MongoDB Create New Document that references another Collection's Document IDs

Question

I am trying to create a new document in the Form collection. This document references many FormSection documents. Here are the Schemas:

const FormSchema = new Schema({ 
    title: {
        type: String,
        required: true,
        unique: true
    },
    description: {
        type: String,
        required: true,
        unique: true
    },
    sections: [{
        type: FormSectionDetails
    }],
    createdDate: {
        type: String,
        required: false,
        unique: true
    },
    lastEdited: {
        type: String,
        required: false,
        unique: true
    }
});

const FormSectionDetails = new Schema({
    section: {
        type: Schema.Types.ObjectId,
        ref: 'FormSection',
        required: true
    },
    position: {
        type: Number,
        required: true
    }
});

const FormSectionSchema = new Schema({ 
    name: {
        type: String,
        required: true,
        unique: true
    },
    display: {
        type: String,
        required: true,
    },
    category: {
        type: String,
        required: true
    },
...
});

let FormSection;
try {
    FormSection = mongoose.connection.model('FormSection');
} catch (e) {
    FormSection = mongoose.model('FormSection', FormSectionSchema);
}

However, when I try to add a new document to the Forms collection, I get an error:

Document being inserted:

formData = {
    "title": "Returning Members",
    "description": "Returning Members",
    "sections": 
    [{
        "section": "6292c0fbd4837faca1d85d4d",
        "position": 1
    },
  {
        "section": "6292c0fbd4837faca1d85d4e",
        "position": 2
    },
...
}

Code being run:

formdata.sections.map(s => {
   return {
       ...s,
       section: ObjectId(s.section),
   }}
);
return await FormSection.create(formdata);

Error message:

ValidationError: category: Path `category` is required., display: Path `display` is required.````

Seems like it is trying to create a new FormSection document. I don't want it to create a new FormSection document. I just want it to reference existing FormSection documents using the Object IDs I specified.

Answer 1

The Issue seems to be with how you declare the section field in the FormSchema. Try this:

 const FormSchema = new Schema({ title: { type: String, required: true, unique: true }, description: { type: String, required: true, unique: true }, sections: [{ type: ObjectId, ref: 'FormSectionDetails', required: true, }], createdDate: { type: String, required: false, unique: true }, lastEdited: { type: String, required: false, unique: true } });

This would just store the _ids of the existing FormSectionDetails

Answer 2

It turns out I was inserting the document into the wrong collection. Instead of the code snippet:

return await FormSection.create(formdata);

It should actually be:

return await Form.create(formdata);

The error message should have been a more obvious hint for me as to what the problem was.