Apollo Gateway 2.x broke Node resolver pattern

jukben · June 20, 2022, 11:05am

Hey, try this forum to get some help. The whole issue is described in this issue:

Apollo Gateway Query Plan incorrectly handles union/fragment of sharable Interfaces

opened 06:38PM - 16 Jun 22 UTC

I am running into a problem when running a query of a shared interface that is a…lso a field on `Query`. Essentially, it appears that something is causing confusion in the query plan where the query plan is defaulting to a particular subgraph. If that subgraph does not have the implementation of the type, it drops the union/fragment. We have built a plugin with logic that can analyze the `id` and point the query to the correct subgraph, and can get a return on the gateway, but when the gateway returns the the client, the result is `null`. I assume this is because the gateway is attempting to return a type belonging to the "default" subgraph instead of the correct subgraph and something is failing. I have seen some recent PRs that impact the query plan - was not sure if this may be related. - https://github.com/apollographql/federation/pull/1911 - https://github.com/apollographql/federation/pull/1859 Also entirely possible that I've misunderstood how to decorate these types/fields, so could be human error. Happy to provide more details, but didn't want to overwhelm with a wall of output. ### Reproducable example Subgraph 1 ``` extend schema @link(url: "https://specs.apollo.dev/federation/v2.0", import: ["@key", "@shareable"]) interface Node { id: ID! } type Query { node(id: ID!): Node @shareable } ``` Subgraph 2 ``` extend schema @link(url: "https://specs.apollo.dev/federation/v2.0", import: ["@key", "@shareable"]) interface Node { id: ID! } type Foobar implements Node { id: ID! uuid: String! version: Int! name: String! description: String category: [String!] } type Query { node(id: ID!): Node @shareable } ``` Supergraph (partial/relevant bits - I can share more if helpful) ``` enum join__Graph { SUBGRAPH1 @join__graph(name: "subgraph1", url: "https://path.com") SUBGRAPH2 @join__graph(name: "subgraph2", url: "https://otherpath.com") } interface Node @join__type(graph: SUBGRAPH1) @join__type(graph: SUBGRAPH2) { id: ID! } type Foobar implements Node @join__implements(graph: SUBGRAPH2, interface: "Node") @join__type(graph: SUBGRAPH2) { id: ID! uuid: String! version: Int! name: String! description: String category: [String!] } type Query @join__type(graph: SUBGRAPH1) @join__type(graph: SUBGRAPH2) { node(id: ID!): Node } ``` Query (from client) ``` query SampleQuery($id: ID!) { node(id: $id) { __typename id ... on Foobar { uuid } } } ``` QueryPlan (should be subgraph2) ``` QueryPlan { Fetch(service: "subgraph1") { { node(id: $id) { __typename id } } }, } ```

Let me know if you would like to pair-program or whatever!

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Apollo Gateway 2.x broke Node resolver pattern

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