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The persisted query is a definition of the query for the frontend front-end component to import. We name this file the query name, minus the component name of the plugin we’re working with.

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• Create the persisted query file in the webapi/ajax/items.graphql with the following:

  Code Block

  languagegraphql

  query local_todo_items { local_todo_items { items { id title completed_at } } }

Create the backend

Now we need to create the PHP backend to handle the query.

• First we’ll create the directory for the query resolver by creating the following directory: /server/local/todo/classes/webapi/resolver/query

• Now let’s create the query resolver class, items.php in the directory we just created.:

  Code Block

  • Code Block
    language php
    <?php namespace local_todo\webapi\resolver\query; use core\webapi\execution_context; use core\webapi\query_resolver; use local_todo\entity\item; class items extends query_resolver { /** * @inheritDoc * @throws \coding_exception */ public static function resolve(array $args, execution_context $ec) { global $USER; $items = item::repository() ->where('user_id', $USER->id) ->order_by('id') ->get(); return ['items' => $items]; } }

  • In this file we’ve defined the query resolve and we’re using the ORM of local_todo to return a list of items.

• Now we create the type resolver directory /server/local/todo/classes/webapi/resolver/type/ and the type resolver for item item.php in the directory.:

  Code Block

  languagephp

  <?php namespace local_todo\webapi\resolver\type; use core\webapi\execution_context; use core\webapi\type_resolver; class item extends type_resolver { /** * @param string $field - The field being requested * @param $source - In the case, source will be our `item` entity class as it's what's returned from the query resolver * @param array $args * @param execution_context $ec * @return mixed|void */ public static function resolve(string $field, $source, array $args, execution_context $ec) { return $source->$field; } }

Testing queries and mutations

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