[Bug]: GraphQL fields listed after a fragment spread are silently dropped #3861

Note: The below was written and discovered by claude but I have independently verified it myself as well.

What happened?

When a selection set contains a fragment spread (or inline fragment), every field listed after it in the same selection set is never added to the SQL query. Those fields come back null with no error. This applies to both scalar fields and relationship fields.

Repro:

query {
  book_by_pk(id: 1) {
    ...bookFields
    title
    publishers { name }
  }
}

fragment bookFields on book { id }

Expected: id, title and publishers are populated.
Actual: id is populated; title and publishers are null.

The same query works if ...bookFields is moved to the end of the selection set, or removed.

Cause: in SqlQueryStructure.AddGraphQLFields, both the FragmentSpread and the InlineFragment branches recurse into the fragment and then return;. That exits the foreach over the remaining selections. These look like they should be continue;:

https://github.com/Azure/data-api-builder/blob/main/src/Core/Resolvers/Sql%20Query%20Structures/SqlQueryStructure.cs (the two return; statements after the recursive AddGraphQLFields calls)

The return; dates from #1236, which added fragment support for #1235. The Cosmos path (GenerateQueryColumns) iterates over every selection and isn't affected.

Version

2.1.5

What database are you using?

Azure SQL

What hosting model are you using?

Container Apps

Which API approach are you accessing DAB through?

GraphQL

Relevant log output

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