Merge branch 'tugascript-mercurius-plugins'

Author: kamilmysliwiec

content/graphql/plugins.md

@@ -1,6 +1,4 @@
-### Plugins
-
-> warning **Warning** This chapter applies only to the `@nestjs/apollo` driver.
+### Plugins with Apollo
 
 Plugins enable you to extend Apollo Server's core functionality by performing custom operations in response to certain events. Currently, these events correspond to individual phases of the GraphQL request lifecycle, and to the startup of Apollo Server itself (read more [here](https://www.apollographql.com/docs/apollo-server/integrations/plugins/)). For example, a basic logging plugin might log the GraphQL query string associated with each request that's sent to Apollo Server.
 
@@ -48,3 +46,31 @@ GraphQLModule.forRoot({
 ```
 
 > info **Hint** The `ApolloServerOperationRegistry` plugin is exported from the `@apollo/server-plugin-operation-registry` package.
+
+#### Plugins with Mercurius
+
+Some of the existing mercurius-specific Fastify plugins must be loaded after the mercurius plugin (read more [here](https://mercurius.dev/#/docs/plugins)) on the plugin tree.
+
+> warning **Warning** [mercurius-upload](https://github.com/mercurius-js/mercurius-upload) is an exception and should be registered in the main file.
+
+For this, `MercuriusDriver` exposes an optional `plugins` configuration option. It represents an array of objects that consist of two attributes: `plugin` and its `options`. Therefore, registering the [cache plugin](https://github.com/mercurius-js/cache) would look like this:
+
+```typescript
+GraphQLModule.forRoot({
+  driver: MercuriusDriver,
+  // ...
+  plugins: [
+    {
+      plugin: cache,
+      options: {
+        ttl: 10,
+        policy: {
+          Query: {
+            add: true
+          }
+        }
+      },
+    }
+  ]
+}),
+```