Return selected fields only React Native / GraphQL / Amplify - react-native

Question

I have the following basic list query in GraphQL:
API.graphql(graphqlOperation(listSomething,{filter: filter})).then(({ data: { something } }) => {
// Returns the entire object
})
This will return an array containing entire objects, but as I've seen on multiple GraphQL tutorials, I'd like to take advantage of the utility of only returning / plucking select fields for obvious reasons. However there isn't a lot of information out there on GraphQL + RN + Amplify. So how would I re-write this query to only return the attribute id for instance? Or is that something that I have to define as a resolver in the graphql / queries.js file? I'm using autogenerated queries so it sort of feels like an anti-pattern to add your own queries to that file — Correct me if I'm wrong.
Thanks!

Answer 1

I'm still at an early stage of getting familiar with AWS, so please take this with a grain of salt.
Your auto generated queries.js will contain a listSomething query, that looks something like this:
export const listTodos = /* GraphQL */ `
query ListTodos(
$filter: ModelTodoFilterInput
$limit: Int
$nextToken: String
) {
listTodos(filter: $filter, limit: $limit, nextToken: $nextToken) {
items {
id
userID
name
description
createdAt
updatedAt
}
nextToken
}
}
`;
I created a new folder called /src/customGraphQL and created a file called customListTodos.js. I copied there the auto generated query, changed the query name, and removed the fields I didn't need.
export const customListTodos = /* GraphQL */ `
query CustomListTodos(
$filter: ModelTodoFilterInput
$limit: Int
$nextToken: String
) {
listTodos(filter: $filter, limit: $limit, nextToken: $nextToken) {
items {
name
description
}
nextToken
}
}
`;
I only changed the query's name, but kept the inner function's name as listTodos, so I'm running a customised version of that query. If the original API is pushed to AWS, you can import and use the custom query:
import {customListTodos} from './src/customGraphQL/customListTodos';
...
API.graphql(graphqlOperation(customListTodos ...

Answer 2

This worked for me. Making a custom queries file was pretty simple and I was able to limit the object to just returning the _version.
export const getUserVersion = /* GraphQL */ `
query GetUserVersion($id: ID!) {
getUser(id: $id) {
_version
}
}
`;
Then in my .js file I could call the function this way:
const getUserVersionResponse = await API.graphql(
graphqlOperation(getUserVersion, { id })
);