Correct Usage of Query Projections Using Kotlin Codegen

[theovier]

Hi,

I'm using Kotlin and I'm trying to craft queries/mutations for my tests with the help of the DgsClient generated by the Kotlin Codegen. I followed the example of the Query Projections section and run into the problem that my compiler complains that it expects a Function invocation, i.e. :compileTestKotlin Error: Function invocation 'id()' expected.

How do I correctly call the DgsClient.buildQuery (or buildMutation for that part) function with my generated Projection?

I've come up with a minimal example:

package com.demeter.backend.mutations

import com.demeter.generated.DgsClient
import org.junit.jupiter.api.Test
import org.springframework.boot.test.context.SpringBootTest

@SpringBootTest
class RecipeTests {

    @Test
    fun `not working`() {
        val query =
            DgsClient.buildQuery {
                someRecipe {
                    id // :compileTestKotlin Error: Function invocation 'id()' expected
                }
            }
    }

    @Test
    fun working() {
        val query = DgsClient.buildQuery { simple } // works just fine as the 'simple' query just returns a string
    }
}

schema.graphql

# ...
type Query {
    someRecipe: Recipe
    simple: String
}

type Recipe {
    id: ID!,
    title: String!
}

generated files by dgs-codegen

public object DgsClient {
  public fun buildQuery(_projection: QueryProjection.() -> QueryProjection): String =
      GraphQLProjection.asQuery(OperationDefinition.Operation.QUERY, QueryProjection(), _projection)

  public fun buildMutation(_projection: MutationProjection.() -> MutationProjection): String =
      GraphQLProjection.asQuery(OperationDefinition.Operation.MUTATION, MutationProjection(),
      _projection)
}

public class RecipeProjection : GraphQLProjection() {
  public val id: RecipeProjection
    get() {
      field("id")
      return this
    }

  public val title: RecipeProjection
    get() {
      field("title")
      return this
    }
}

public class RecipeProjection<PARENT extends BaseSubProjectionNode<?, ?>, ROOT extends BaseSubProjectionNode<?, ?>> extends BaseSubProjectionNode<PARENT, ROOT> {
  public RecipeProjection(PARENT parent, ROOT root) {
    super(parent, root, java.util.Optional.of("Recipe"));
  }
  
  public RecipeProjection<PARENT, ROOT> id() {
    getFields().put("id", null);
    return this;
  }

  public RecipeProjection<PARENT, ROOT> title() {
    getFields().put("title", null);
    return this;
  }
}

public class QueryProjection : GraphQLProjection() {
  public val simple: QueryProjection
    get() {
      field("simple")
      return this
    }

  public fun someRecipe(_projection: RecipeProjection.() -> RecipeProjection): QueryProjection {
    field("someRecipe", RecipeProjection(), _projection)
    return this
  }
}

build.gradle.kts

plugins {
    // ...
    kotlin("jvm") version "1.9.22"
    id("com.netflix.dgs.codegen") version "6.1.4"
}

// ...

tasks.withType<com.netflix.graphql.dgs.codegen.gradle.GenerateJavaTask> {
    generateClient = true
    generateKotlinClosureProjections = true
    generateKotlinNullableClasses = true
    language = "kotlin"
    packageName = "com.demeter.generated"
}

Kind regards,
Theo

[theovier]

Turns out, that was indeed the correct usage. I needed to delete my generated folder and re-generate the files. Now, it works like a charm. Sorry for the fuss :)

[srinivasankavitha]

Glad you were able to resolve it! Thanks for the update.