Defining a Mutation argument in graphql-yoga - node.js

Question

How do I create a Mutation with arguments for a resolver defined in graphql-yoga as:
const resolvers =
Mutation: {
createProject(root, args) {
const id = (Number(last(data.projects).id) + 1).toString()
const newProject = { ...args, id: id }
...
I've tried the following:
mutation CreateProject($name: String!) {
createProject {
data: {
name: $name
}
}
}
and
mutation CreateProject($name: String!) {
createProject($name: name) {
statusCode
}
}
which produces
and various other structures unsuccessfully.
There seems to be no reference to a Mutation in either the project README or any of the three examples.
Update
I'm now using:
mutation CreateProject($name: String!) {
createProject(name: $name) {
id
name
}
}
which is so similar to examples I've seen on the net that I feel it must be valid & the syntax is not rejected.
The schema definition is:
scalar ID
type Project {
id: ID
type: ProjectType
name: String
}
interface MutationResult {
statusCode: Int
message: String
}
type ProjectMutationResult implements MutationResult {
statusCode: Int
message: String
project: Project
}
type Mutation {
createProject: ProjectMutationResult
}
However on submitting the mutation, I receive:
{
"error": {
"errors": [
{
"message": "Unknown argument \"name\" on field \"createProject\" of type \"Mutation\".",
"locations": [
{
"line": 2,
"column": 17
}
]
},
{
"message": "Cannot query field \"id\" on type \"ProjectMutationResult\".",
"locations": [
{
"line": 3,
"column": 5
}
]
},
{
"message": "Cannot query field \"name\" on type \"ProjectMutationResult\".",
"locations": [
{
"line": 4,
"column": 5
}
]
}
]
}
}

Answer 1

According to your type definition:
The createProject mutation does not expect any argument:
type Mutation {
createProject: ProjectMutationResult
}
The ProjectMutationResult type does not have an id field nor a name field:
type ProjectMutationResult implements MutationResult {
statusCode: Int
message: String
project: Project
}
So when you run the mutation:
mutation CreateProject($name: String!) {
createProject(name: $name) {
id
name
}
}
you have a complete discrepancy between what you're feeding your GraphQL server and what it's actually expecting.
So first of all, if you want to be able to set a name to your project when you create it, you need to amend your createProject definition to this:
type Mutation {
createProject(name: String!): ProjectMutationResult
}
(if you want the naming to be optional, set name to be of type String rather than String!)
Then, assuming you want to retrieve the newly created project id and name from your mutation, change the mutation itself to:
mutation CreateProject($name: String!) {
createProject(name: $name) {
project {
id
name
}
}
}
You need to do this because your createProject mutation returns a ProjectMutationResult which itself contains a project field of type Project, which is the one defining the id and name fields.