strictScalars and scalars map for graphql source codegen

[leemhenson]

Is your feature request related to a problem? Please describe.

I am stitching together several graphql sources. They define custom scalar types, and I would like to be able to tell the codegen process what the equivalent typescript type should be for those scalars via the scalars map as documented here.

I would then additionally like to be able to enable the strictScalars flag so that the build process fails if I haven't provided a Typescript mapping for a scalar.

Describe the solution you'd like

I guess this would make sense in the source config:

sources:
  - name: MyGraphQLApi
    handler:
      graphql:
        endpoint: http://my-service-url:3000/graphql
        operationHeaders:
          Authorization: Bearer {env.MY_API_TOKEN}
        scalars:
          ScalarTypeA: string
          ScalarTypeB: number
        strictScalars: true

Describe alternatives you've considered

Leaving it as it is, which applies the type any to any unknown scalar. This isn't great as it will lead to bugs.

[leemhenson]

Perhaps it make make things a little more future-proof if the graphql source config block just forwarded a codegen config block onto graphql-codegen directly, e.g.:

sources:
  - name: MyGraphQLApi
    handler:
      graphql:
        endpoint: http://my-service-url:3000/graphql
        operationHeaders:
          Authorization: Bearer {env.MY_API_TOKEN}
        codegen:
          scalars:
            ScalarTypeA: string
            ScalarTypeB: number
          strictScalars: true

[ardatan]

You can add custom codegen config like below;

codegen:
  scalars:
    ...

[leemhenson]

Hi. That works for the types emitted for the meshed schema, but it doesn't emit config for the source schemas.

e.g. say in my source schema there is scalar DateTime, if i add:

codegen:
    scalars:
        DateTime: string

then in the emitted .mesh/index.ts I get:

// at the top of the file

export type Scalars = {
    ID: string;
    String: string;
    Boolean: boolean;
    Int: number;
    Float: number;
    DateTime: string;  // <-- looks good
}

// lower down in the file

namespace MySourceTypes {
  export type Scalars = {
    ID: string;
    String: string;
    Boolean: boolean;
    Int: number;
    Float: number;
    DateTime: any;  // <-- uh oh
  }
}

If I try to add a codegen yaml block inside the graphql source block then I get errors about excess properties not being allowed.

[ardatan]

For now, it is not possible to configure InContext SDK type generation.