Max length validation

src/wagtail_ai/forms.py

@@ -46,7 +46,7 @@ def clean_prompt(self):
 
 class DescribeImageApiForm(ApiForm):
     image_id = forms.CharField()
-    maxlength = forms.IntegerField(required=False)
+    maxlength = forms.IntegerField(required=False, min_value=0, max_value=4096)
 
 
 class DescribeImageForm(BaseImageForm):

src/wagtail_ai/static_src/image_description/main.tsx

@@ -5,7 +5,7 @@ import wandIcon from '../wand_icon.svg';
 
 document.addEventListener('wagtail-ai:image-form', (event) => {
   const input = event.target as HTMLInputElement;
-  const imageId = input.dataset['wagtailaiImageId'];
+  const imageId = input.dataset.wagtailaiImageId;
   if (!imageId) {
     throw new Error('The attribute data-wagtailai-image-id is missing.');
   }
@@ -27,7 +27,7 @@ document.addEventListener('wagtail-ai:image-form', (event) => {
 
   const button = document.createElement('button');
   button.type = 'button';
-  button.title = input.dataset['wagtailaiButtonTitle'] || '';
+  button.title = input.dataset.wagtailaiButtonTitle || '';
   button.classList.add('button', 'wagtailai-button');
   button.innerHTML = wandIcon;
   flexWrapper.appendChild(button);

tests/views/test_describe_image.py

@@ -1,3 +1,4 @@
+from http import HTTPStatus
 from typing import cast
 from unittest.mock import ANY, Mock, call
 
@@ -133,3 +134,45 @@ def test_custom_rendition_filter(admin_client, settings):
     assert response.json() == {
         "message": "This is an echo backend: images/example.max-100x100.jpg"
     }
+
+
+@pytest.mark.parametrize(
+    "maxlength,expected_status,error_message",
+    [
+        (100, HTTPStatus.OK, None),
+        (
+            -1,
+            HTTPStatus.BAD_REQUEST,
+            "Ensure this value is greater than or equal to 0.",
+        ),
+        (
+            10000,
+            HTTPStatus.BAD_REQUEST,
+            "Ensure this value is less than or equal to 4096.",
+        ),
+    ],
+)
+def test_maxlength_validation(
+    admin_client, settings, maxlength, expected_status, error_message
+):
+    settings.WAGTAIL_AI = {
+        "BACKENDS": {
+            "echo": {
+                "CLASS": "wagtail_ai.ai.echo.EchoBackend",
+                "CONFIG": {
+                    "MODEL_ID": "echo",
+                    "TOKEN_LIMIT": 123123,
+                },
+            },
+        },
+        "IMAGE_DESCRIPTION_BACKEND": "echo",
+    }
+
+    image = cast(Image, ImageFactory())
+    response = admin_client.post(
+        reverse("wagtail_ai:describe_image"),
+        data={"image_id": image.pk, "maxlength": maxlength},
+    )
+    assert response.status_code == expected_status
+    if error_message is not None:
+        assert response.json() == {"error": error_message}