How to expose graphql field with different name

Solution 1:

You can use GraphQL Aliases to modify individual keys in the JSON response.

If this is your original query

query {
  POJO {
    id
    name
  }
}

you can introduce a GraphQL alias userName for the field name like so:

query {
  POJO {
    id
    userName: name
  }
}

You can also use GraphQL aliases to use the same query or mutation field multiple times in the same GraphQL operation. This get's especially interesting when using field parameters:

query {
  first: POJO(first: 1) {
    id
    name
  }

  second: POJO(first: 1, skip: 1) {
    id
    name
  }
}

Solution 2:

The question is: how are you creating the schema in the first place? There's no intrinsic connection between Java and GraphQL types - they are completely unrelated unless you correlate them. So you can name the fields any way you want in the schema, and make a resolver (DataFetcher) that gets the value from anywhere (thus any POJO field too).

If you're using a tool to generate the schema from Java types (graphql-java-annotations, graphql-spqr etc), then use that tool's facilities to drive the mapping. Both the mentioned tools allow customizing the mapping via annotations. GraphQL-SPQR enables the same via external configuration as well.

If you clarify your question further, I'll be able to give a more precise answer.