GraphQLClientError et al should be sourced from a separate package

[ddevault]

Hi! I'm running into a small frustration when experimenting with ariadne-codegen. Types like GraphQLClientError are just copied as-is from Ariadne into the generated namespace, resulting in something like foo.graphql_client.GraphQLClientError as the fully qualified type. For my use-case, we have standardized error handling throughout several different projects which each use their own generated GraphQL client -- but it's not straightforward to feed these exceptions into common error handling code (to, for instance, catch the errors and translate them into error feedback on HTML form inputs). I end up doing something like this in my generic code:

class ErrorHandlingContextThingy:
    def __enter__(self):
        pass

    def __exit__(self, exc_type, exc_value, traceback):
        if exc_type is None:
            return

        is_gql = exc_type.__name__ == "GraphQLClientGraphQLMultiError"

        if not is_gql:
            raise exc_value

        for err in exc_value.errors:
            # ...process the errors...

Because I don't know the fully qualified name of the exception in advance.

It seems to me that some features common to all GraphQL clients, such as the set of standard exceptions, and perhaps the BaseClient as well, would benefit from being sourced from a common graphql_client package (or similar) rather than being copied into the generated code.

Thoughts?

[ddevault]

I'm going to start working on this soon. I see three possible approaches:

1. An installable module is added to ariadne-codegen which must be present at runtime to provide these types
2. A secondary package is developed and uploaded to pypi which provides these types and becomes a runtime dependency
3. A new option is introduced to the config file to source the exception types from an arbitrary module'

I suppose option 3 is the least controversial. Anyone have feedback on the approach? Absent feedback I will move forward with option 3 and prepare a pull request.

[ddevault]

It occurs to me, researching this again later, that graphql.error.GraphQLError from graphql-core is the obvious type to use here. Of course that introduces a runtime dependency on graphql-core but that hardly seems unreasonable.