Tips & tricks#

Debugging the generated code#

By default, the generated PHP code is put into obfuscated classnames and filenames to prevent poisoning the search tools within IDEs. Without this, you can search for something like "Page" in your IDE and get both a generated GraphQL type (probably not what you want) and a SiteTree subclass (more likely what you want) in the results and have no easy way of differentiating between the two.

When debugging, however, it's much easier if these classnames are human-readable. To turn on debug mode, add DEBUG_SCHEMA=1 to your environment file. The classnames and filenames in the generated code directory will then match their type names.

In live mode, full obfuscation kicks in and the filenames become unreadable. You can only determine the type they map to by looking at the generated classes and finding the // @type:<typename> inline comment, e.g. // @type:Page.

This obfuscation is handled by the NameObfuscator interface.

There are various implementations:

• NaiveNameObfuscator: Filename/Classname === Type name (debug only)
• HybridNameObfuscator: Filename/Classname is a mix of the typename and a md5 hash (default).
• HashNameObfuscator: Filename/Classname is a md5 hash of the type name (non-dev only).

Getting the type name for a model class#

Often times, you'll need to know the name of the type given a class name. There's a bit of context to this.

Getting the type name from within your app#

If you need the type name during normal execution of your app, e.g. to display in your UI, you can rely on the cached typenames, which are persisted alongside your generated schema code.

use SilverStripe\GraphQL\Schema\SchemaBuilder;

SchemaBuilder::singleton()->read('default')->getTypeNameForClass($className);

Persisting queries#

A common pattern in GraphQL APIs is to store queries on the server by an identifier. This helps save on bandwidth, as the client doesn't need to put a fully expressed query in the request body - they can use a simple identifier. Also, it allows you to whitelist only specific query IDs, and block all other ad-hoc, potentially malicious queries, which adds an extra layer of security to your API, particularly if it's public.

To implement persisted queries, you need an implementation of the PersistedQueryMappingProvider interface. By default three are provided, which cover most use cases:

• FileProvider: Store your queries in a flat JSON file on the local filesystem.
• HTTPProvider: Store your queries on a remote server and reference a JSON file by URL.
• JSONStringProvider: Store your queries as hardcoded JSON

Configuring query mapping providers#

All of these implementations can be configured through Injector.

FileProvider#

SilverStripe\Core\Injector\Injector:
  SilverStripe\GraphQL\PersistedQuery\PersistedQueryMappingProvider:
    class: SilverStripe\GraphQL\PersistedQuery\FileProvider
    properties:
     schemaMapping:
       default: '/var/www/project/query-mapping.json'

A flat file in the path /var/www/project/query-mapping.json should contain something like:

{"someUniqueID":"query{validateToken{Valid Message Code}}"}

HTTPProvider#

SilverStripe\Core\Injector\Injector:
  SilverStripe\GraphQL\PersistedQuery\PersistedQueryMappingProvider:
    class: SilverStripe\GraphQL\PersistedQuery\HTTPProvider
    properties:
     schemaMapping:
       default: 'https://www.example.com/myqueries.json'

A flat file at the URL https://www.example.com/myqueries.json should contain something like:

{"someUniqueID":"query{readMembers{Name+Email}}"}

JSONStringProvider#

SilverStripe\Core\Injector\Injector:
  SilverStripe\GraphQL\PersistedQuery\PersistedQueryMappingProvider:
    class: SilverStripe\GraphQL\PersistedQuery\HTTPProvider
    properties:
     schemaMapping:
       default: '{"myMutation":"mutation{createComment($comment:String!){Comment}}"}'

The queries are hardcoded into the configuration.

Requesting queries by identifier#

To access a persisted query, simply pass an id parameter in the request in lieu of query.

GET https://www.example.com/graphql?id=someID

Query caching (caution: EXPERIMENTAL)#

The QueryCachingMiddleware class is an experimental cache layer that persists the results of a GraphQL query to limit unnecessary calls to the database. The query cache is automatically expired when any DataObject that it relies on is modified. The entire cache will be discarded on ?flush requests.

To implement query caching, add the middleware to your QueryHandler

SilverStripe\Core\Injector\Injector:
  SilverStripe\GraphQL\QueryHandler\QueryHandlerInterface.default:
    class: SilverStripe\GraphQL\QueryHandler\QueryHandler
    properties:
      Middlewares:
        cache: '%$SilverStripe\GraphQL\Middleware\QueryCachingMiddleware'

And you will also need to apply the QueryRecorderExtension extension to all DataObjects:

SilverStripe\ORM\DataObject:
  extensions:
    - SilverStripe\GraphQL\Extensions\QueryRecorderExtension

Schema introspection#

Some GraphQL clients such as Apollo Client require some level of introspection into the schema. The SchemaTranscriber class will persist this data to a static file in an event that is fired on completion of the schema build. This file can then be consumed by a client side library like Apollo.

{
   "data":{
      "__schema":{
         "types":[
            {
               "kind":"OBJECT",
               "name":"Query",
               "possibleTypes":null
            }
            // etc ...
         ]
      }
   }
}

By default, the file will be stored in public/_graphql/.

If you need these types for your own uses, add a new handler:

SilverStripe\Core\Injector\Injector:
  SilverStripe\EventDispatcher\Dispatch\Dispatcher:
    properties:
      handlers:
        graphqlTranscribe:
          on: [ graphqlSchemaBuild.mySchema ]
          handler: '%$SilverStripe\GraphQL\Schema\Services\SchemaTranscribeHandler'

This handler will only apply to events fired in the mySchema context.