graphql - combining results from multiple queries into one array - graphql

Question

I am using graphQL to perform a search across multiple mongoDB collections and API's by combining queries. All queries return a result type of
{
_id: string;
name: string;
type: string;
}
Is there any way to flatten the data into a single array?
Combined query example:
query searchAll {
books(input: {text: "e"}) {
_id
name
type
}
magazines(input: {text: "e"}) {
_id
name
type
}
}
Response currently looks like:
{"data": {
"books": [
{
"_id": "5a8ac759c25b7235ffdc6888",
"name": "someBook",
"type": "book"
}
],
"magazines": [
{
"_id": "5a87005bc25b7235ffdc4bdf",
"name": "someMagazine-1",
"type": "magazine"
},
{
"_id": "5a870067c25b7235ffdc4be4",
"name": "someMagazine-2",
"type": "client"
}
]
}
}
Desired response:
{"data": {
"results": [
{
"_id": "5a8ac759c25b7235ffdc6888",
"name": "someBook",
"type": "book"
},
{
"_id": "5a87005bc25b7235ffdc4bdf",
"name": "someMagazine-1",
"type": "magazine"
},
{
"_id": "5a870067c25b7235ffdc4be4",
"name": "someMagazine-2",
"type": "client"
}
]
}
}

Answer 1

You want to look into using interfaces, here's an example of a (slightly richer) schema definition:
interface Searchable {
id: ID!
name: String!
}
type Book implements Searchable {
id: ID!
name: String!
author: Author!
publisher: Publisher!
isbn: String!
}
type Magazine implements Searchable {
id: ID!
name: String!
publisher: Publisher!
issn: String!
}
input SearchInput {
text: String!
}
type Query {
search(input: SearchInput!): [Searchable!]!
}
Here's how you'd query it:
query searchAll {
search(input: {text: "e"}) {
__typename
id
name
... on Book {
author
isbn
}
... on Magazine {
issn
}
}
}
The resolver for search would be responsible for calling all the different collections and aggregating the results into a single array. Going into more depth than this is implementation-specific, but there should be docs for using interfaces (and unions, which are similar) in whichever GraphQL implementation you're using.
The __typename field is what tells you the concrete type of the returned object, thereby letting front-end code do the appropriate display logic.