Amplify GraphQL -> C# Code Generation using `graphql-codegen`

amplify_shim.graphql

# Taken from https://github.com/dotansimha/graphql-code-generator/discussions/4311

scalar AWSTime
scalar AWSDate
scalar AWSDateTime
scalar AWSTimestamp
scalar AWSEmail
scalar AWSJSON
scalar AWSURL
scalar AWSPhone
scalar AWSIPAddress
scalar BigInt
scalar Double

directive @aws_subscribe(mutations: [String!]!) on FIELD_DEFINITION

# Allows transformer libraries to deprecate directive arguments.
directive @deprecated(reason: String!) on INPUT_FIELD_DEFINITION | ENUM

directive @aws_auth(cognito_groups: [String!]!) on FIELD_DEFINITION
directive @aws_api_key on FIELD_DEFINITION | OBJECT
directive @aws_iam on FIELD_DEFINITION | OBJECT
directive @aws_oidc on FIELD_DEFINITION | OBJECT
directive @aws_cognito_user_pools(
  cognito_groups: [String!]
) on FIELD_DEFINITION | OBJECT

codegen.yml

schema: 
  - amplify\backend\api\my_project\build\schema.graphql 
  - amplify_shim.graphql 
generates:
  AmplifyGraphQL.cs:
    config:
      scalars:
        AWSDateTime: DateTimeOffset
        AWSDate: DateOnly
        AWSEmail: string
        AWSJSON: string
        AWSURL: string
        AWSTimestamp: long
    plugins:
      - c-sharp

package.json

// Run using `npm install` the first time, then `npm run graphql-codegen` after that. 
{
  "scripts":{
    "graphql-codegen": "graphql-codegen"
  },
  "devDependencies": {
    "@graphql-codegen/c-sharp": "5.0.0",
    "@graphql-codegen/cli": "5.0.0"
  }
}

Hopefully this helps people. Discussion around Amplify GraphQL dotansimha/graphql-code-generator#4311

Issues I had:

Unknown type: "AWSDateTime".
Reason: AWS scalars are not defined in the generated amplify graphql schema. The extra amplify_shim.graphql schema helps with this.

✖ Cannot use GraphQLScalarType "AWSDate" from another module or realm
Reason: The globally installed graphql-js was different from the locally installed one. Adding an npm run command fixed it.