I have a setup where I run a query on the frontend through the router (Apollo Federation Gateway) to two separate services exposing GQL endpoints - serviceA has findItems and serviceB has parseName.
Now I want to run the following query in one go:
query findMyItemDescriptionNameAndParse {
findItems(id: 1) {
description {
name
}
}
parseName(input: $name) {
parsedName {
name
}
}
}
Can Apollo pass the variables internally or I just have to split the query into two for such case?
Thank you.
Short answer: no. You'd have to run the two queries in sequence. What's preferable however is to define a different query that returns both the name and parsedName that you're looking for. Even better would be to extend the description to include a parsedName field and just write a resolver for that then you'd never need to run sequential queries.
Related
i'm learning to use apollo client and I saw that it used to contain "compose" method which combines multiple queries, so we can call two queries in a single request without explicitly write a whole new query.
lets say I have 2 queries
const getUsersQuery = gql`query getUsers ($name:String!){
users{
name
}
}`
const getPokemonsQuery = gql`query getPokemon($id:ID!){
pokemon (id:$id) {
name
}
}`
So a compose method will return an object which I can use to fetch these two queries in single request and include the variables for the two queries.
I didn't find a way to do it in the latest version.
I have a mutation:
const createSomethingMutation = gql`
mutation($data: SomethingCreateInput!) {
createSomething(data: $data) {
something {
id
name
}
}
}
`;
How do I create many Somethings in one request? Do I need to create a new Mutation on my GraphQL server like this:
mutation {
addManySomethings(data: [SomethingCreateInput]): [Something]
}
Or is there a way to use the one existing createSomethingMutation from Apollo Client multiple times with different arguments in one request?
You can in fact do this using aliases, and separate variables for each alias:
const createSomethingMutation = gql`
mutation($dataA: SomethingCreateInput!) {
createA: createSomething(data: $dataA) {
something {
id
name
}
}
createB: createSomething(data: $dataB) {
something {
id
name
}
}
}
`;
You can see more examples of aliases in the spec.
Then you just need to provide a variables object with two properties -- dataA and dataB. Things can get pretty messy if you need the number of mutations to be dynamic, though. Generally, in cases like this it's probably easier (and more efficient) to just expose a single mutation to handle creating/updating one or more instances of a model.
If you're trying to reduce the number of network requests from the client to server, you could also look into query batching.
It's not possible so easily.
Because the mutation has one consistent name and graphql will not allow to have the same operation multiple times in one query. So for this to work Apollo would have to map the mutations into aliases and then even map the variables data into some unknown iterable form, which i highly doubt it does.
How would you use graphQL to query by a "relational" entity value?
For instance, lets say we have a bunch of person-objects. Each "person" then has a relation to an interest/hobby which then has a property called "name".
Now lets say that we want to query for the name of each person with a specific interest, how would such a query be "conducted" using GraphQL?
Using OData it would be something like Persons?$select=name&$expand(Interests($filter=name eq 'Surfing')).. what would be the equivalent for GraphQL?
There is no one equivalent. With the exception of introspection, the GraphQL specification does not dictate what types a schema should have, what fields it should expose or what arguments those fields should take. In other words, there is no one way to query relationships or do things like filtering, sorting or pagination. If you use Relay, it has its own spec with a bit more guidance around things like pagination and connections between different nodes, but even Relay is agnostic to filtering. It's up to the individual service to decide how to implement these features.
As an example, if we set up a Graphcool or Prisma server, our query might look something like this:
query {
persons(where: {
interest: {
name: "Surfing"
}
}) {
name
}
}
A query to a Hasura server might look like this:
query {
persons(where: {
interest: {
name: {
_eq: "Surfing"
}
}
}) {
name
}
}
But there's nothing stopping you from creating a schema that would support a query like:
query {
persons(interest: "Surfing") {
name
}
}
It's possible to pass a query, but apparently not a fragment:
server.use('/graphiql', graphiqlExpress({
endpointURL: '/graphql',
query: `# Welcome to GraphiQL
query PostsForAuthor {
author(id: 1) {
firstName
posts {
title
votes
}
}
}`}));
Update 10/12/2017
It is possible to send fragments along with a query using Apollo's client:
http://dev.apollodata.com/core/fragments.html
This is not a solution to the original question, however; I would like to pass fragments to a graphiql server instance at startup.
by startup do you mean from the server? if so I don't believe that's how fragments are used. my understanding is as follows:
on the server you provide Types (like User)
on the client you query those Types using queries and fragments
for instance, if you provide type User on the server, on the client graphQL you can use fragments to query that type:
graphQL (client)
fragment authorData on AuthorType{
firstName
posts {
title
votes
}
}
query PostsForAuthor {
author(id: 1) {
...authorData
}
}
As you noticed (and as detailed here) GraphiQL takes a query argument:
query: an optional GraphQL string to use as the initial displayed query, if undefined is provided, the stored query or defaultQuery will be used.
If putting a fragment in as the value for that argument doesn't work, then I don't believe there is any way to start with a fragment ... but really why would you even want to? A fragment by itself isn't executable, and the whole idea is to start GraphiQL with a (executable) query.
If all you want is to be able to copy/paste in some text that you use frequently in your queries, a bookmarklet might be a better idea.
Graphql is great and I've started using it in my app. I have a page that displays summary information and I need graphql to return aggregate counts? Can this be done?
You would define a new GraphQL type that is an object that contains a list and a number. The number would be defined by a resolver function.
On your GraphQL server you can define the resolver function and as part of that, you would have to write the code that performs whatever calculations and queries are necessary to get the aggregate counts.
This is similar to how you would write an object serializer for a REST API or a custom REST API endpoint that runs whatever database queries are needed to calculate the aggregate counts.
GraphQL's strength is that it gives the frontend more power in determining what data specifically is returned. Some of what you write in GraphQL will be the same as what you would write for a REST API.
There's no automatic aggregate function in GraphQL itself.
You can add a field called summary, and in the resolve function calculate the totals.
You should define a Type of aggregated data in Graphql and a function you want to implement it. For example, if you want to write the following query:
SELECT age, sum(score) from student group by age;
You should define the data type that you want to return:
type StudentScoreByAge{
age: Int
sumOfScore: Float
}
and a Graphql function:
getStudentScoreByAge : [StudentScoreByAge]
async function(){
const res = await client.query("SELECT age, sum(score) as sumOfScore
from Student group by age");
return res.rows;
}
... need graphql to return aggregate counts? Can this be done?
Yes, it can be done.
Does GraphQL does it automatically for you? No, because it does not know / care about where you get your data source.
How? GraphQL does not dictate how you get / mutate the data that the user has queried. It's up to your implementation to get the requested aggregated data. You could get aggregated data directly from your MongoDB and serve it back, or you get all the data you need from your data source and do the aggregation yourself.
If you are using Hasura, in the explorer, you can definitely see an "agregate" table name, thus, your query would look something similar to the following:
query queryTable {
table_name {
field1
field2
}
table_name_aggregate {
aggregate { count }
}
}
In your results, you will see the total row count for the query
"table_name_aggregate": {
"aggregate": {
"count": 9973
}
This depends on whether you build the aggregator into your schema and are able to resolve the field.
Can you share what kind of GraphQL Server you're running? As different languages have different implementations, as well as different services (like Hasura, 8base, and Prisma).
Also, when you say "counts", I'm imagining a count of objects in a relation. Such as:
query {
user(id: "1") {
name
summaries {
count
}
}
}
// returns
{
"data": {
"user": {
"name": "Steve",
"summaries": {
"count": 10
}
}
}
}
8base provides the count aggregate by default on relational queries.