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Expression language

All definition config entries can use expression language but it must be explicitly triggered using the @= prefix. This bundle provides a set of registered functions and variables. For more details on expression syntax see the official documentation.

Contents

Registered functions

service

Signature: service(string $id): object|null | Alias: serv

Gets a service from the service container. Private services should be explicitly tagged to be accessible, see this section for more details.

Examples:

@=service('my_service').customMethod()

# Using the 'ser' alias
@=serv('my_service').customMethod()

# Using the FQCN for the service name (only works for public services).
# Note the double quotes.
@=serv("App\\Manager\\UserManager").someMethod()

# If using single quotes, you must use 4 slashes
@=serv('App\\\\Manager\\\\UserManager').someMethod()

parameter

Signature: parameter(string $name): mixed | Alias: param

Gets a parameter from the service container.

Examples:

@=parameter('kernel.debug')

# Using the 'param' alias
@=param('mailer.transport')

isTypeOf

Signature: isTypeOf(string $className): boolean

Checks if the value is instance of the given class name.

Example:

@=isTypeOf("App\\User\\User")

query

Signature: query(string $alias, ...$args): mixed | Alias: q

Calls a method on the tagged service overblog_graphql.resolver with $args

Examples:

# Using aliased resolver name
@=query('blog_by_id', value['blogID'])

# Using the 'q' alias and a FQCN::methodName.
# Note the double quotes.
@=q("App\\GraphQL\\Resolver\\UserResolver::findOne", args, info, context, value)

# If using single quotes, you must use 4 slashes
@=q('App\\\\GraphQL\\\\Resolver\\\\UserResolver::findOne', info, args)

mutation

Signature: mutation(string $alias, ...$args): mixed | Alias: m

Calls a method on the tagged service overblog_graphql.mutation passing $args as arguments.

Examples:

# Using aliased mutation name
@=mutation('remove_post_from_community', args.postId)

# Using the 'm' alias and a FQCN::methodName
# Note the double quotes.
@=m("App\\GraphQL\\Mutation\\PostMutation::findAll", args)

# If using single quotes, you must use 4 slashes
@=m('App\\\\GraphQL\\\\Mutation\\\\PostMutation::findAll', args)

arguments

Signature: arguments(array $mapping, mixed $data): mixed

Transforms and validates a list of arguments. See the Arguments Transformer section for more details.

Example:

@=arguments(['input' => 'MyInput'], ['input' => ['field1' => 'value1']])

globalId

Signature: globalId(string|int $id, string $typeName = null): string

Relay node globalId.

Example:

@=globalId(15, 'User')

fromGlobalId

Signature: fromGlobalId(string $globalId): array

Relay node globalId.

Example:

@=fromGlobalId(‘QmxvZzox’)

newObject

Signature: newObject(string $className, array $args = []): object

Creates a new class instance from given class name and arguments. Uses the following php code under the hood:

(new ReflectionClass($className))->newInstanceArgs($args)

See the official documentation for more details about the ReflectionClass::newInstanceArgs method.

Examples:

@=newObject("App\\Entity\\User", ["John", 15])

# Using inside another function (resolver)
@=resolver("myResolver", [newObject("App\\User\\User", [args])])

call

Signature: call(callable $target, array $args = []): mixed

Calls a function or a static method, passing $args to it as arguments.

Examples:

# Calling a static method using a FCN string
@=call("App\\Util\\Validator::email", ["arg1", 2])

# Calling a static method using an array callable
@=call(["App\\Util\\Validator", "email"], [args["email"]])

# Calling a function
@=call('array_merge', [args['array1'], args['array2']])

hasRole

Signature: hasRole(string $role): bool

Checks whether the logged in user has a certain role.

Example:

@=hasRole('ROLE_API')

hasAnyRole

Signature: hasAnyRole(string $role1, string $role2, ...string $roleN): bool

Checks whether the logged in user has at least one of the given roles.

