Add the chooser-url as a url path.

wagtail_draftail_snippet/urls.py

@@ -1,11 +1,25 @@
+from django.urls import path
 from django.conf.urls import url
 
+from wagtail.snippets.views import chooser
+
 from .views import choose_snippet_link_model, choose_snippet_embed_model
 
 
 app_name = "wagtaildraftailsnippet"
 
 urlpatterns = [
-    url(r"^choose-link-model/$", choose_snippet_link_model, name="choose-snippet-link-model"),
-    url(r"^choose-embed-model/$", choose_snippet_embed_model, name="choose-snippet-embed-model"),
+    url(
+        r"^choose-link-model/$",
+        choose_snippet_link_model,
+        name="choose-snippet-link-model",
+    ),
+    url(
+        r"^choose-embed-model/$",
+        choose_snippet_embed_model,
+        name="choose-snippet-embed-model",
+    ),
+    path(
+        "choose/", chooser.ChooseView.as_view(), name="choose_generic"
+    ),  # This exists only to get the additional URL params added via JS in wagtail-draftail-snippet.js line 50
 ]

wagtail_draftail_snippet/wagtail_hooks.py

@@ -8,8 +8,10 @@ from wagtail.core import hooks
 
 from . import urls
 from .richtext import (
-    ContentstateSnippetLinkConversionRule, ContentstateSnippetEmbedConversionRule,
-    SnippetLinkHandler, SnippetEmbedHandler,
+    ContentstateSnippetLinkConversionRule,
+    ContentstateSnippetEmbedConversionRule,
+    SnippetLinkHandler,
+    SnippetEmbedHandler,
 )
 
 
@@ -65,18 +67,16 @@ def register_snippet_embed_feature(features):
 
 @hooks.register("insert_editor_js")
 def editor_js():
-    return format_html(
-        """
+
+    html = f"""
             <script>
-                window.chooserUrls.snippetChooser = '{0}';
-                window.chooserUrls.snippetLinkModelChooser = '{1}';
-                window.chooserUrls.snippetEmbedModelChooser = '{2}';
-            </script>
-        """,
-        reverse('wagtailsnippets:choose_generic'),
-        reverse("wagtaildraftailsnippet:choose-snippet-link-model"),
-        reverse("wagtaildraftailsnippet:choose-snippet-embed-model"),
-    )
+                window.chooserUrls.snippetChooser = '{reverse('wagtaildraftailsnippet:choose_generic')}';
+                window.chooserUrls.snippetLinkModelChooser = '{reverse("wagtaildraftailsnippet:choose-snippet-link-model")}';
+                window.chooserUrls.snippetEmbedModelChooser = '{reverse("wagtaildraftailsnippet:choose-snippet-embed-model")}';
+            </script>    
+            """
+
+    return format_html(html)
 
 
 @hooks.register("register_admin_urls")