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126 lines
4.1 KiB
Markdown
126 lines
4.1 KiB
Markdown
# Prerequisites
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This documentation assumes your familiarity with GraphQL concepts. If it is not the case -
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first learn about GraphQL on [the official website](http://graphql.org/learn/).
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# Installation
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Using [composer](https://getcomposer.org/doc/00-intro.md), simply run:
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```sh
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composer require webonyx/graphql-php
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```
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# Upgrading
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We try to keep library releases backwards compatible. But when breaking changes are inevitable
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they are explained in [upgrade instructions](https://github.com/webonyx/graphql-php/blob/master/UPGRADE.md).
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# Install Tools (optional)
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While it is possible to communicate with GraphQL API using regular HTTP tools it is way
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more convenient for humans to use [GraphiQL](https://github.com/graphql/graphiql) - an in-browser
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IDE for exploring GraphQL APIs.
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It provides syntax-highlighting, auto-completion and auto-generated documentation for
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GraphQL API.
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The easiest way to use it is to install one of the existing Google Chrome extensions:
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- [ChromeiQL](https://chrome.google.com/webstore/detail/chromeiql/fkkiamalmpiidkljmicmjfbieiclmeij)
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- [GraphiQL Feen](https://chrome.google.com/webstore/detail/graphiql-feen/mcbfdonlkfpbfdpimkjilhdneikhfklp)
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Alternatively, you can follow instructions on [the GraphiQL](https://github.com/graphql/graphiql)
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page and install it locally.
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# Hello World
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Let's create a type system that will be capable to process following simple query:
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```
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query {
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echo(message: "Hello World")
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}
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```
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To do so we need an object type with field `echo`:
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```php
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<?php
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use GraphQL\Type\Definition\ObjectType;
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use GraphQL\Type\Definition\Type;
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$queryType = new ObjectType([
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'name' => 'Query',
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'fields' => [
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'echo' => [
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'type' => Type::string(),
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'args' => [
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'message' => Type::nonNull(Type::string()),
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],
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'resolve' => function ($root, $args) {
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return $root['prefix'] . $args['message'];
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}
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],
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],
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]);
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```
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(Note: type definition can be expressed in [different styles](type-system/index.md#type-definition-styles),
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but this example uses **inline** style for simplicity)
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The interesting piece here is **resolve** option of field definition. It is responsible for returning
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a value of our field. Values of **scalar** fields will be directly included in response while values of
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**composite** fields (objects, interfaces, unions) will be passed down to nested field resolvers
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(not in this example though).
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Now when our type is ready, let's create GraphQL endpoint file for it **graphql.php**:
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```php
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<?php
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use GraphQL\GraphQL;
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use GraphQL\Type\Schema;
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$schema = new Schema([
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'query' => $queryType
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]);
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$rawInput = file_get_contents('php://input');
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$input = json_decode($rawInput, true);
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$query = $input['query'];
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$variableValues = isset($input['variables']) ? $input['variables'] : null;
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try {
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$rootValue = ['prefix' => 'You said: '];
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$result = GraphQL::executeQuery($schema, $query, $rootValue, null, $variableValues);
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$output = $result->toArray();
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} catch (\Exception $e) {
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$output = [
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'errors' => [
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[
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'message' => $e->getMessage()
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]
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]
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];
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}
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header('Content-Type: application/json');
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echo json_encode($output);
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```
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Our example is finished. Try it by running:
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```sh
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php -S localhost:8000 graphql.php
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curl http://localhost:8080 -d '{"query": "query { echo(message: \"Hello World\") }" }'
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```
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Check out the full [source code](https://github.com/webonyx/graphql-php/blob/master/examples/00-hello-world) of this example
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which also includes simple mutation.
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Obviously hello world only scratches the surface of what is possible.
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So check out next example, which is closer to real-world apps.
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Or keep reading about [schema definition](type-system/index.md).
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# Blog example
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It is often easier to start with a full-featured example and then get back to documentation
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for your own work.
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Check out [Blog example of GraphQL API](https://github.com/webonyx/graphql-php/tree/master/examples/01-blog).
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It is quite close to real-world GraphQL hierarchies. Follow instructions and try it yourself in ~10 minutes.
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