GraphQL Mongoose: Cast to ObjectId failed for value - mongodb

Question

I have the following resolver for GraphQL:
const Post = require("../../models/Post");
module.exports = {
getAllActivePosts: async (userId) => {
try {
const posts = await Post.find({
userId: userId
})
.select(["name", "createdAt"])
.populate("posts", ["name", "createdAt"]);
return posts;
} catch (err) {
console.log(err);
throw err;
}
},
};
which tries to get all active posts by the ID of the user from the Post model:
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const PostSchema = new mongoose.Schema({
userId: {
type: Schema.Types.ObjectId,
ref: "User",
required: true,
},
content: {
type: String,
required: true,
},
createdAt: {
type: Date,
required: true,
}
});
module.exports = Post = mongoose.model("Post", PostSchema);
Here's the GraphQL Schema:
const { buildSchema } = require('graphql');
module.exports = buildSchema(`
type User {
_id: MongoId!
email: String!
password: String
}
type Post {
_id: MongoId!
userId: MongoId!
content: String!
createdAt: String!
}
scalar MongoId
input LoginInput {
email: String!
password: String!
}
type RootQuery {
login(email: String!, password: String!): AuthData!
getAllActivePosts(userId: MongoId!): [Post]
}
type RootMutation {
createUser(loginInput: LoginInput): AuthData!
}
schema {
query: RootQuery
mutation: RootMutation
}
`);
... and the GraphQL query I'm running in GraphiQL:
{
getAllActivePosts(userId: "5fbfc92312b90071179a160f") {
name
createdAt
}
}
For this, the result of the query is:
{
"errors": [
{
"message": "Cast to ObjectId failed for value \"{ userId: '5fbfc92312b90071179a160f' }\" at path \"userId\" for model \"Post\"",
"locations": [
{
"line": 2,
"column": 3
}
],
"path": [
"getAllActivePosts"
]
}
],
"data": {
"getAllActivePosts": null
}
}
Searched here for similar issues, tried wrapping userId in ObjectId, but nothing helped. What am I missing here?

Answer 1

I was go through this problem once a year ago with no solution till i get main concept of graphql.
Here you are passing string
{
getAllActivePosts(userId: "5fbfc92312b90071179a160f") {
name
createdAt
}
}
and graphql expecting to have mongoose.Types.ObjectId
getAllActivePosts(userId: MongoId!): [Post]
You need to do sync like
getAllActivePosts(userId: mongoose.Types.ObjectId("5fbfc92312b90071179a160f")) {
But using above way you are not eligible for run query in graphiQL becuse there is no mongoose defined.
type RootQuery {
login(email: String!, password: String!): AuthData!
getAllActivePosts(userId: String!): [Post]
}
Better solution is use userId input as string and then validate on your resolver function like
getAllActivePosts: async ({ userId }) => {
try {
if(mongoose.Types.ObjectId.isValid(userId)) {
const posts = await Post.find({
userId: userId
})
.select(["name", "createdAt"])
.populate("posts", ["name", "createdAt"]);
// you can;t return null you need to return array
return posts ? posts : []
} else {
// if mongoose id is wrong
return []
}
} catch(error) {
// it is better to throw error return blank array to complete flow
throw error
}
}

Answer 2

Turned out, I was using userId directly, whereas I should've used args.userId. The proper resolver below:
module.exports = {
getAllActivePosts: async (args) => {
try {
const posts = await Post.find({
userId: args.userId
})
.select(["name", "createdAt"])
.populate("posts", ["name", "createdAt"]);
return posts;
} catch (err) {
console.log(err);
throw err;
}
},
};
and for the schema:
getAllActivePosts(userId: String!): [Post]