Schema from code questions

[brmakana]

Hello,
I have a graphql-java application with a lot of custom code around translating my domain model to GraphQL types, and I'm interested in using DGS and the advanced feature "schema from code", but running into some stumbling blocks.

My code handles creating GraphQLOutputTypes and GraphQLInputTypes from my POJOs, but it looks like the DGS way revolves around working with a TypeDefinitionRegistry.

I'm wondering if anyone can provide some pointers on how to go from GraphQLOutputType/GraphQLInputType to something TypeDefinitionRegistry can understand? GraphQLObjectType does have a .getDefinition(), but TypeDefinitionRegistry takes an ObjectTypeExtensionDefinition, not an ObjectTypeDefinition. As well, I don't see any way to convert a GraphQLList..

Any pointers are welcome, I think DGS looks really exciting!

[srinivasankavitha]

Yeah, unfortunately, we don't currently have a way of adding ObjectType to the TypeDefinitionRegistry. We will need to add support for that.

[srinivasankavitha]

Have you tried using graphql.schema.GraphQLList.list?

String::class.java  -> list(Scalars.GraphQLString)
Integer::class.java -> list(Scalars.GraphQLInt)
Boolean::class.java -> list(Scalars.GraphQLBoolean)
Float::class.java -> list(Scalars.GraphQLFloat)
or
ListType(TypeName(nameOfType))

[srinivasankavitha]

Note that the above is to build an ObjectType, not an ObjectTypeExtensionDefinition, assuming the former is what you are asking about. If you want to build a list that is compatible with ObjectTypeDefinition and ObjectTypeExtensionDefinition, you can try using graphql.language.ListType

String::class.java  -> ListType(TypeName("String"))
Integer::class.java -> ListType(TypeName("Int"))
Boolean::class.java -> ListType(TypeName("Boolean"))
Float::class.java -> ListType(TypeName("Float"))
or
ListType(TypeName(nameOfType))

[brmakana]

I think I am more confused now.. previously with graphql-java, to create my schema programmatically looked like this:

              final GraphQLObjectType cat = GraphQLObjectType.newObject()
                .name("Cat")
                .field(GraphQLFieldDefinition.newFieldDefinition()
                    .name("name")
                    .type(GraphQLString)
                    .build())
                .build();
        final GraphQLObjectType query = GraphQLObjectType.newObject()
            .name("QueryType")
            .field(GraphQLFieldDefinition.newFieldDefinition()
                .name("getCats")
                .type(cat)
                )
            .build();
            
        final GraphQLSchema schema = GraphQLSchema.newSchema()
//            .codeRegistry() ignore datafetcher for this example
            .query(query)
            .build();            

with DGS, I can make a TypeDefinitionRegistry, but I'm confused on how to do the equivalent:

    @DgsTypeDefinitionRegistry
    public TypeDefinitionRegistry registry() {
        final TypeDefinitionRegistry typeDefinitionRegistry = new TypeDefinitionRegistry();
        final ObjectTypeExtensionDefinition cat = ObjectTypeExtensionDefinition.newObjectTypeExtensionDefinition()
            .name("Cat")
            .fieldDefinition(FieldDefinition.newFieldDefinition()
                .name("name")
                .type(new TypeName("String"))
                .build()
            )
            .build();
        typeDefinitionRegistry.add(cat);
        return typeDefinitionRegistry;
    }

this results in:

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [graphql.schema.GraphQLSchema]: Factory method 'schema' threw exception; nested exception is SchemaProblem{errors=[The extension 'Cat' type [@-1:-1] is missing its base underlying type]}

I appreciate your help!

[srinivasankavitha]

Can you try changing it to ObjectTypeDefinition instead of Extension? For everything to work together, you will need to add the Query type as well with the corresponding field. This should give you the schema shown below:

type Cat {
    name: String
}

@DgsTypeDefinitionRegistry
    public TypeDefinitionRegistry registry() {
        final TypeDefinitionRegistry typeDefinitionRegistry = new TypeDefinitionRegistry();
        final ObjectTypeExtensionDefinition cat = ObjectTypeDefinition.newObjectTypeDefinition()
            .name("Cat")
            .fieldDefinition(FieldDefinition.newFieldDefinition()
                .name("name")
                .type(new TypeName("String"))
                .build()
            )
            .build();
        typeDefinitionRegistry.add(cat);
        return typeDefinitionRegistry;
    }

For the Query type, you can then add an ObjectTypeExtensionDefinition to extend the base query type.

type Query extends {
    cat: Cat
}

ObjectTypeExtensionDefinition query = ObjectTypeExtensionDefinition.newObjectTypeExtensionDefinition().name("Query").fieldDefinition(
                FieldDefinition.newFieldDefinition().name("cat").type(new TypeName("Cat")).build()
        ).build();

We'll add more clarification around this in the docs so it's less confusing. Hope this helps.

[brmakana]

Ah, that worked! Thank you so much for the help!