graphql-api-construct addResolver for Query failing

[jimjiminyjimjim]

Amplify CLI Version

12.2.5

Question

I can successfully add Appsync JS resolvers for any field in my api schema. However, if I try and add my own resolver for a Query such as getRegistryItem or listRegistryItems I receive the following error on deploy:

Resource handler returned message: "Resource already exists: arn:aws:appsync:eu-west-2::apis/*********/types/Query/resolvers/getRegistryItem"

Here is my resolver code:

    const registryItemTable = Table.fromTableName(
      this,
      "RegistryItemTable",
      amplifyApi.resources.cfnResources.cfnTables["RegistryItem"].ref
    );

    const registryItemDS = amplifyApi.addDynamoDbDataSource(
      "RegistryItemDataSource",
      registryItemTable
    );

    amplifyApi.addResolver("ListRegistryItems", {
      dataSource: registryItemDS,
      typeName: "Query",
      fieldName: "listRegistryItems",
      code: AppsyncCode.fromAsset(
        path.join(__dirname, "resolvers/registryItem/query", "listRegistryItems.js")
      ),
      runtime: FunctionRuntime.JS_1_0_0,
    });
    

Am I doing something wrong? I've tried disabling the creation of the query in the schema but then I get the following error:

"No field named listRegistryItems found on type Query"

[jimjiminyjimjim]

UPDATE:

After looking more at this I have worked out how to do the following:

• extend the generated resolvers by inserting a VTL template into specific slots (either "init" | "preAuth" | "auth" | "postAuth" | "preDataLoad" | "postDataLoad" | "finish") with this:

  const amplifyApi = new AmplifyGraphqlApi(this, "AmplifyCdkGraphQlApi", {
      //...rest of graphql definition
      functionSlots: [queryFunctionSlot]
      

• override an after mapping or before mapping using something like this (which overrides the final response mapping template in the generated pipeline resolver in this case:

    const existingResolverResource = amplifyApi.resources.cfnResources.cfnResolvers['Query.listRegistryItems'];
    existingResolverResource.addPropertyOverride('ResponseMappingTemplate', `$util.toJson($ctx.result)`);
    

But I don't seem to be able to override or add an appSync resolver for the main data request or response function of a generated query by the api definition?

Using addResolver seems to work on listRegistryItems if I define a custom Query or Mutation in the schema and disable the generated one like this but ideally I'd like to do something to override the generated Query.listRegistryItems.req.vtl that I would do normally do with Amplify:

type RegistryItem
  @model #(queries: { list: null })
  ) {
  id: ID!
  name: String
  version: Int
}

type Query {
  listRegistryItems(id: ID!): String
 }

Any further information on this would be much appreciated.