GraphQL union and conflicting types

Question

I have a problem with my project and I can not find any solution on the Internet. Here is the situation.

• I have a Union ( DataResult ) of 2 types ( Teaser and Program )
• I have a Zone type with data field (array DataResult )
• Teaser & Program have the same title field with a different type ( String and String! )

Here are parts of the Zone , Teaser and Program diagrams:

 type Program { title: String } type Teaser { title: String! } union DataResult = Teaser | Program type Zone { (...) data: [DataResult!] } 

When I tried to query the zone data as described in the part of the query below, I had an error in GraphQL.

 zones { ...zoneFieldsWithoutData data { ... on Program { ...programFields } ... on Teaser { ...teaserFields } } } 

Here is the error:

 Error: GraphQL error: Fields \"title\" conflict because they return conflicting types String and String!. Use different aliases on the fields to fetch both if this was intentional 

I cannot use an alias because the specs need the same attribute name for all DataResult objects. What can I do?

Moreover, even if I set the same type for title , I will get many warnings about "missing fields" in the console ....

PS: I use Vanilla Apollo as a GraphQL client (server side)

Answer 1

Implemented according to the specification: See 3.a at: http://facebook.imtqy.com/graphql/draft/#SameResponseShape ()

See https://github.com/graphql/graphql-js/issues/1361#issuecomment-393489320 for more details.

Answer 2

Using the interface solved this problem for me, including the “missing field” - errors (although this means that the fields should be of the same type, I think).

Sort of

 interface DataResult { title: String! } type Program implements DataResult { // Not sure if this can be empty? } type Teaser implements DataResult { // Not sure if this can be empty? } type Zone { (...) data: [DataResult!] }