id}: it returns a configured form that will be shown in the Form Visualizer;
  • POST /visualizer/forms: it saves the submitted data of a user that filled a form shown in the Form Visualizer;
  • GET /visualizer/forms/{id}: it returns a submitted form by ID, enabling the review of data provided by the end user;
  • PUT /visualizer/forms/{id}: it updates a submitted form by ID;
  • GET /visualizer/assignments/{assignmentId}/schema-id: (from version 1.2.0) it returns a form ID given a form assignment ID;
  • DELETE /visualizer/forms/{id}: it deletes a submitted form by ID and its draft;
  • POST /visualizer/forms/draft/{formId}: if formId is undefined it saves a form and its draft, otherwise it saves the draft of the form;
  • GET /visualizer/forms/export (version 1.7.0 or later required): it returns a CSV containing the forms data based on a given schema and created in a given period;

These endpoints are defined in the Form Service Backend and are called by the Form Service Frontend plugin (regardless being integrated in micro-lc or Headless CMS). Discover more about the frontend integration here.

Form data versioning support

From version 1.4.0 the Form-Service Backend supports the versioning of the form data, by including the parameter _v to the request performed to retrieve form data. The _v parameter specifies the version of the form data to be retrieved. If the ENABLE_VERSIONING environment variable is set to true, the _v parameter is forwarded to the service in charge of retrieving the form data.


Let us suppose that the submit_url has been set to http://microservice/resource. When the Form-Service Frontend triggers a request GET /visualizer/forms/{id}?_v=1 to the Form-Service Backend with a non-null _v parameter, the Form-Service Backend will trigger a request GET http://microservice/resource/{id}?_v=1

In order to obtain form data versioning, the calls to the Form-Service Frontend must be done including the _v parameter. See here for Form-Service Frontend usage.

Form draft support

From version 1.5.0 the Form-Service Backend allows to retrieve draft data by including the parameter _status to the request performed to retrieve the form. If the _status parameter is equal to draft the data retrieved in the request GET /visualizer/forms/{id}?_status=draft is the draft, otherwise it retrives the stable form data.

Every form has two parameters: isValid and hasDraft. The first one indicates if the form has been submitted. The latter indicates if the draft of the form exists.

Form data CSV export

From version 1.7.0 the Form-Service Backend allows to export form data in CSV format, by calling the GET /visualizer/forms/export endpoint.

This endpoint accepts the following query parameters:

  • startDate (required): filter the forms created after the given date/time;
  • endDate (required): filter the forms created before the given date/time;
  • formSchemaId (required): filter the forms with the given schema;
  • compatibleWithExcel (optional, default: false): returns a CSV compatible with Excel (accepted values: true or false).

When opening regular CSV files with Excel, the content is parsed according to certain client localization settings, which may cause parsing issues. To ensure compatibility with Excel, we need to export a CSV crafted for Excel, which is not suitable to be opened with other tools. For this reason, since version 1.7.1 we provide an additional query parameter - compatibleWithExcel - you can use to get a CSV fully compatible with Excel.

This endpoint flatten all the form fields, using the dot character as separator, and returns a CSV where each column corresponds to a flattened JSON field. So, if we have a form looking like this:

"_id": "6246b2aff30214fb40d3e86d",
"formSchemaId": "62162180544cea83e8e130e7",
"data": {
"name": "Mario",
"surname": "Rossi",

the resulting columns in the CSV would be, in the exact order, _id, formSchemaId, and data.surname:


If there is no form data matching the given filters, an empty CSV with headers is returned. For instance:


This endpoint builds the list of CSV columns from the form schema and does not support all field types.

We provide limited support for the following field types:

  • datagrid: the value is an array, which is not flattened, so a single field is returned;
  • editgrid: the value is an array, which is not flattened, so a single field is returned.

We do not support the following field types, which means that fields with any of these type will not be included in the CSV:

  • all premium fields;
  • address: the value is an arbitrary object, depending on the external service providing geolocation info;
  • htmlelement: this field is used to display content on the form, it does not have an associated value;
  • content: this field is used to display content on the form, it does not have an associated value;
  • datamap: the value is an object with arbitrary properties, depending on user input;
  • tree: the value is an arbitrary object.

You can configure the Form Service Backend to:

  • perform lookups on certain fields and replacing an existing value - for example a user or form schema IDs - with a more human-readable value (if, for any reason, a lookup on a form field fails, the service ignores the error and simply leaves the existing value unmodified);
  • configure some redirects, in particular when the GET /export endpoint and the submit URL targets different services and you want the Form Service, every time it encounters a submit URL as lookup data source, to automatically call a different endpoint to fetch lookup data, always appending /export);
  • add some specific fields as columns at the beginning of the CSV before the fields derived from the form schema (if the forms are stored in a CRUD collection, you may want to include its predefined properties).

Please take a look at the Configuration section to understand how to configure fields, lookups and redirects.

Further details

Follow the pages below to know more about the Form Service Backend:


The Form Service Backend does not perform form validation. Validation is only performed in the frontend if the Form Service Frontend plugin is used.

We recommend building you own form validation in a dedicated backend microservice.

This may change in the future.


If a form-schema is modified, the data from filled-out forms is not lost. The API GET /visualizer/forms/:formId returns the completed data in the data field. However, in the formSchema field, components related to the completed data may be missing if they have been modified or deleted. As a result, these fields and their completed data will not be visible in the visualizer.

If a form-schema is deleted, the data from filled-out forms is not lost. However, the API GET /visualizer/forms/:formId will return a 500 Internal Server Error because it cannot retrieve the form-schema of the form.