feat(numericalInput): endpoint added to validate a numerical input (#37677)

To be used in the visual Problem editor to validate numeric input. 

Part of: https://github.com/openedx/frontend-app-authoring/issues/1680

cms/djangoapps/contentstore/rest_api/v2/serializers/utils.py

@@ -0,0 +1,17 @@
+"""
+Serializers for the contentstore v2 utils views module.
+
+This module contains DRF serializers for different utils like validations.
+"""
+
+from rest_framework import serializers
+
+
+class NumericalInputValidationRequestSerializer(serializers.Serializer):
+    formula = serializers.CharField()
+
+
+class NumericalInputValidationReponseSerializer(serializers.Serializer):
+    preview = serializers.CharField()
+    is_valid = serializers.BooleanField()
+    error = serializers.CharField(allow_null=True)

cms/djangoapps/contentstore/rest_api/v2/urls.py

@@ -3,7 +3,7 @@
 from django.conf import settings
 from django.urls import path, re_path
 
-from cms.djangoapps.contentstore.rest_api.v2.views import downstreams, home
+from cms.djangoapps.contentstore.rest_api.v2.views import downstreams, home, utils
 
 app_name = "v2"
 
@@ -33,4 +33,8 @@ urlpatterns = [
         downstreams.SyncFromUpstreamView.as_view(),
         name="sync_from_upstream"
     ),
+    re_path(
+        '^validate/numerical-input/$',
+        utils.NumericalInputValidationView.as_view(),
+        name='numerical_input_validation'),
 ]

cms/djangoapps/contentstore/rest_api/v2/views/utils.py

@@ -0,0 +1,22 @@
+"""
+Common utilities for V2 APIs.
+"""
+from rest_framework.response import Response
+from rest_framework.generics import GenericAPIView
+from rest_framework import permissions
+from cms.djangoapps.contentstore.rest_api.v2.serializers.utils import NumericalInputValidationRequestSerializer
+from xmodule.capa.inputtypes import preview_numeric_input
+
+
+class NumericalInputValidationView(GenericAPIView):
+    """Class in charge of NumericalInputValidations"""
+    permission_classes = (permissions.IsAuthenticated,)
+    serializer_class = NumericalInputValidationRequestSerializer
+
+    def post(self, request):
+        """function to validate a math expression (formula) and return of the numeric input is valid or not"""
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        formula = serializer.validated_data['formula']
+        result = preview_numeric_input(formula)
+        return Response(result, status=200)

xmodule/capa/inputtypes.py

@@ -49,9 +49,9 @@ from datetime import datetime
 
 import html5lib
 import nh3
-import pyparsing
 import six
 from calc.preview import latex_preview
+import pyparsing
 from chem import chemcalc
 from lxml import etree
 
@@ -1300,22 +1300,47 @@ class FormulaEquationInput(InputTypeBase):
 
         result["request_start"] = int(get.get("request_start", 0))
 
+        # TODO add references to valid variables and functions
+        # At some point, we might want to mark invalid variables as red
+        # or something, and this is where we would need to pass those in.
         try:
-            # TODO add references to valid variables and functions
-            # At some point, we might want to mark invalid variables as red
-            # or something, and this is where we would need to pass those in.
-            result["preview"] = latex_preview(formula)
+            numeric_result = preview_numeric_input(formula)
+            # Map results into the correct format
+            result["preview"] = numeric_result["preview"]
+            if numeric_result["error"]:
+                result["error"] = numeric_result["error"]
+            # if formula is invalid return formula
+            if not numeric_result["is_valid"]:
+                result["formula"] = formula
         except pyparsing.ParseException:
-            result["error"] = _("Sorry, couldn't parse formula")
-            result["formula"] = formula
+            result['error'] = _("Sorry, couldn't parse formula")
+            result['formula'] = formula
         except Exception:  # lint-amnesty, pylint: disable=broad-except
-            # this is unexpected, so log
             log.warning("Error while previewing formula", exc_info=True)
             result["error"] = _("Error while rendering preview")
+            return result
 
         return result
 
 
+def preview_numeric_input(formula):
+    """
+    Handles numeric validations, validates that the formula provided is a valid formula.
+    """
+    result = {'preview': '', 'is_valid': True, 'error': ''}
+    try:
+        result['preview'] = latex_preview(formula)
+    except pyparsing.ParseException:
+        result["error"] = "Sorry, couldn't parse formula"
+        result['is_valid'] = False
+        return result
+    except Exception:  # pylint: disable=broad-exception-caught
+        log.warning("Error while previewing formula", exc_info=True)
+        result['error'] = "Error while rendering preview"
+        result['is_valid'] = False
+    return result
+
+
 # -----------------------------------------------------------------------------
 
 

xmodule/capa/tests/test_inputtypes.py

@@ -1361,7 +1361,7 @@ class FormulaEquationTest(unittest.TestCase):
         With parse errors, FormulaEquationInput should give an error message
         """
         # Simulate answering a problem that raises the exception
-        with patch("xmodule.capa.inputtypes.latex_preview") as mock_preview:
+        with patch('xmodule.capa.inputtypes.preview_numeric_input') as mock_preview:
             mock_preview.side_effect = ParseException("Oopsie")
             response = self.the_input.handle_ajax(
                 "preview_formcalc",
@@ -1379,7 +1379,7 @@ class FormulaEquationTest(unittest.TestCase):
         """
         With other errors, test that FormulaEquationInput also logs it
         """
-        with patch("xmodule.capa.inputtypes.latex_preview") as mock_preview:
+        with patch('xmodule.capa.inputtypes.preview_numeric_input') as mock_preview:
             mock_preview.side_effect = Exception()
             response = self.the_input.handle_ajax(
                 "preview_formcalc",