Mongoose .populate() not working correctly

I'm trying to create a Tumblr clone with GraphQL and MERN. Right now I'm just trying to create the template for posts with photos.

Just in case it's relevant, I am doing regular REST post requests with axios and express for the image files. I take the response from those, map over the _ids and send them in the createPost mutation.

In graphiql I can query for a single Image model and get everything back fine, like so:

{    image(_id: "someId"){      _id      url     created    }  }  

But when I do a subquery with the ObjectIds I've pushed into the Post arrays I get null for everything besides _id and __typename:

{    post(_id: "someId"){      _id      mainImages {       _id   //returns value       url  //returns null       created   //returns null       __typename   //returns value     }    }  }  

The posts have two arrays of objects with ObjectId and ref for images, the Post model:

const mongoose = require('mongoose');  const Schema = mongoose.Schema;    const PostSchema = new Schema({    mainImages: [      {        type: Schema.Types.ObjectId,        ref: 'Image'      }    ],    bodyImages: [      {        type: Schema.Types.ObjectId,        ref: 'Image'      }    ],  })    module.exports = mongoose.model('Post', PostSchema, 'posts')    

The Image model:

const mongoose = require('mongoose');  const Schema = mongoose.Schema;    const ImageSchema = new Schema({    url: {      type: String,      required: true    },    created: {      type: Date,      required: true    }  })    module.exports = Image = mongoose.model('Image', ImageSchema, 'images');  

The PostType:

const PostType = new GraphQLObjectType({    name: 'PostType',    fields: () => ({      _id: { type: GraphQLID },      mainImages: {         type: new GraphQLList(ImageType),        resolve(parentValue) {          return Post.findById(parentValue._id)            .populate('images')            .then(post => post.mainImages)        }      },      bodyImages: {        type: new GraphQLList(ImageType),        resolve(parentValue) {          return Post.findById(parentValue._id)            .populate('images')            .then(post => post.bodyImages)        }      },    })  })    module.exports = PostType;  

I'm wondering if .populate('images') isn't working correctly. I thought that if you have the ObjectIds then .populate() can take care of the rest. I've been looking around at a bunch of different questions but none of them have seemed to be relevant enough to my situation, and the GraphQL and Mongoose docs also haven't given me a breakthrough yet.

https://stackoverflow.com/questions/66684060/mongoose-populate-not-working-correctly March 18, 2021 at 10:47AM