Volto: Return additional fields for listing views

1

I'm now working on a custom listing view. I'm trying to figure out the pattern for providing additional fields to listing items.
Out of the box, Volto retrieves listings that return @id, @type, description, title and url
Like this:

{
 @id: "http://localhost:3000/myfolder",
@type: "folder",
description: "This is my folder",
review_state: "open",
title: "My folder",
url: "/myfolder",
}

I'd like to also return the tags associated with each listing item.
So something like this:

{
 @id: "http://localhost:3000/myfolder",
@type: "folder",
description: "This is my folder",
review_state: "open",
title: "My folder",
url: "/myfolder",
tags: ["interesting","stimulating","last one"]
}
2

I don't know if this is the best approach, but I know it can work.
This example: 26. Volto View Components: A Listing View for Talks – Mastering Plone 6 Development — Plone Training 2021 documentation ... showcases the use of Volto's searchContent helper.

I feel there's a nicer way* to do this but this way is documented and I know it will work.
The searchContent helper provides a way to send a custom query to the api. More important is the ability to request the fullobjects when doing the query, so I'll get my tags.

*I could be wrong about the nicer way.

React.useEffect(() => {
    dispatch(
      searchContent(
        '/',
        {
          portal_type: ['talk'],
          fullobjects: true,
        },
        'conferencetalks',
      ),
    );
  }, [dispatch]);
3

There's a nice new utlity that @ericof introduced in plone.volto, you need to register a utility and it can provide a list of portal catalog column names, see how the image_field is handled here: plone.volto/configure.zcml at main · plone/plone.volto · GitHub and plone.volto/summary.py at main · plone/plone.volto · GitHub

1 Like
4

Thanks @tiberiuichim so either (1) use the searchContent helper or (2) solve it on the backend with the 'JSONSummarySerializerMetadata'. If we're playing to the skills of a frontend developer then (1) is the better option.

5

Avoiding full_objects is better, though. Reducing the problem, we're basically talking about "waking zodb objects for listing vs just reading their metadata from the catalog", but it goes even further: content serialization can get quite large (it includes the blocks, information about children, etc) and that type of info gets repeated across all the items in the listing.

6

Agreed, but may be out of the reach of a frontend dev (at least with the available patterns).

7

Yes, indeed, it's not in the reach of frontend developers (although I have a colleague who started as a frontend dev exclusively with React and now he's all over, poking through the backend stack).

On the other hand, outside Volto, we didn't really have a "frontend stack only" developer role with Plone.

"frontend only" solution would require this: Listing variation templates should be able to control retrieved fields · Issue #2714 · plone/volto · GitHub and the plone.restapi counterpart. But we need a champion for this.

1 Like
8

@tiberiuichim Is it possible to simply overwrite the summary.py and thus expand the list of fields in JSONSummarySerializerMetadata? I found a dark hint that you should create an overrides folder in your addon and save a summary.py with changed content there, but unfortunately this has no effect

9

OK, I have already found the solution.
I just have to register the utility in the context of my addon then it also works with the changed summary.py

10

Hmm, I have now activated a RichText field as a behavior in the content-type News Item. This field is simply called "text" . If I try to enter this field in default_metadata_fields of the JSONSummarySerializerMetadata class in order to be able to see the field in the listing (summary), the following error occurs

 test-backend-1  |   Module plone.restapi.serializer.converters, line 80, in default_converter 
 test-backend-1  | TypeError: No converter for making RichTextValue object. (Did you mean <attribute>.raw or <attribute>.output?) (<class 'plone.app.textfield.value.RichTextValue'>) JSON compatible.

If I now set a field_accessors for text based on the example from summary.py, the error in the listing is gone.

def field_accessors(self):
        return {
            ...
            "text": "Text",
        }

I then also see the "text" field in the listing in the React Developer Tools... but it is zero instead of the entered test string.

How can I correctly call the converter for rich text in the serializer?

11

Your code probably goes through this line:

It means there's no default simple adaptor for RichTextValue. The existing one is a multi-adaptor:

You need to register a simple adaptor for RichTextValue, similar to: