How to share field definitions between inputObjectType and objectType definitions?

[carnesen]

For example, suppose I'm trying to implement the following as a Nexus schema:

input MessageInput {
  content: String
  author: String
}
 
type Message {
  id: ID!
  content: String
  author: String
}

Right now I'm defining the common fields content and author both explicitly in the inputObjectType and objectType definition blocks. Is there a way in Nexus to pull out the common field definitions?

Thanks in advance,
Chris

[shreyas44]

Hey @carnesen! I don't think there's a built in way to achieve what you're talking about. However, you could try using the below workaround. I haven't tested it, so I'm not sure if it would work or not.

const messageDefinition = (t) => {
  t.string("content")
  t.string("author")
}

const MessageInput = inputObjectType({
  name: "MessageInput",
  defintion: messageDefinition,
})

const Message = objectType({
  name: "Message",
  defintion(t) {
    t.id("id")
    messageDefinition(t)
  }
})

[carnesen]

Thank you for the reply! Is there a TypeScript type we can use for t in messageDefinition?

[NEO97online]

It looks like this is pretty difficult to type without just using t: any. I wonder if we could make this easier to type?

[rozsival]

@auderer @carnesen You can make use of generics for that case:

import {
  InputDefinitionBlock,
  OutputDefinitionBlock,
} from 'nexus/dist/definitions/definitionBlocks'

const messageDefinition = <N extends string>(t: InputDefinitionBlock<N> | OutputDefinitionBlock<N>) => {
  t.string('content')
  t.string('author')
}

It's not an ideal solution but it works in most cases. I wish there was some kind of shared interface which defines methods that are usable on both inputs and outputs.

[RubenMoraVargas]

@rozsival very good idea, maybe can improve defining a generic type :
type DefinitionBlock<N extends string> = InputDefinitionBlock<N> | OutputDefinitionBlock<N>;
export const wordDefinition = <N extends string>(t: DefinitionBlock<N>) => { ...

[Frosty21]

how could you extend it to a field in generics?