Is it possible to add another field in the final response of GraphQL query? - graphql

Question

I've been trying to research on how to add another root property of a GraphQL response but found nothing after 1 hour.
Normally, a GraphQL query looks like this:
{
myQuery() {
name
}
}
It responds with:
{
"data": {
"myQuery": []
}
}
I'm curious if I can add another root property in this response say "meta"
{
"data": {
"myQuery": []
},
"meta": {
"page": 1,
"count": 10,
"totalItems": 90
}
}
Is this possible, if not what's the best approach in tackling this with respect to GraphQL?
Thanks!

Answer 1

The apollo-server middleware can be configured with a number of configuration options, including a formatResponse function that allows you to modify the outgoing GraphQL response
const formatResponse = (response) => {
return {
meta
...response
}
}
app.use('/graphql', bodyParser.json(), graphqlExpress({
schema,
formatResponse,
}));
You could pass the req object down to your context, mutate it within your resolver(s) and then use the result inside formatResponse. Something like...
app.use('/graphql', bodyParser.json(), (req, res, next) => graphqlExpress({
schema,
formatResponse: (gqlResponse) => ({
...gqlResponse
meta: req.metadata
}),
})(req, res, next));
Typically, though, you would want to include the metadata as part of your actual schema and have it included with the data. That will also allow you to potentially request multiple queries and get the metadata for all of them.
There's any number of ways to do that, depending on how your data is structured, but here's an example:
type Query {
getFoos: QueryResponse
getBars: QueryResponse
}
type QueryResponse {
results: [Result]
meta: MetaData
}
union Result = Bar | Foo

Answer 2

You can add anything in the response as well... Please follow below code.
app.use('/graphql', bodyParser.json(), graphqlExpress(req => {
return {
schema: tpSchemaNew,
context: {
dbModel
},
formatError: err => {
if (err.originalError && err.originalError.error_message) {
err.message = err.originalError.error_message;
}
return err;
},
formatResponse : res => {
res['meta'] = 'Hey';
return res;
}
}
}))

Answer 3

Apollo Server-specific:
Just adding to the previous answers that formatResponse() has another useful argument, requestContext.
If you are interested in extracting values from that (for example, the context passed to the resolver), you can do the following. BEWARE HOWEVER, the context will likely contain sensitive data that is supposed to be private. You may be leaking authentication data and secrets if not careful.
const server = new ApolloServer({
schema,
formatResponse: (response, requestContext) => {
//return response
const userId = requestContext.context.user.id
response = Object.assign(response, {
extensions: {
meta: {
userId: userId
}
}
}
return response
},
})
The above will return something like this in the gql query response (note the extensions object):
{
data: {
user: {
firstName: 'Hello',
lastName: 'World'
}
},
extensions: { // <= in Typescript, there is no `meta` in GraphQLResponse, but you can use extensions
meta: {
userId: 1234 //<= data from the context
}
}
}
The full list of properties available in requestContext:
at node_modules/apollo-server-types/src/index.ts>GraphQLRequestContext
export interface GraphQLRequestContext<TContext = Record<string, any>> {
readonly request: GraphQLRequest;
readonly response?: GraphQLResponse;
readonly context: TContext;
readonly cache: KeyValueCache;
// This will be replaced with the `operationID`.
readonly queryHash?: string;
readonly document?: DocumentNode;
readonly source?: string;
// `operationName` is set based on the operation AST, so it is defined even if
// no `request.operationName` was passed in. It will be set to `null` for an
// anonymous operation, or if `requestName.operationName` was passed in but
// doesn't resolve to an operation in the document.
readonly operationName?: string | null;
readonly operation?: OperationDefinitionNode;
/**
* Unformatted errors which have occurred during the request. Note that these
* are present earlier in the request pipeline and differ from **formatted**
* errors which are the result of running the user-configurable `formatError`
* transformation function over specific errors.
*/
readonly errors?: ReadonlyArray<GraphQLError>;
readonly metrics?: GraphQLRequestMetrics;
debug?: boolean;
}