23. Volto View Component: A Default View for a "Talk"¶

In this part we will:

Create a view to display a talk
Register a react view component for content type talk
Write the view component

Topics covered:

View
Displaying data stored in fields of a content type
React Basics

The default visualization for our new content type talk only shows the title, the description and the image.

This paragraph might be rendered in a custom way.

Note

In Plone the default view iterates over all fields in the schema and displays the stored data. In Volto this feature is not implemented yet.

Since we want to show the talk data, we write a custom view for talks.

In the folder frontend you need to add a new file src/components/Views/Talk.jsx. Create the folder Views first.

As a first step, the file will hold only a placeholder.

import React from 'react';

const TalkView = props => {
  return <div>I am the TalkView component!</div>;
};

export default TalkView;

Also add a convenience import of the new component to src/components/index.js:

import TalkView from './Views/Talk';

export { TalkView };

This is is a common practice and allows us to import the new view component as import { TalkView } from './components'; instead of import { TalkView } from './components/Views/Talk';.

Now register the new component as the default view for talks in src/config.js.

import { TalkListView, TalkView } from './components';

// All your imports required for the config here BEFORE this line
import '@plone/volto/config';

export default function applyConfig(config) {
  config.views = {
    ...config.views,
    contentTypesViews: {
      ...config.views.contentTypesViews,
      talk: TalkView,
    },
  };
  return config;
}

This extends the Volto default setting config.views.contentTypesViews with the key/value pair talk: TalkView.
It uses the spread syntax to take the default settings and override what needs to be overrridden.

When Volto is running (with yarn start) it picks up these changes and displays the placeholder in place of the previously used default view.

Now we will improve this view step by step. First we reuse the component DefaultView.jsx in our custom view:

import React from 'react';
import { DefaultView } from '@plone/volto/components';

const TalkView = (props) => {
  return <DefaultView {...props} />;
};
export default TalkView;

We will now add the content from the field details after the DefaultView.

import React from 'react';
import { DefaultView } from '@plone/volto/components';

const TalkView = (props) => {
  const { content } = props;
  return (
    <>
      <DefaultView {...props} />
      <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
    </>
  );
};
export default TalkView;

<> </> is a fragment. The return value of react needs to be one single element.
The variable props is used to receive data from the parent component. As the TalkView component is registered as a content type view, it receives the content data and some more. We will use the content part. So we introduce a constant content to be more explicit.
content.details is the value of the richtext field details with mime type, encoding and the data:
```
{
  'content-type': 'text/html',
  data: '<p>foo bar...</p>',
  encoding: 'utf8'
};
```
See https://plonerestapi.readthedocs.io/en/latest/serialization.html#richtext-fields.
content.details.data holds the raw html. To render it properly we use dangerouslySetInnerHTML (see https://reactjs.org/docs/dom-elements.html#dangerouslysetinnerhtml)

The result is not really beautiful, because the text sticks to the left border of the page. You need to wrap it in a Container to get the same styling as the content of DefaultView:

import React from 'react';
import { DefaultView } from '@plone/volto/components';
import { Container } from 'semantic-ui-react';

const TalkView = props => {
  const { content } = props;
  return (
    <>
      <DefaultView {...props} />
      <Container>
        <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
      </Container>
    </>
  );
};
export default TalkView;

Container is a component from Semantic UI React and needs to be imported before it is used.

We now decide to display the type of talk in the title (E.g. "Keynote: The Future of Plone"). This means we cannot use DefaultView anymore since that displays the title like this: <h1 className="documentFirstHeading">{content.title}</h1>. Instead we display the title and description in a custom way.

This has multiple benefits:

All content can now be wrapped in the same Container which cleans up the html.
We can control where the speaker portrait is displayed. We can now move all information on the speaker into a separate box. The speaker portrait is picked up by the DefaultView because the fields name is image, which is the same as the image from the behavior plone.leadimage.