Example:

@=hasAnyRole('ROLE_API', 'ROLE_ADMIN')

isAnonymous

Signature: isAnonymous(): bool

Checks whether the token is anonymous. Shorthand for:

AuthorizationChecker::isGranted('IS_AUTHENTICATED_ANONYMOUSLY')

Example:

@=isAnonymous()

isRememberMe

Signature: isRememberMe(): bool

Checks whether the token is remembered. Shorthand for :

AuthorizationChecker::isGranted('IS_AUTHENTICATED_REMEMBERED')

Example:

@=isRememberMe()

isFullyAuthenticated

Signature: isFullyAuthenticated(): bool

Checks whether the token is fully authenticated. Shorthand for:

AuthorizationChecker::isGranted('IS_AUTHENTICATED_FULLY')

Example:

@=isFullyAuthenticated()

isAuthenticated()

Signature: isAuthenticated(): bool

Checks whether the token is not anonymous. Shorthand for:

AuthorizationChecker::isGranted('IS_AUTHENTICATED_REMEMBERED') || AuthorizationChecker::isGranted('IS_AUTHENTICATED_FULLY')

Example:

@=isAuthenticated()

hasPermission

Signature: hasPermission(object $object, string $permission): bool

Checks whether logged in user has given permission for given object (requires symfony/acl-bundle to be installed).

Example:

# Using in combination with the 'service' function.
@=hasPermission(serv('user_repository').find(1), 'OWNER')

hasAnyPermission

Signature: hasAnyPermission(object $object, array $permission): bool

Checks whether the token has any of the given permissions for the given object

Example:

# Using in combination with the 'service' function
@=hasAnyPermission(service('my_service').getObject(), ['OWNER', 'ADMIN'])

getUser

Signature: getUser(): Symfony\Component\Security\Core\User\UserInterface|null

Returns the user which is currently in the security token storage.

Examples

@=getUser()

# Checking if user has particular name
@=getUser().firstName === 'adam'

getType

Signature: getType(string $alias): GraphQL\Type\Definition\Type|null

Returns a GraphQL type.

Examples

@=getType('Post')

Registered variables:

Variable Description Scope
object Refers to the value of the field for which access is being requested. For array object will be each item of the array. For Relay connection object will be the node of each connection edges. only available for config.fields.*.access with query operation or mutation payload type.
value The value returned by a previous resolver available in the resolve and access contexts
args An array of argument values of current resolver available in the resolve and access contexts
info A GraphQL\Type\Definition\ResolveInfo object of current resolver available in the resolve and access contexts
context context is defined by your application on the top level of query execution (useful for storing current user, environment details, etc) available in the resolve and access contexts
childrenComplexity Selection field children complexity only available in complexity context

Private services

It is not possible to use private services with the service function since this is equivalent to call the get method on the Service Container. In order to make private services accessible, they must be tagged with overblog_graphql.graphql_service.

Example:

App\MyPrivateService:
    public: false
    tags:
        - { name: overblog_graphql.graphql_service, alias: my_private_service }

Usage:

MyType:
    type: object
    config:
        fields:
            name:
                type: String!
                resolve: "@=service('my_private_service').formatName(value)"

To use a vendor private services:

$vendorPrivateServiceDef = $container->findDefinition(\Vendor\PrivateService::class);
$vendorPrivateServiceDef->addTag('overblog_graphql.graphql_service', ['alias' => 'vendor_private_service']);

Custom expression functions

Adding custom expression function is easy since all you need to do is create a tagged service. Expression functions can help user create simple resolver without having to leave config file, this also improves performance by removing a useless external resolver call.

Here is an example to add a custom expression equivalent to php json_decode:

<?php

namespace App\ExpressionLanguage;

use Overblog\GraphQLBundle\ExpressionLanguage\ExpressionFunction;

class JsonDecode extends ExpressionFunction
{
    public function __construct()
    {
        parent::__construct(
            'json_encode',
            function ($json, $assoc) {
                return sprintf('json_decode(%s, %s)', $json, $assoc);
            }
        );
    }
}

now register your service:

App\ExpressionLanguage\JsonDecode:
    tags: ['overblog_graphql.expression_function']

Now json_decode can be used in schema:

Object:
    type: object
    config:
        fields:
            name:
            type: String!
            resolve: "@=json_decode(value.json_data, true)['name']"

Tips: At last if this is not an answer to all your needs, the expression language service can be customized using bundle configuration.

Backslashes in expressions

Backslashes in expressions must be escaped by 2 or 4 backslasehs, depending on which quotes do you use.

When using single quotes as outer quotes, you must use double backslashes. e.g.:

...
resolve: '@=resolver("App\\GraphQL\\Resolver\\ResolverName::methodName")'
...

When using double quotes as outer quotes, you must use 4 backslashes, e.g.:

...
resolve: "@=resolver('App\\\\GraphQL\\\\Resolver\\\\ResolverName::methodName')"
...