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10-12-2020 08:40 PM
I have type definition for A
and B
defined in the schema.graphql
file. Resolvers for these are auto-generated and work well.
To create a scoring mechanism that ranks nodes with label B in relation to the node with label A, I am writing a CustomResolver
query that executes a cypher query and returns a collection of bs and a computed score as defined in the ScoredBs
type.
The schema.graphql
file looks like this.
type Query {
CustomResolver(idA: ID!, idsB: [ID!]!): [ScoredBs]
}
type A {
id: ID! @id
# and some more stuff of course
}
type B {
id: ID! @id
# more fields that use the @relation or @cypher decorator
}
type ScoredBs {
bs: [B]
score: Float
}
This is where the custom resolver is defined:
const resolvers = {
Query: {
CustomResolver: async (
parent,
{ idA, idsB },
context,
info
) => {
const cypher = `
MATCH (a:A {id: $idA})
MATCH (a)<--(b:B) WHERE b.id IN $idsB
WITH
b
RETURN DISTINCT collect(b) AS bs, rand() AS score
ORDER BY score DESC
`
const session = context.driver.session()
const results = await session
.run(cypher, { idA, idsB })
.then((result) => {
return result.records.map((record) => {
return {
bs: record.get('bs'),
score: record.get('score')?.low || null,
}
})
})
.catch(console.log)
.then((results) => {
session.close()
return results
})
return results
},
},
}
When I run the query in the apollo-server graphql playground i am receiving an error:
"message": "Resolve function for "B.id" returned undefined",
query {
CustomResolver(
idA:"2560886f-654b-4047-8d7a-386cd7d9f670",
idsB: ["01ec8367-a8ae-4600-9f88-ec141b2cae2c", "032f9a88-98c3-4968-8388-659ae26d63b3"]
) {
bs {
id
}
score
}
}
10-12-2020 10:53 PM
I solved this by rewriting part of the code:
const results = await session
.run(cypher, { idA, idsB })
.then((result) => {
return result.records.map((record) => {
// diff start
const obj = record.toObject()
const bs = obj.bs.map((b) => b.properties)
return {
bs, // diff end
score: record.get('score')?.low || null,
}
})
})
.catch(console.log)
.then((results) => {
session.close()
console.log(results)
return results
})
return results
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