🚧 [#4019] Handle special case for files

The variable for file components has type 'array', but if only one file can be uploaded we want to be able to map it to attributes of type 'string' in the JSON schema. If multiple files can be uploaded, then we map it to 'array' attributes

src/openforms/js/components/admin/form_design/registrations/objectsapi/ObjectsApiVariableConfigurationEditor.js

@@ -5,7 +5,7 @@ import React, {useContext} from 'react';
 import {FormattedMessage} from 'react-intl';
 import {useAsync, useToggle} from 'react-use';
 
-import {APIContext} from 'components/admin/form_design/Context';
+import {APIContext, FormContext} from 'components/admin/form_design/Context';
 import {REGISTRATION_OBJECTS_TARGET_PATHS} from 'components/admin/form_design/constants';
 import Field from 'components/admin/forms/Field';
 import Fieldset from 'components/admin/forms/Fieldset';
@@ -34,7 +34,7 @@ import {asJsonSchema} from './utils';
  */
 const ObjectsApiVariableConfigurationEditor = ({variable}) => {
   const {csrftoken} = useContext(APIContext);
-
+  const {components} = useContext(FormContext);
   const [jsonSchemaVisible, toggleJsonSchemaVisible] = useToggle(false);
   const {values: backendOptions, getFieldProps, setFieldValue} = useFormikContext();
 
@@ -73,7 +73,7 @@ const ObjectsApiVariableConfigurationEditor = ({variable}) => {
       const response = await post(REGISTRATION_OBJECTS_TARGET_PATHS, csrftoken, {
         objecttypeUrl: objecttype,
         objecttypeVersion,
-        variableJsonSchema: asJsonSchema(variable),
+        variableJsonSchema: asJsonSchema(variable, components),
       });
 
       return response.data;

src/openforms/js/components/admin/form_design/registrations/objectsapi/utils.js

@@ -48,9 +48,20 @@ const FORMAT_TYPE_MAP = {
 /**
  * Return a JSON Schema definition matching the provided variable.
  * @param {Object} variable - The current variable
+ * @param {Object} components - The components available in the form. The key is the component key, the value is the
+ * component definition.
  * @returns {Object} - The JSON Schema
  */
-const asJsonSchema = variable => {
+const asJsonSchema = (variable, components) => {
+  // Figure out if the component is a file component (special case)
+  const componentDefinition = components[variable.key];
+  if (componentDefinition && componentDefinition.type === 'file') {
+    // If it is, and it has multiple == True, then type is array
+    if (componentDefinition.multiple) return {type: 'array'};
+    // Otherwise it's string (URL of the document)
+    return {type: 'string', format: 'uri'};
+  }
+
   if (VARIABLE_TYPE_MAP.hasOwnProperty(variable.dataType))
     return {type: VARIABLE_TYPE_MAP[variable.dataType]};
   return {