Why am I getting a StrictPopulateError when trying to populate a path from an array in my Mongoose schema?

Question

how can I populate 'from and to' from messages array in this schema ?

const chatSchema = new Schema({
    POne: {type: Types.ObjectId, ref:'User', required: true},
    PTwo: {type: Types.ObjectId, ref:'User', required: true},
    messages:[{
      from:{type: Types.ObjectId, ref:'User', required: true},
      to:{type: Types.ObjectId, ref:'User', required: true},
      message: {type: String, required:true},
      date: {type: Date, default: Date.now}
    }]
}, {
    timestamps: true,
    toJSON: { virtuals: true }, 
    toObject: { virtuals: true },
})

this the end point I used

const chat = await chatModel.findOne({
        $or: [
            {POne: req.user._id, PTwo: destId},
            {POne: destId, PTwo: req.user._id},
        ]
    }).populate([{
        path:"POne"
    },{
        path: "PTwo"
    },{
        path:"from", options: {strictPopulate: false}
    },{
        path: "to", options: {strictPopulate: false}
    }]) 

even I did it turning off strictPopulate option and it doesn't work. I still get this error message

"StrictPopulateError: Cannot populate path from because it is not in your schema. Set the strictPopulate option to false to override."

how can I populate correctly a path from an array in Mongoose schema?

Answer 1

You should use nested populate:

const chat = await chatModel
  .findOne({
    $or: [
      { POne: req.user._id, PTwo: destId },
      { POne: destId, PTwo: req.user._id },
    ],
  })
  .populate([
    {
      path: 'POne',
    },
    {
      path: 'PTwo',
    },
    {
      path: 'messages',
      populate: {
        path: 'from',
      },
    },
    {
      path: 'messages',
      populate: {
        path: 'to',
      },
    },
  ]);

Also, you should define your schema references as Schema.Types.ObjectId:

const chatSchema = new Schema({
    POne: {type: Schema.Types.ObjectId, ref:'User', required: true},
    PTwo: {type: Schema.Types.ObjectId, ref:'User', required: true},
    messages:[{
      from:{type: Schema.Types.ObjectId, ref:'User', required: true},
      to:{type: Schema.Types.ObjectId, ref:'User', required: true},
      message: {type: String, required:true},
      date: {type: Date, default: Date.now}
    }]
}, {
    timestamps: true,
    toJSON: { virtuals: true }, 
    toObject: { virtuals: true },
})