Option for externally defined enums

[jakmeier]

Allow to deserialize GraphQL enums into user defined Rust enums, as described in #358

[jakmeier]

Here is a first suggestion to add the feature requested in #358. The implementation is very simple. Just don't generate enums if it is in the specified list of external enums. Most of the changes are for adding the option and parsing it. Looking forward to your input on this when you have time to take a look.

Example usage:

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "api/schema.json",
    query_path = "api/queries/buildings_query.graphql",
    extern_enums("BuildingType")
)]
pub struct BuildingsQuery;

I tested this with my game and 7 queries which use 1-2 enums each. It works as intended for me. As expected, I was able to remove hundreds LOC of boiler-plate code as a result of this. :-)

This is intentionally a minimal change to get the feature done. I guess from my point of view, this is all I really need. But I'm happy to add more bells and whistles, like the option to rename the type name, if that is desired.

What I'm most uncertain about in the current implementation is the error handling. I tried to keep it in line with existing code. It seems that errors due to incorrectly formatted attributes are ignored silently and compilation proceeds as if the attributes were not defined. This is what the new extern_enums attribute does now, too. Let me know if you prefer something else.

Also, please let me know if anything else I should do for the PR, such as writing changelogs or documentation.

[tomhoule]

Looks good! A test would be great if you have time for it, otherwise I'll write one next time I have a few hours to work on graphql-client.

[tomhoule]

I assume this just works because the generated modules already use super::*?

[jakmeier]

Yes, it very much relies on that. It's simple and it works. :) Unless you think use super::* might be removed in the future, I don't really see this as a problem. But happy to look into alternatives if you think there could be a cleaner solution.

[jakmeier]

Looks good! A test would be great if you have time for it, otherwise I'll write one next time I have a few hours to work on graphql-client.

Absolutely, I will create a test shortly

[jakmeier]

I added two basic tests.

Checking the CI again, there are no new issues.

However, I just got a bit confused with this error that started failing on master in the daily run from 3 days ago:

 failures:

---- tests::schema_with_keywords_works stdout ----
thread 'tests::schema_with_keywords_works' panicked at 'assertion failed: generated_code.contains(\"extern_\")', graphql_client_codegen/src/tests/mod.rs:32:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrac

Really looks like something that I could have caused with external_enum! But since master fails with the same error, it can't be my change. I can reproduce it locally when updating to nightly-2021-03-06 but it was fine before.

[tomhoule]

The tests look good! I think we can merge this, I sadly don't have time to invest in looking at what's wrong in CI now, but I definitely will when I have a few hours to spend on graphql-client. For now we can totally merge this, thanks a lot for the idea and the contribution!

[jakmeier]

Awesome, thanks for the swift responses and merging!