I am trying to use GraphQL with mysql in a node js express server.
but I am getting this error everytime I run my query
here is the error:
{
"errors": [
{
"message": "Expected Iterable, but did not find one for field \"RootQueryType.getAllGoals\".",
"locations": [
{
"line": 2,
"column": 3
}
],
"path": [
"getAllGoals"
]
}
],
"data": {
"getAllGoals": null
}
}
here is my Graphql Query:
query {
getAllGoals {
title
progress
goal
}
}
I get the result expected from "SELECT * FROM (my table)", but it gives me an error when I try to return it for GraphQL from the resolver as shown in the code below:
const RootQuery = new GraphQLObjectType({
name: "RootQueryType",
fields: {
getAllGoals: {
type: new GraphQLList(GoalType),
resolve(parent, args) {
return db.query("SELECT * FROM myTable", (err, result) => {
if (err) throw err
console.log(JSON.parse(JSON.stringify(result)))
return JSON.parse(JSON.stringify(result))
})
}
}
}
})
I have checked to see if I have any conflicts in my GraphQLObjectType GoalType, but I had none.
I have fixed it, I just needed to make a promise that included the query (as shown below):
async resolve(parent, args) {
var p = new Promise((resolve, reject) => {
db.query("SELECT * FROM myTable", (err, result) => {
console.log(JSON.parse(JSON.stringify(result)))
resolve(JSON.parse(JSON.stringify(result)))
})
})
return p
}
Your resolve method returns whatever db.query returns, but this is not what GraphQL expects: It expects the result of the query, or a promise that resolves to this result. You can use util.promisify to obtain such a promise.
If you also want to log the result, use a .then method as shown here:
resolve(parent, args) {
return util.promisify(db.query)("SELECT * FROM myTable")
.then(result => {
console.log(result);
return result;
});
}
(What's the purpose of JSON.parse(JSON.stringify(...))?)