fix form element names of nested embedded model fields

Author: timgraham

django_mongodb_backend/forms/fields/embedded_model.py

@@ -20,9 +20,17 @@ def decompress(self, value):
 
 
 class EmbeddedModelBoundField(forms.BoundField):
+    def __init__(self, form, field, name, prefix_override=None):
+        super().__init__(form, field, name)
+        # prefix_override overrides the prefix in self.field.form_kwargs so
+        # that nested embedded model form elements have the correct name.
+        self.prefix_override = prefix_override
+
     def __str__(self):
         """Render the model form as the representation for this field."""
         form = self.field.model_form_cls(instance=self.value(), **self.field.form_kwargs)
+        if self.prefix_override:
+            form.prefix = self.prefix_override
         return mark_safe(f"{form.as_div()}")  # noqa: S308
 
 
@@ -53,7 +61,9 @@ def compress(self, data_dict):
         return self.model_form._meta.model(**values)
 
     def get_bound_field(self, form, field_name):
-        return EmbeddedModelBoundField(form, self, field_name)
+        # Nested embedded model form fields need a double prefix.
+        prefix_override = f"{form.prefix}-{self.model_form.prefix}" if form.prefix else None
+        return EmbeddedModelBoundField(form, self, field_name, prefix_override)
 
     def bound_data(self, data, initial):
         if self.disabled:

tests/model_forms_/test_embedded_model.py

@@ -216,3 +216,40 @@ def test_all_missing_data(self):
         form = BookForm(data, instance=book)
         self.assertFalse(form.is_valid())
         self.assertEqual(form.errors["publisher"], ["This field is required."])
+
+    def test_rendering(self):
+        form = BookForm()
+        self.assertHTMLEqual(
+            str(form.fields["publisher"].get_bound_field(form, "publisher")),
+            """
+            <div>
+              <label for="id_publisher-name">Name:</label>
+              <input type="text" name="publisher-name" maxlength="50"
+                required id="id_publisher-name">
+            </div>
+            <div>
+              <fieldset>
+                <legend>Address:</legend>
+                <div>
+                  <label for="id_publisher-address-po_box">PO Box:</label>
+                  <input type="text" name="publisher-address-po_box" maxlength="50"
+                    id="id_publisher-address-po_box">
+                </div>
+                <div>
+                  <label for="id_publisher-address-city">City:</label>
+                  <input type="text" name="publisher-address-city" maxlength="20"
+                    required id="id_publisher-address-city">
+                </div>
+                <div>
+                  <label for="id_publisher-address-state">State:</label>
+                  <input type="text" name="publisher-address-state" maxlength="2"
+                    required id="id_publisher-address-state">
+                </div>
+                <div>
+                  <label for="id_publisher-address-zip_code">Zip code:</label>
+                  <input type="number" name="publisher-address-zip_code"
+                    required id="id_publisher-address-zip_code">
+                </div>
+              </fieldset>
+            </div>""",
+        )