Response from GraphQL Mutation not working as expected - neo4j

Question

I am running a GraphQl mutation via a resolver. Its against a Neo4j database. The query is working fine but I am not able to structure the results in a way that they are displayed back in the result. I've tried several different combinations of results and record mapping but I can't get the properties of the returned result set to show in the outputs.
Specifically, you will see in the below examples that the name field in the response (via GraphiQL) is null when I expect it to be set to the value returned.
Resolver:
AddIdiomHasChildIdiom(object, params, ctx, resolveInfo) {
//************************************************************************************************************************************
//** Author: MOS
//** Date: 22/07/2019
//** Description: Add a child Idiom
//************************************************************************************************************************************
//Build the cypher query across multiple lines so that we can adjust the query depending on which parameters are passed
let query = new StringBuilder();
query.appendLine("MATCH (p:entity:Idiom {id:'" + params.from.id + "'}), (c:entity:Idiom {id:'" + params.to.id + "'})")
query.appendLine("MERGE (p)-[r:HAS_CHILD_IDIOM]->(c)")
query.appendLine("RETURN p,c")
console.log(query)
//Execute the query and send the results back to the user
return ctx.driver.session().run(query.toString(), {props:params})
.then(result => {
return {
from: result.records.map(record => { return record.get("p").properties}),
to: result.records.map(record => { return record.get("c").properties})
}
})
.catch(error => {
//ToDo: Error handling code need to go here
})
}
GraphQL Query
mutation{
AddIdiomHasChildIdiom(from:{id:"d94676b0-ac6c-11e9-a7a1-edf120d553ac"},to:{id:"e730a720-ac74-11e9-a45f-df629a6df5e1"})
{
from{
name
}
to{
name
}
}
}
Output:
{
"data": {
"AddIdiomHasChildIdiom": {
"from": {
"name": null
},
"to": {
"name": null
}
}
}
}
Relevant Schema Parts
type Mutation{
AddIdiomHasChildIdiom(
from: _IdiomInput!
to: _IdiomInput!
): _AddIdiomHasChildIdiomPayload
}
type _AddIdiomHasChildIdiomPayload {
from: Idiom
to: Idiom
}
input _IdiomInput {
id: ID!
}
type _AddIdiomHasChildIdiomPayload {
from: Idiom
to: Idiom
}
type Idiom {
id: ID
name: String
type: IdiomType
description: String
lifecycle: IdiomLifecycle
quality: Float
numStates: Int
numChildIdioms: Int
hasChildIdiom: [Idiom]
first: Int
offset: Int
orderBy: [_IdiomOrdering]
}

Answer 1

The problem in your code isthat you have mistmatch type between your graphql schema and the implementation of your resolver.
Your mutation query should return this :
type _AddIdiomHasChildIdiomPayload {
from: Idiom
to: Idiom
}
And your resolver returns this :
return {
from: result.records.map(record => { return record.get("p").properties}),
to: result.records.map(record => { return record.get("c").properties})
}
Here you are using a map function, and its result is an array.
So you are returning something like that :
{
from : [ { id:'', name:'', ... } ]
to : [ { id:'', name:'', ... } ]
}
And [ { id:'', name:'', ... } ] doesn't validate the Idiom type of your schema, it's an array : Idiom[].
So you need to change your resolver to return just one element for from & to.
And moreover, your implementation is weird : you are doing two loop against the result of Neo4j, due to the use of two map and you don't close the session.
You should try something like that :
const session = ctx.driver.session();
return session.run(query.toString(), {props:params})
.then(result => {
return result.records.map(record => {
return {
from:record.get("p").properties
to:record.get("c").properties
}
})[0]
})
.catch(error => {
//ToDo: Error handling code need to go here
})
.finally(() => {
session.close();
})
Moreover