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title | summary |
---|---|
Adding middleware | Add middleware to to extend query execution |
Extending the schema
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Adding middleware
Middleware is any piece of functionality that is interpolated into a larger process. A key feature of middleware is that it can be used with other middlewares in sequence and not have to worry about the order of execution.
In silverstripe-graphql
, middleware is used for query execution,
but could ostensibly be used elsewhere too if the API ever accomodates
such an expansion.
[notice] The middleware API in the silverstripe-graphql module is separate from other common middleware APIs in Silverstripe CMS, such as HTTPMiddleware. [/notice]
The signature for middleware is pretty simple:
public function process(array $params, callable $next)
$params
is an arbitrary array of data, much like an event object
passed to an event handler. The $next
parameter refers to the next
middleware in the chain.
Let's write a simple middleware that logs our queries as they come in.
class LoggingMiddleware implements Middleware
{
public function process(array $params, callable $next)
{
$query = $params['query'];
Injector::inst()->get(LoggerInterface::class)
->info('Query executed: ' . $query);
// Hand off execution to the next middleware
return $next($params);
}
}
Now we can register the middleware with our query handler:
SilverStripe\GraphQL\QueryHandler\QueryHandlerInterface.default:
class: SilverStripe\GraphQL\QueryHandler\QueryHandler
properties:
Middlewares:
logging: '%$MyProject\Middleware\LoggingMiddleware'