mirror of
https://github.com/silverstripe/silverstripe-framework
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70 lines
2.1 KiB
Markdown
70 lines
2.1 KiB
Markdown
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---
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title: Adding middleware
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summary: Add middleware to to extend query execution
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---
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# Extending the schema
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[CHILDREN asList]
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[alert]
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You are viewing docs for a pre-release version of silverstripe/graphql (4.x).
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Help us improve it by joining #graphql on the [Community Slack](https://www.silverstripe.org/blog/community-slack-channel/),
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and report any issues at [github.com/silverstripe/silverstripe-graphql](https://github.com/silverstripe/silverstripe-graphql).
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Docs for the current stable version (3.x) can be found
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[here](https://github.com/silverstripe/silverstripe-graphql/tree/3)
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[/alert]
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## Adding middleware
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Middleware is any piece of functionality that is interpolated into
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a larger process. A key feature of middleware is that it can be used
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with other middlewares in sequence and not have to worry about the order
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of execution.
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In `silverstripe-graphql`, middleware is used for query execution,
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but could ostensibly be used elsewhere too if the API ever accomodates
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such an expansion.
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[notice]
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The middleware API in the silverstripe-graphql module is separate from other common middleware
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APIs in Silverstripe CMS, such as HTTPMiddleware.
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[/notice]
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The signature for middleware is pretty simple:
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```php
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public function process(array $params, callable $next)
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```
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`$params` is an arbitrary array of data, much like an event object
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passed to an event handler. The `$next` parameter refers to the next
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middleware in the chain.
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Let's write a simple middleware that logs our queries as they come in.
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```php
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class LoggingMiddleware implements Middleware
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{
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public function process(array $params, callable $next)
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{
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$query = $params['query'];
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Injector::inst()->get(LoggerInterface::class)
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->info('Query executed: ' . $query);
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// Hand off execution to the next middleware
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return $next($params);
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}
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}
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```
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Now we can register the middleware with our query handler:
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```yaml
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SilverStripe\GraphQL\QueryHandler\QueryHandlerInterface.default:
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class: SilverStripe\GraphQL\QueryHandler\QueryHandler
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properties:
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Middlewares:
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logging: '%$MyProject\Middleware\LoggingMiddleware'
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```
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