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v2.4 Handling Relations to Collections
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Handling Relations to Collections

Let’s consider an API exposing Person and Book resources linked by a many-to-many relation (through the authors property).

This API uses the following PHP code:

<?php
// api/src/Entity/Person.php

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ApiResource
 * @ORM\Entity
 */
class Person
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue
     * @ORM\Id
     */
    public $id;

    /**
     * @ORM\Column
     */
    public $name;
}
<?php
// api/src/Entity/Book.php

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ApiResource
 * @ORM\Entity
 */
class Book
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue
     * @ORM\Id
     */
    public $id;

    /**
     * @ORM\ManyToMany(targetEntity="Person")
     */
    public $authors;

    public function __construct()
    {
        $this->authors = new ArrayCollection();
    }
}

The admin handles this to-many relation automatically!

Customizing a Property

Let’s customize the components used for the authors property, to display them by their ’name’ instead of their ‘id’ (the default behavior).

import React, { Component } from 'react';
import { ReferenceArrayField, SingleFieldList, ChipField, ReferenceArrayInput, SelectArrayInput } from 'react-admin';
import { AdminBuilder, hydraClient } from '@api-platform/admin';
import parseHydraDocumentation from '@api-platform/api-doc-parser/lib/hydra/parseHydraDocumentation';

const entrypoint = 'https://demo.api-platform.com';

export default class extends Component {
  state = { api: null }

  componentDidMount() {
    parseHydraDocumentation(entrypoint).then(({api}) => {
        const books = api.resources.find(({ name }) => 'books' === name)
        const authors = books.fields.find(({ name }) => 'authors' === name)

        // Set the field in the list and the show views
        authors.field = props => (
          <ReferenceArrayField source={authors.name} reference={authors.reference.name} key={authors.name} {...props}>
            <SingleFieldList>
              <ChipField source="name" key="name"/>
            </SingleFieldList>
          </ReferenceArrayField>
        );

        // Set the input in the edit and create views
        authors.input = props => (
          <ReferenceArrayInput source={authors.name} reference={authors.reference.name} label="Authors" key={authors.name} {...props} allowEmpty>
            <SelectArrayInput optionText="name"/>
          </ReferenceArrayInput>
        );

        this.setState({ api });
      }
    )
  }

  render() {
    if (null === this.state.api) return <div>Loading...</div>;

    return <AdminBuilder api={ this.state.api } dataProvider={ hydraClient(this.state.api) }/>
  }
}

Customizing an Icon

Now that our authors property is displaying the name instead of the ‘id’, let’s change the icon shown in the list menu.

Just add an import statement from @material-ui for adding the icon - in this case, a user icon:

import UserIcon from '@material-ui/icons/People';

and add it to the authors.icon property.

The code for customizing only the icon will be:

import React, { Component } from 'react';
import { AdminBuilder, hydraClient } from '@api-platform/admin';
import parseHydraDocumentation from '@api-platform/api-doc-parser/lib/hydra/parseHydraDocumentation';
import UserIcon from '@material-ui/icons/People';

const entrypoint = 'https://demo.api-platform.com';

export default class extends Component {
  state = { api: null }

  componentDidMount() {
    parseHydraDocumentation(entrypoint).then(({api}) => {
        const authors = books.fields.find(({ name }) => 'authors' === name)

        // Set the icon
        authors.icon = UserIcon
       
        this.setState({ api });
      }
    )
  }

  render() {
    if (null === this.state.api) return <div>Loading...</div>;

    return <AdminBuilder api={ this.state.api } dataProvider={ hydraClient(this.state.api) }/>
  }
}

Using an Autocomplete Input for Relations

We’ll make one last improvement to our admin: transforming the relation selector we just created to use autocompletion.

Start by adding a “partial search” filter on the name property of the Book resource class.

# api/config/services.yaml
services:
    person.search_filter:
        parent: 'api_platform.doctrine.orm.search_filter'
        arguments: [ { name: 'partial' } ]
        # Uncomment only if you don't use autoconfiguration
        #tags: ['api_platform.filter']
<?php
// api/src/Entity/Person.php
// ...

/**
 * @ApiResource(attributes={"filters"={"person.search_filter"}})
 * @ORM\Entity
 */
class Person
{
    // ...
}

Then edit the configuration of API Platform Admin to pass a filterToQuery property to the ReferenceArrayInput component.

  componentDidMount() {

    // ...

    // Set the input in the edit and create views
      authors.input = props => (
        <ReferenceArrayInput source={authors.name} reference={authors.reference.name} label="Authors" key={authors.name} filterToQuery={searchText => ({ name: searchText })} {...props} allowEmpty>
          <SelectArrayInput optionText="name"/>
        </ReferenceArrayInput>
      );

    // ...
  }

The autocomplete field should now work properly!

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