Federation entity union is empty during schema introspection

[ggrise]

Expected Behavior

union _Entity = ... list of entities..

Actual Behavior

union _Entity = empty

Steps to Reproduce the Problem

Create a federated entity and do a schema introspection, union _Entity remain empty.

I believe the bug was introduced in v2.10.3

Specifications

• Version: v2.10.3
• Platform:
• Subsystem:

[sunli829]

Can you give an example to reproduce this problem? 🙂

[ggrise]

Yes, sorry for not giving more details:

If we run /async-graphql/examples/federation/federation-reviews and execute an introspection query on it

query IntrospectionQuery { __schema { types { name,kind,possibleTypes { name }  }}}

We should expect:

{
  "kind": "UNION",
  "name": "_Entity",
  "possibleTypes": [
    {
      "name": "Product"
    },
    {
      "name": "User"
    }
  ]
},

But we get the following instead

{
  "kind": "UNION",
  "name": "_Entity",
  "possibleTypes": []
},

thanks!

[sunli829]

Because this service itself does not contain any entities.

You should do it like this:

https://github.com/async-graphql/examples/blob/8641a72c8ccb78e924e2550cd1fbfa2e62319174/federation/README.md

[ggrise]

You can repeat it with federation-products example:

full details:

Run the federation product service (no need for a gateway)

$ cd examples/federation/federation-products
$ cargo run 

Curl the service directly with an introspection query:

$ curl 'http://localhost:4002/graphql' --data-raw '{"operationName":"IntrospectionQuery","variables":{},"query":"query IntrospectionQuery { __schema { types { name,kind,possibleTypes { name }  }}}"}' |  jq  '.data.__schema.types[]|select(.name == "_Entity")'
{
  "name": "_Entity",
  "kind": "UNION",
  "possibleTypes": []
}

Notice the possibleTypes should be set to Product since it's a federated entity in federation-products

Since the bug was introduced in v2.10.3, if you checkout v2.10.2 and run federation-products again:

$ git checkout v2.10.2
$ cd examples/federation-products
$ cargo run

You get the correct answer for possibleTypes

$ curl 'http://localhost:4002/graphql' --data-raw '{"operationName":"IntrospectionQuery","variables":{},"query":"query IntrospectionQuery { __schema { types { name,kind,possibleTypes { name }  }}}"}' |  jq  '.data.__schema.types[]|select(.name == "_Entity")'
{
  "kind": "UNION",
  "name": "_Entity",
  "possibleTypes": [
    {
      "name": "Product"
    }
  ]
}

I believe the bug was introduced here:

async-graphql/src/model/type.rs

Line 146 in 4793c36

} else if let TypeDetail::Named(registry::MetaType::Union { union_values, .. }) =

union_values is used to list the possibleTypes, but unfortunately, we don't add the types into union_values when we defined _Entity.

async-graphql/src/registry/mod.rs

Line 506 in 0f1e5a1

union_values: Default::default(),

I can make a PR if you like.

[Miaxos]

Oops, it seems I forgot something, it's my commit: a3b7777

[sunli829]

I'm working on it.

[sunli829]

Fixed in 3.0