Objects API "contract" feature - release blockers

[sergei-maertens]

Follow up from #3688, these aspects should land in the 2.6 release

• Handling of file fields - a file component (single or multiple uploads) should be possible to explicitly map to a particular (nested) property in the object type definition. Currently all upload fields are processed and result in an array of Documenten API urls, and it's not possible to match which component/file upload matches to which URL. We have the means now to work with structured data, this would be an unfortunate omission.
• Document how one would use a "productaanvraag" user-defined variable and map that into the structure. This facilitates migrating from v1 to v2
• Check if we can replace the payment status PATCH call with a PUT call instead (payment related variables need to be mappable)

[joeribekker]

Refinement: Decided this should be done (and remove the productaanvraag field from the v2 config form)

[Viicos]

For the first checkbox:

• File upload components will be special cased during registration. This part of the code should be adapted:

open-forms/src/openforms/registrations/contrib/objects_api/submission_registration.py

Lines 333 to 350 in c963f22

	dynamic_values = state.get_data()
	static_values = state.static_data()
	static_values.update(
	{
	variable.key: variable.initial_value
	for variable in get_static_variables(
	submission=submission,
	variables_registry=variables_registry,
	)
	}
	)
	variables_values = FormioData(
	{
	**dynamic_values,
	**static_values,
	}
	).data

• Because we only offer compatible target paths to the user (e.g. when configuring the mapping for a textfield component, only the JSON Schema targets of {"type": "string"} will be offered in the UI), we have to special case this compatibility logic:
  • the fileupload component is of datatype array, but when registered, we will deal with the Documents URL (of datatype string). The admin frontend is the one providing a JSON Schema matching a variable, and requests the backend for a list of target paths compatible with such a JSON Schema. So this code will have to be adapted:
    

    open-forms/src/openforms/js/components/admin/form_design/registrations/objectsapi/utils.js

    Lines 49 to 60 in 1bbaeed

    	* Return a JSON Schema definition matching the provided variable.
    	* @param {Object} variable - The current variable
    	* @returns {Object} - The JSON Schema
    	*/
    	const asJsonSchema = variable => {
    	if (VARIABLE_TYPE_MAP.hasOwnProperty(variable.dataType))
    	return {type: VARIABLE_TYPE_MAP[variable.dataType]};
    	return {
    	type: 'string',
    	format: FORMAT_TYPE_MAP[variable.dataType],
    	};
    	};

  • Maybe the variables tab should display datatype: string instead of datatype: array in the datatype column? To make things less confusing