With this changes we do discard the title tag in the HTML head though. This will change the name occuring in the browser tab or browser head to the current site url. To use the content title instead, you'll have to import the Helmet component, which allows to overwrite all meta tags for the HTML head like the page-title.

import React from 'react';
import { Container } from 'semantic-ui-react';
import { Helmet } from '@plone/volto/helpers';

const TalkView = props => {
  const { content } = props;
  return (
    <Container id="view-wrapper talk-view">
      <Helmet title={content.title} />
      <h1 className="documentFirstHeading">
        <span className="type_of_talk">{content.type_of_talk.title}: </span>
        {content.title}
      </h1>
      {content.description && (
        <p className="documentDescription">{content.description}</p>
      )}
      <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
    </Container>
  );
};
export default TalkView;

content.type_of_talk is the json representation of the value from the choice field type_of_talk: {token: "training", title: "Training"}. We display the title.
The && in {content.description && (<p>...</p>)} makes sure, that this paragraph is only rendered, if the talk actually has a description.

Next we add a block with info on the speaker:

import React from 'react';
import { Container, Header, Segment } from 'semantic-ui-react';

const TalkView = (props) => {
  const { content } = props;
  return (
    <Container id="view-wrapper talk-view">
      <h1 className="documentFirstHeading">
        <span className="type_of_talk">{content.type_of_talk.title} </span>
        {content.title}
      </h1>
      {content.description && (
        <p className="documentDescription">{content.description}</p>
      )}
      <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
      <Segment clearing>
        {content.speaker && <Header dividing>{content.speaker}</Header>}
        <p>{content.company || content.website}</p>
        <a href={`mailto:${content.email}`}>
        {content.email && (
          <p>
            Email: <a href={`mailto:${content.email}`}>{content.email}</a>
          </p>
        )}
        {content.speaker_biography && (
          <div
            dangerouslySetInnerHTML={{
              __html: content.speaker_biography.data,
            }}
          />
        )}
      </Segment>
    </Container>
  );
};
export default TalkView;

We use the component Segment for the box.
{`mailto:${content.email}`} is a template literal

Next we add the image:

import React from 'react';
import { Container, Header, Image, Segment } from 'semantic-ui-react';
import { flattenToAppURL } from '@plone/volto/helpers';

const TalkView = (props) => {
  const { content } = props;
  return (
    <Container id="view-wrapper talk-view">
      <h1 className="documentFirstHeading">
        <span className="type_of_talk">{content.type_of_talk.title} </span>
        {content.title}
      </h1>
      {content.description && (
        <p className="documentDescription">{content.description}</p>
      )}
      <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
      <Segment clearing>
        {content.speaker && <Header dividing>{content.speaker}</Header>}
        <p>{content.company || content.website}</p>
        {content.email && (
          <p>
            Email: <a href={`mailto:${content.email}`}>{content.email}</a>
          </p>
        )}
        <Image
          src={flattenToAppURL(content.image?.scales?.preview?.download)}
          size="small"
          floated="right"
          alt={content.image_caption}
          avatar
        />
        {content.speaker_biography && (
          <div
            dangerouslySetInnerHTML={{
              __html: content.speaker_biography.data,
            }}
          />
        )}
      </Segment>
    </Container>
  );
};
export default TalkView;

We use the component Image
We use flattenToAppURL to turn the Plone url of the image to the Volto url, e.g. it turns http://localhost:8080/Plone/talks/dexterity-for-the-win/@@images/9fb3d165-82f4-4ffa-804f-2afe1bad8124.jpeg into http://localhost:3000/talks/dexterity-for-the-win/@@images/9fb3d165-82f4-4ffa-804f-2afe1bad8124.jpeg.
Open the React Developer Tools in your browser and inspect the property image of TalkView and its property scale. If you look at the documentation for the serialization of image-fields you can find out where that information comes from.
To deal with talks without speaker image, we check for the existence of the image with content.image?.scales?.preview?.download. The expression with question marks returns undefined if content has no image key or content.image has no scales key and so on. ?. is the optional chaining operator.

