Fix passing redoc UI parameters

Currently passing redoc UI parameters has the following issues:
* It puts json-ed values of parameters in single quotes, which will
  break if the value itself contains single quotes.
* If the value is falsy, only the name of the parameter is used. This
  syntax is *not* treated as falsy by redoc.

The latter cases the download button to be always hidden, because the
default parameters have "hide-download-button": False. There is no way
to un-hide it with the current code.

Change this to use the javascript API to pass parameters[1], which is
much simpler and more robust.

Also, stop using the "next" version of redoc, as suggested here[2]. This
was an old release candidate for version 2. Use the officially released
version 2.

[1] https://redocly.com/docs/redoc/deployment/html/#the-redoc-object
[2] fastapi/fastapi#9700

src/openapipages/redoc.py

@@ -19,7 +19,7 @@
     "theme": {
         "typography": {"code": {"wrap": True}},
     },
-    "hide-download-button": False,
+    "hideDownloadButton": False,
 }
 
 
@@ -35,7 +35,7 @@ class ReDoc(Base):
             It is normally set to a CDN URL.
             """
         ),
-    ] = "https://cdn.jsdelivr.net/npm/redoc@next/bundles/redoc.standalone.js"
+    ] = "https://cdn.jsdelivr.net/npm/redoc@2/bundles/redoc.standalone.js"
     with_google_fonts: Annotated[
         bool,
         Doc(
@@ -64,15 +64,6 @@ def render(self) -> str:
         current_redoc_ui_parameters = default_parameters.copy()
         current_redoc_ui_parameters.update(self.ui_parameters or {})
 
-        def add_redoc_ui_parameters() -> str:
-            _props = ""
-            for key, value in current_redoc_ui_parameters.items():
-                if value:
-                    _props += f"{key}='{json.dumps(value)}' "
-                else:
-                    _props += f"{key} "
-            return _props
-
         html_template = self.get_html_template()
         return html_template.format(
             title=self.title,
@@ -82,7 +73,7 @@ def add_redoc_ui_parameters() -> str:
             head_js_str=self.get_head_js_str(),
             tail_js_str=self.get_tail_js_str(),
             google_fonts_str=google_fonts_str,
-            redoc_ui_parameters=add_redoc_ui_parameters(),
+            redoc_ui_parameters=json.dumps(current_redoc_ui_parameters, indent=2),
         )
 
     def get_html_template(self) -> str:
@@ -109,8 +100,15 @@ def get_html_template(self) -> str:
                 <noscript>
                     ReDoc requires Javascript to function. Please enable it to browse the documentation.
                 </noscript>
-                <redoc spec-url="{openapi_url}" {redoc_ui_parameters}></redoc>
+                <div id="redoc-container"></div>
                 {tail_js_str}
+                <script>
+                  Redoc.init(
+                    "{openapi_url}",
+                    {redoc_ui_parameters},
+                    document.getElementById("redoc-container")
+                  )
+                </script>
             </body>
         </html>
         """

tests/test_redoc.py

@@ -10,7 +10,8 @@ def test_redoc_plain() -> None:
     response = client.get("/redoc-plain")
     assert response.status_code == 200, response.text
     assert response.headers["content-type"] == "text/html; charset=utf-8"
-    assert "redoc@next" in response.text
+    assert "redoc@2" in response.text
+    assert '"hideDownloadButton": false' in response.text
 
 
 def test_redoc_custom() -> None: