✨ [#4980] Add function to generate JSON schema from a form and list o…

…f variables to include

Also updated the JSON dump plugin

src/openforms/forms/utils.py

@@ -3,7 +3,7 @@
 import random
 import string
 import zipfile
-from typing import Any
+from typing import Any, Sequence
 from uuid import uuid4
 
 from django.conf import settings
@@ -16,9 +16,13 @@
 from rest_framework.test import APIRequestFactory
 
 from openforms.formio.migration_converters import CONVERTERS, DEFINITION_CONVERTERS
+from openforms.formio.registry import register as component_registry
 from openforms.formio.utils import iter_components
 from openforms.typing import JSONObject
 from openforms.variables.constants import FormVariableSources
+from openforms.variables.registry import (
+    register_static_variable as static_variable_registry,
+)
 
 from .api.datastructures import FormVariableWrapper
 from .api.serializers import (
@@ -129,6 +133,72 @@ def form_to_json(form_id: int) -> dict:
     return resources
 
 
+# TODO-4980: what should the name be? Do we need the submission, or is just the form
+#  sufficient here?
+# TODO-4980: pass form_id instead of the form?
+def form_variables_to_json_schema(
+    form: Form, variables_to_include: Sequence[str]
+) -> JSONObject:
+    """Generate a JSON schema from a form, for the specified variables.
+
+    :param form: The form to generate JSON schema for.
+    :param variables_to_include: Variables that will be included in the schema.
+
+    :returns: A JSON schema representing the form variables.
+    """
+
+    # Handle static variables
+    static_var_properties = {
+        key: static_variable_registry[key].as_json_schema()
+        for key in variables_to_include
+        if key in static_variable_registry
+    }
+
+    # Handle form variables
+    all_form_vars = {var.key: var for var in form.formvariable_set.all()}
+
+    # TODO-4980: add to FormVariable?
+    def get_json_schema_from_form_variable(form_variable):
+        form_def = form_variable.form_definition
+
+        component = form_def.configuration_wrapper.component_map[form_variable.key]
+        component_plugin = component_registry[component["type"]]
+
+        return component_plugin.as_json_schema(component)
+
+    form_var_properties = {
+        key: get_json_schema_from_form_variable(all_form_vars[key])
+        for key in variables_to_include
+        if key in all_form_vars
+    }
+
+    # Required
+    def is_required(form_variable):
+        form_def = form_variable.form_definition
+        component = form_def.configuration_wrapper.component_map[form_variable.key]
+
+        validate = component.get("validate", {})
+        return validate.get("required", False)
+
+    required_form_variables = [
+        var for var in form_var_properties.keys() if is_required(all_form_vars[var])
+    ]
+
+    required = [*static_var_properties.keys(), *required_form_variables]
+
+    # Result
+    var_properties = {**static_var_properties, **form_var_properties}
+    schema = {
+        "$schema": "https://json-schema.org/draft/2020-12/schema",
+        "type": "object",
+        "properties": var_properties,
+        "required": required,
+        "additionalProperties": False,
+    }
+
+    return schema
+
+
 def export_form(form_id, archive_name=None, response=None):
     resources = form_to_json(form_id)
 

src/openforms/registrations/contrib/json_dump/plugin.py

@@ -8,6 +8,7 @@
 from zgw_consumers.client import build_client
 
 from openforms.formio.typing import Component
+from openforms.forms.utils import form_variables_to_json_schema
 from openforms.submissions.models import (
     Submission,
     SubmissionFileAttachment,
@@ -32,6 +33,7 @@ def register_submission(
     ) -> dict:
         state = submission.load_submission_value_variables_state()
 
+        # Generate values
         all_values: JSONObject = {
             **state.get_static_data(),
             **state.get_data(),  # dynamic values from user input
@@ -42,23 +44,11 @@ def register_submission(
             if key in options["variables"]
         }
 
-        # Process attachments
-        self.process_variables(submission, values)
-
         # Generate schema
-        # TODO: will be added in #4980. Hardcoded example for now.
-        schema = {
-            "$schema": "https://json-schema.org/draft/2020-12/schema",
-            "type": "object",
-            "properties": {
-                "static_var_1": {"type": "string", "pattern": "^cool_pattern$"},
-                "form_var_1": {"type": "string"},
-                "form_var_2": {"type": "string"},
-                "attachment": {"type": "string", "contentEncoding": "base64"},
-            },
-            "required": ["static_var_1", "form_var_1", "form_var_2"],
-            "additionalProperties": False,
-        }
+        schema = form_variables_to_json_schema(submission.form, options["variables"])
+
+        # Post-processing
+        self.post_processing(submission, values, schema)
 
         # Send to the service
         data = json.dumps({"values": values, "schema": schema}, cls=DjangoJSONEncoder)
@@ -77,11 +67,17 @@ def check_config(self) -> None:
         pass
 
     @staticmethod
-    def process_variables(submission: Submission, values: JSONObject):
-        """Process variables.
+    def post_processing(
+        submission: Submission, values: JSONObject, schema: JSONObject
+    ) -> None:
+        """Post-processing of values and schema.
 
         File components need special treatment, as we send the content of the file
         encoded with base64, instead of the output from the serializer.
+
+        :param submission: Submission
+        :param values: JSONObject
+        :param schema: JSONObject
         """
         state = submission.load_submission_value_variables_state()
 
@@ -97,6 +93,7 @@ def process_variables(submission: Submission, values: JSONObject):
 
             component = get_component(variable)
             if component is None or component["type"] != "file":
+                # Only file components need to be processed
                 continue
 
             encoded_attachments: list[JSONValue] = [
@@ -136,11 +133,11 @@ def encode_attachment(attachment: SubmissionFileAttachment) -> str:
         return base64.b64encode(f.read()).decode()
 
 
-def get_component(variable: SubmissionValueVariable) -> Component:
+def get_component(variable: SubmissionValueVariable) -> Component | None:
     """Get the component from a submission value variable.
 
     :param variable: SubmissionValueVariable
-    :return component: Component
+    :return component: None if the form variable has no form definition
     """
     config_wrapper = variable.form_variable.form_definition.configuration_wrapper
     component = config_wrapper.component_map[variable.key]