Next we add the audience:

import React from 'react';
import { Container, Header, Image, Label, Segment } from 'semantic-ui-react';
import { flattenToAppURL } from '@plone/volto/helpers';

const TalkView = (props) => {
  const { content } = props;
  const color_mapping = {
    beginner: 'green',
    advanced: 'yellow',
    professional: 'purple',
  };

  return (
    <Container id="view-wrapper talk-view">
      <h1 className="documentFirstHeading">
        {content.type_of_talk.title || content.type_of_talk.token}:{' '}
        {content.title}
      </h1>
      {content.description && (
        <p className="documentDescription">{content.description}</p>
      )}
      {content.audience?.map((item) => {
        let color = color_mapping[item.token] || 'green';
        return (
          <Label key={item.token} color={color}>
            {item.title}
          </Label>
        );
      })}
      <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
      <Segment clearing>
        {content.speaker && <Header dividing>{content.speaker}</Header>}
        <p>{content.company || content.website}</p>
        {content.email && (
          <p>
            Email: <a href={`mailto:${content.email}`}>{content.email}</a>
          </p>
        )}
        <Image
          src={flattenToAppURL(content.image?.scales?.preview?.download)}
          size="small"
          floated="right"
          alt={content.image_caption}
          avatar
        />
        {content.speaker_biography && (
          <div
            dangerouslySetInnerHTML={{
              __html: content.speaker_biography.data,
            }}
          />
        )}
      </Segment>
    </Container>
  );
};
export default TalkView;

With {content.audience?.map(item => {...})} we iterate over the individual values of the choice field audience if that exists.
map is used to iterate over the array audience using an Arrow-function (=>) in which item is one item in audience.
The item is an Object like {'title': 'Advanced', 'token': 'advanced'}.
We map the available field values to colors and use green as a fallback.

As a last step we show the last few fields website and company, github and twitter:

import React from 'react';
import { flattenToAppURL } from '@plone/volto/helpers';
import { Container, Header, Image, Label, Segment } from 'semantic-ui-react';

const TalkView = (props) => {
  const { content } = props;
  const color_mapping = {
    Beginner: 'green',
    Advanced: 'yellow',
    Professional: 'purple',
  };

  return (
    <Container id="view-wrapper talk-view">
      <h1 className="documentFirstHeading">
        {content.type_of_talk.title || content.type_of_talk.token}:{' '}
        {content.title}
      </h1>
      {content.description && (
        <p className="documentDescription">{content.description}</p>
      )}
      {content.audience?.map((item) => {
        let audience = item.title || item.token;
        let color = color_mapping[audience] || 'green';
        return (
          <Label key={audience} color={color}>
            {audience}
          </Label>
        );
      })}
      {content.details && (
        <div dangerouslySetInnerHTML={{ __html: content.details.data }} />
      )}
      <Segment clearing>
        {content.speaker && <Header dividing>{content.speaker}</Header>}
        {content.website ? (
          <p>
            <a href={content.website}>
              {content.company || content.website}
            </a>
          </p>
        ) : (
          <p>{content.company}</p>
        )}
        {content.email && (
          <p>
            Email: <a href={`mailto:${content.email}`}>{content.email}</a>
          </p>
        )}
        {content.twitter && (
          <p>
            Twitter:{' '}
            <a href={`https://twitter.com/${content.twitter}`}>
              {content.twitter.startsWith('@')
                ? content.twitter
                : '@' + content.twitter}
            </a>
          </p>
        )}
        {content.github && (
          <p>
            Github:{' '}
            <a href={`https://github.com/${content.github}`}>
              {content.github}
            </a>
          </p>
        )}
        {content.image && (
          <Image
            src={flattenToAppURL(content.image.scales.preview.download)}
            size="small"
            floated="right"
            alt={content.image_caption}
            avatar
          />
        )}
        {content.speaker_biography && (
          <div
            dangerouslySetInnerHTML={{
              __html: content.speaker_biography.data,
            }}
          />
        )}
      </Segment>
    </Container>
  );
};
export default TalkView;

23.1. Summary¶

We created a view for a content type to display its data
We treated the case of missing values

Plone Training 2021 documentation

23. Volto View Component: A Default View for a "Talk"¶

23.1. Summary¶