Fix for string form fields (#10814)

* Fix for string form fields

- replace null values with empty strings

* Expose more serializer metadata

* Check if null values are not allowed

* Fix type

* Try removing feature

* Reduce deltas

* Remove extra field attrs entirely (for testing)

* Comment out changes

* Tweak form values

* Fix for form validation

src/backend/InvenTree/InvenTree/metadata.py

@@ -420,6 +420,13 @@ class InvenTreeMetadata(SimpleMetadata):
         if field_info['type'] == 'dependent field':
             field_info['depends_on'] = field.depends_on
 
+        # Extends with extra attributes from the serializer
+        extra_field_attributes = ['allow_blank', 'allow_null']
+
+        for attr in extra_field_attributes:
+            if hasattr(field, attr):
+                field_info[attr] = getattr(field, attr)
+
         # Extend field info if the field has a get_field_info method
         if (
             not field_info.get('read_only')

src/frontend/lib/types/Forms.tsx

@@ -48,6 +48,8 @@ export type ApiFormFieldHeader = {
  * @param model : The model to use for related fields
  * @param filters : Optional API filters to apply to related fields
  * @param required : Whether the field is required
+ * @param allow_null: Whether the field allows null values
+ * @param allow_blank: Whether the field allows blank values
  * @param hidden : Whether the field is hidden
  * @param disabled : Whether the field is disabled
  * @param error : Optional error message to display
@@ -103,6 +105,8 @@ export type ApiFormFieldType = {
   choices?: ApiFormFieldChoice[];
   hidden?: boolean;
   disabled?: boolean;
+  allow_null?: boolean;
+  allow_blank?: boolean;
   exclude?: boolean;
   read_only?: boolean;
   placeholder?: string;

src/frontend/src/components/forms/ApiForm.tsx

@@ -24,7 +24,11 @@ import { type NavigateFunction, useNavigate } from 'react-router-dom';
 
 import { isTrue } from '@lib/functions/Conversion';
 import { getDetailUrl } from '@lib/functions/Navigation';
-import type { ApiFormFieldSet, ApiFormProps } from '@lib/types/Forms';
+import type {
+  ApiFormFieldSet,
+  ApiFormFieldType,
+  ApiFormProps
+} from '@lib/types/Forms';
 import { useApi } from '../../contexts/ApiContext';
 import {
   type NestedDict,
@@ -375,16 +379,29 @@ export function ApiForm({
 
     Object.keys(data).forEach((key: string) => {
       let value: any = data[key];
-      const field_type = fields[key]?.field_type;
-      const exclude = fields[key]?.exclude;
+      const field: ApiFormFieldType = fields[key] ?? {};
+      const field_type = field?.field_type;
+      const exclude = field?.exclude;
 
       if (field_type == 'file upload' && !!value) {
         hasFiles = true;
       }
 
-      // Ensure any boolean values are actually boolean
-      if (field_type === 'boolean') {
-        value = isTrue(value) || false;
+      // Special consideration for various field types
+      switch (field_type) {
+        case 'boolean':
+          // Ensure boolean values are actually boolean
+          value = isTrue(value) || false;
+          break;
+        case 'string':
+          // Replace null string values with an empty string
+          if (value === null && field?.allow_null == false) {
+            value = '';
+            jsonData[key] = value;
+          }
+          break;
+        default:
+          break;
       }
 
       // Stringify any JSON objects
@@ -393,7 +410,9 @@ export function ApiForm({
           case 'file upload':
             break;
           default:
-            value = JSON.stringify(value);
+            if (value !== null && value !== undefined) {
+              value = JSON.stringify(value);
+            }
             break;
         }
       }