Issue in querying graphQL relay calls (.then is not a function) - graphql

Question

I have a graphql server running which I am using for query one of the object that gets instantiated when server starts (kind of in-memory db). Here company object is created every time schema is loaded or say server is started which I am using in QueryType object to resolve.
Here is the graphQL Schema
const {
GraphQLSchema,
GraphQLObjectType,
GraphQLString,
GraphQLInt,
GraphQLList
} = require('graphql');
const {
connectionDefinitions,
connectionArgs,
connectionFromArray,
connectionFromPromisedArray
} = require('graphql-relay');
//**************************** In-Memory Data ********************************//
var company = {
id:'123456',
customFieldDefinitions:[
{
name: 'cfm1',
id: '123'
},
{
name: 'cfm2',
id: '1234'
}
]
};
//**************************** In-Memory Code Ends *********************************//
const CustomFieldDefinitionType = new GraphQLObjectType({
name: 'Common_CustomFieldDefinitionsConnection',
fields: {
id: {
type: GraphQLString,
resolve: (cfd) => cfd.id
},
name: {
type: GraphQLString,
resolve: (cfd) => cfd.name
}
}
});
const { connectionType: CustomFieldDefinitionConnection } =
connectionDefinitions({
name: 'Common_CustomFieldDefinition',
nodeType: CustomFieldDefinitionType
});
const CompanyType = new GraphQLObjectType({
name: 'Company',
fields: {
id: {
type: GraphQLString,
resolve: (obj) => obj.id
},
customFieldDefinitions: {
type: CustomFieldDefinitionConnection,
description: 'A list of Custom Fields',
args: connectionArgs,
resolve: (obj, args) => connectionFromPromisedArray(obj.customFieldDefinitions, args)
}
}
});
const QueryType = new GraphQLObjectType({
name: 'Query',
fields: {
company: {
args: {
id: { type: GraphQLString },
},
type: CompanyType,
resolve: (_, args) => company
}
}
});
const mySchema = new GraphQLSchema({
query: QueryType
});
module.exports = mySchema;
Now when I try to query as below on graphiQL editor
query{
company{
customFieldDefinitions {
edges {
node {
id
}
}
}
}
}
I get error as below.
{
"data": {
"company": {
"customFieldDefinitions": null
}
},
"errors": [
{
"message": "dataPromise.then is not a function",
"locations": [
{
"line": 3,
"column": 5
}
],
"path": [
"company",
"customFieldDefinitions"
]
}
]
}
How can I identify the problem?

Answer 1

It looks like the error is with this line:
resolve: (obj, args) => connectionFromPromisedArray(obj.customFieldDefinitions, args)
The problem is that the connectionFromPromisedArray function imported from graphql-relay expects a promise that returns an array and obj.customFieldDefinitions is a normal array. Just to trace it back, obj is the parent element of that resolver which in this case is what you return from the company resolver on the Query type.
To fix it, either change connectionFromPromisedArray to connectionFromArray or change your company object to this:
var company = {
id:'123456',
customFieldDefinitions: Promise.resolve([
{
name: 'cfm1',
id: '123'
},
{
name: 'cfm2',
id: '1234'
}
])
};