[TypeScript] Add __typename to typings

I use GraphQL interfaces. When querying for a field that might be any type implementing a specific interface I need to know which implementation it is, for this I currently use __typename.

Would be great if you would add the __typename field for all typings (should probably be an optional field).

[leebenson]

Keep in mind that for example apollo-client always selects __typename even if it’s not specified in the query.

This is true, but because GraphQL Code Generator doesn’t include __typename on individual fields, TS only reports it being available at the top-level.

Example –

Given something like this:

fragment Source on Source {
  __typename  # <-- explicitly requested on the fragment
  id
  name
  type
}

query Builder(
  $source: Boolean!
  $sourceId: ID!
) {

  # ... other types omitted for brevity...

  source: node(id: $sourceId) @include(if: $source) {
    __typename # <-- explicitly requested at the root-level, e.g. same as the fragment
    ...BuilderSource
  }
}

I get __typename on the root-level query:

But not on the individual source field,

TL;DR - We should get __typename on fields, too.

[dotansimha]

You are right, @leebenson , I’m working on a fix. Thank you!