I've a graphql-jave v8.0 app running on Spring boot v1.5.10, and I'm trying to utilize 'fragment' feature of GraphQL to fetch limited number of fields with the following schema type definition:
type School {
id: ID
name: String
address: String
age: String
jobTitle: String
...
}
fragment UserFields on School {
age
jobTitle
}
type Query {
user (id: String!): School!
}
schema {
query: Query
}
When I execute this query:
{
user (id: "123")
{
... UserFields
}
}
The expected result should be:
{
"user": {
"age": "12",
"jobTitle": "student"
}
}
However, It results in the following error
"message": "Validation error of type UndefinedFragment: Undefined fragment
UserFields # 'user'",
Off course I can do this with explicitly passing the field name in the query but for the sake of example, I'm interested in utilizing fragment feature of GraphQL.
Any idea what I'm doing wrong please?
Fragments aren't defined in the schema, they're something for letting you create abstractions whilst building complex queries -- the main purpose is to allow you to avoid repetition when querying the same type in multiple parts of your query.
As Andrew said, and as the official docs exemplify, fragments are not defined in the schema but (ad hoc) in the query:
{
user (id: "123") {
... UserFields
}
}
fragment UserFields on School {
age
jobTitle
}
Unconditional fragments (like the one here) are used to avoid repetition. Imagine having multiple places where you want to select age and jobTitle in the same operation.
Conditional fragments, on the other hand, are used to make a conditional selection depending on the concrete interface implementation or union subtype.
Related
Is this possible to specify more than one type of query in one schema?
type Query {
productsByRegion(match : String) : [Product]
productsByType(match : String) : [Product]
}
type Product {
id: ID
name: String
}
Expected queries which can be fired using single schema definition:
{
productsByRegion {
id
name
}
}
{
productsByType {
id
name
}
}
GraphQL java implementation cached some data. After server, restart both the query works fine.
Simple table with one two rows. ID (incrementing int) and test_value (TEXT, nullable).
1. Query
query getData($test_value:String!) {
testtable(where: {test_value: {_eq: $test_value}}) {
test_value
}
}
Variables
{"test_value":null}
Result
{
"errors": [
{
"extensions": {
"path": "$.selectionSet.testtable.args.where.test_value._eq",
"code": "validation-failed"
},
"message": "unexpected null value for type \"String\""
}
]
}
This is a correct that I expect.
2. Mutation
mutation InsertData($test_value: String!) {
insert_testtable(objects: {test_value: $test_value}) {
affected_rows
}
}
Variables
{"test_value":null}
Result
{
data: {
insert_testtable: {
affected_rows: 1
}
}
}
I expect and error (because of test_value:String! declaration), but I don't get it.
Why?
P.S.
testable schema looks like this:
id: Int!
test_value: String
My understanding of your issue: Your schema has a mutation insert_testtable that takes a nullable String argument. When you submit a named mutation operation with a non-nullable String! variable, the GraphQL server does not respond with an error.
The GraphQL spec says that is the expected behaviour for mutations and queries. The spec says that if the type in the schema is nullable and of the same type as the variable, the operation is to be considered valid. This is what's happening for your mutation.
If you are not seeing the same behaviour for the query, it is possible that your GraphQL server implementation differs from the spec. You could check your server docs or their GitHub Issues.
For what it's worth, I checked that AppSync, AWS's GraphQL implementation, produces the expected behaviour for both queries and mutations.
I'm using AWS AppSync's GraphQL server with the following (simplified) schema:
type Query {
getIssue(id: String!): Issue
}
type Issue {
id: String!
data: IssueData!
}
type Event {
id: String!
time: AWSDateTime!
status: [String]
}
type Payment {
id: String!
amount: Int!
status: String
}
union IssueData = Event | Payment
When I make a query that includes inline fragments to select the status as a child of either an Event or Payment type in the Issue/data field, I get a FieldsConflict error:
query getIssue($id: String!) {
getIssue(id: $id) {
id
data {
... on Event {
time
status
}
... on Payment {
amount
status
}
}
}
}
Validation error of type FieldsConflict: status: fields have different list shapes # 'getIssue/data'
This is presumably caused by the Event/status field returning an array of strings, while the Payment/status field returns a single string.
Why does GraphQL consider this to be a conflict? How should I construct my query to allow access to the status field on both data types?
Note that I'm using a union rather than an extended interface because the Issue and Payment types have no common data structure.
From the spec:
If multiple field selections with the same response names are encountered during execution, the field and arguments to execute and the resulting value should be unambiguous. Therefore any two field selections which might both be encountered for the same object are only valid if they are equivalent.
You can resolve the issue by providing a field alias for one or both fields:
query getIssue($id: String!) {
getIssue(id: $id) {
id
data {
... on Event {
time
eventStatus: status
}
... on Payment {
amount
status
}
}
}
}
Renaming one or both fields in your schema would obviously also resolve the issue.
I am trying to execute a mutation like so
mutation creating {
createTeam(
payload: {
name: "Team von abc"
tacts:["94b4cbc2-b996-482f-b712-967bdb646e73"]
}
) {
id
name
}
}
This results in :
"message": "Cannot perform update query because update values are not
defined. Call \"qb.set(...)\" method to specify updated values.",
My graphql is defined like this:
input CreateTeamPayload {
name: String
tacts:[ID!]
}
type Team {
id: ID!
name: String
tacts: [Tact]!
}
type Query {
fetchTeams: [Team]!
fetchTeamById(id: ID!): Team
}
type Mutation {
createTeam(payload: CreateTeamPayload): Team!
}
My Team requires an ID from a "tact" so I provide him with an ID from a "tact" I created before. Is this approach wrong? How can I mutate types that reference other types? is there some documentation that actually does this?
I'm trying to have a representation of nodes on GraphQL more akin to what jsonapi would be like http://jsonapi.org/
What I mean is if we take one of the examples on GraphQL
{
hero {
name
# Queries can have comments!
friends {
name
}
}
}
Have a representation that would be more along these lines
{
hero {
name
# Queries can have comments!
friends {
id
}
},
friends {
id, name
}
}
Is that at all possible in GraphQL
Thanks
It is possible, and there's nothing wrong with having a friends field. In GraphQL terms you can have the following part of the schema:
type User {
id: ID
name: String
firends: [User]
}
type RootQuery {
hero: User
friends(forUserId: ID!): [User]
}
And then you can query this as you like – you can ask for friends separately:
{
friends(forUserId: "12") {
id, name
}
}
But the whole idea of GraphQL is that you don't have to do multiple queries to get the information you need. If you just need a list of users – that's a reasonable query, that most people have (with arguments for pagination and so on). With that said, there's no reason to fetch a list of IDs and to send another fetch query for the data right after that.