Generate client from schema

[huehnerlady]

Hi,

We are using spring-mvc and therefore cannot use the graphql-kotlin-server dependency. What we did instead is to use the lib com.expediagroup:graphql-kotlin-schema-generator to generate our schema, and create the GraphQL-endpoint manually. This works really well and we are very happy with the lib overall ❤️ .

Now we would like to create some contracttests to ensure that our model etc does not break for the client.
We would like to use graphql-kotlin for it as we use it in other services and like the easy usage. BUT now we have the problem, that we do not have a file an endpoint or anything in that regard to generate the client code in gradle.

Is there maybe another way to generate the client?

[dariuszkuc]

Hello 👋
You should be able to generate your schema file using graphqlGenerateSDL task (https://expediagroup.github.io/graphql-kotlin/docs/plugins/gradle-plugin-usage#generating-sdl-example) which you can then use for generating your client.

[huehnerlady]

Thank your for your hint.

I tried this but now I seem to have the Problem, that we use interfaces for our beans and therefore have multiple implementations with different spring-conditionals attached to it. When I then attach the Mutation interface to our interface, I get the gradle error

 > A failure occurred while executing com.expediagroup.graphql.plugin.gradle.actions.GenerateSDLAction
      > Conflicting field names in schema generation [type : Mutation(class: class de.foo.graphql.MutationImpl), field name: update]

part of the debug log

2021-06-24T10:57:21.891+0200 [DEBUG] [org.gradle.api.Task] submitting work item to generate SDL for the supported packages = [de.europace.kreditsmart.api.vorgang, de.foo.api.graphql, de.foo.graphql]
2021-06-24T10:57:21.986+0200 [WARN] [generateSDL] No SchemaGeneratorHooksProvider were found, defaulting to NoopSchemaGeneratorHooks
2021-06-24T10:57:22.412+0200 [DEBUG] [generateSDL] Generating schema using hooks = NoopSchemaGeneratorHooks
2021-06-24T10:57:22.412+0200 [DEBUG] [generateSDL]   query classes = [class de.foo.graphql.FooQuery]
2021-06-24T10:57:22.412+0200 [DEBUG] [generateSDL]   mutation classes = [class de.foo.graphql.Mutation, class de.foo.graphql.MutationImpl, class de.foo.graphql.MutationMock]
2021-06-24T10:57:22.412+0200 [DEBUG] [generateSDL]   subscription classes = []

Another question would be how we would use this file in our spring-server.
If we use a generated SDL file for the clients I would argue with the pattern 'eat your own dogfood' we would also want to use it in our code as well.

Currently we are having the following setup:

  @Bean
  fun graphql(fooQuery: FooQuery, mutation: Mutation): GraphQL {
    val schema = toSchema(
        config = SchemaGeneratorConfig(
            supportedPackages = listOf("de.foo.api.vorgang", "de.foo.api.graphql")
        ),
        queries = listOf(TopLevelObject(fooQuery)),
        mutations = listOf(TopLevelObject(mutation))
    )
    log.info(schema.print())
    return GraphQL.newGraphQL(schema).build()
  }

How would we achieve this using the sdl file?

[dariuszkuc]

re: conditional queries/mutations - SDL generation is unaware of anything Spring specific and has to be deterministic. You will need to create custom hooks provider that would know how to generate your schema (i.e. which queries/mutations to pick -> depending on your setup this might be somewhat complex)

re: dogfooding - you can use the generated SDL to generate your test client that you can then use in your integration tests

[huehnerlady]

Yeah we do it the way now to not use the SDL in the service just for generating the client, not perfect, but works for us, thanks for your help :)