This library builds a request for sending to a GraphQL server.

GraphQL is a query language to easy request data from remote web servers. There are several pros for using GraphQL instead of REST like

• decreasing request amount
• saving traffic in payload
• avoid backend changes on changing client requested data

For a full description see How to GraphQL.

The schema of GraphQL is defined by two easy attributes:

• Types
• Arguments

Type define a structured requested data object. Arguments can define these types.

A type forum can have posts, which has authors and a title. If you want to receive all author ant post title information as response your request can look like this:

{
  forum {
    posts {
      authors,
      title
    }
  }
}

To specify your requested data for crawling only the last 5 posts you can modify your request like this:

{
  forum {
    posts(last: 5) {
      authors,
      title
    }
  }
}

GraphQL requested data can complex as you want:

{
  forum {
    posts(last: 5) {
      authors(registration: {date: "2019-08-08"}, visible: true) {
        surname,
        prename(startingWith: "a"),
        birthday
      },
      title
    },
    users(last: 10, sort: "registrationDate", order: "DESC")
  }
}

This library helps building this payload structure without any string concatenation or other strange ideas.

To create following request payload

{
  field {
    search(criteria: {start: "2019-08-23"}) {
      errors {
        code
        type
        description
      }
      id
    }
  }
}

you need to execute following PHP code

<?php
declare(strict_types=1);

use GraphQL\RequestBuilder\Argument;
use GraphQL\RequestBuilder\RootType;
use GraphQL\RequestBuilder\Type;

$searchType = (new Type('search'))
    ->addArgument(new Argument('criteria', new Argument('start', '2019-08-23')))
    ->addSubTypes([
        (new Type('errors'))->addSubTypes(['code', 'type', 'description']),
        'id'
    ]
);

echo (string) (new RootType('field'))->addSubType($searchType);

Its also possible to build complex types. This code examples show you how to do this.

Sometimes you want to have arrays with complex Argument types, like the following example.

{
  persons: [
    {age: 30},
    {age: 20},
    {age: 12}
  ]
}

For this concept you can use the class ArrayArgument which give the possibility to add Arguments to an array.

<?php
declare(strict_types=1);

use GraphQL\RequestBuilder\Argument;
use GraphQL\RequestBuilder\ArrayArgument;

$persons = new ArrayArgument(
    'persons',
    [new Argument('age', 30), new Argument('age', 20), new Argument('age', 12)]
);

The example above works if you have an array with only one Argument: every person only has one Argument, the age. If you want to have more Arguments you need to create an Argumentwith an empty name.

{
  persons: [
    {
      name: "Hans",
      age: 30
    },
    {
      name: "Max",
      age: 20
    }
  ]
}

Your PHP code should look like this:

<?php
declare(strict_types=1);

use GraphQL\RequestBuilder\Argument;
use GraphQL\RequestBuilder\ArrayArgument;

$person1 = new ArrayArgument('', [new Argument('name', 'Hans'), new Argument('age', 30)]);
$person2 = new ArrayArgument('', [new Argument('name', 'Max'), new Argument('age', 20)]);

$persons = new ArrayArgument('persons', [$person1, $person2]);

To create enum arguments it should look like this:

<?php
declare(strict_types=1);

use GraphQL\RequestBuilder\EnumArgument;

$person1 = new EnumArgument('EnumAttribute', 'EnumValue');