Say I have one model, Book, and another model, Genre. When I create the book, I'd like to be able to pass a Genre ID and have the model automatically fetch and embed the document. For example:
const bookSchema = new Schema({
title: {
type: String,
required: true,
},
author: {
type: String,
required: true,
},
genre: {
type: ObjectId,
required: true,
}
});
const genreSchema = new Schema({
name: {
type: String,
required: true,
},
});
Then I'd like to be create a book as follows:
const Book = await Book.create({
title: 'Lord of the Rings',
author: 'J. R. R. Tolkien',
genre: '5d6ede6a0ba62570afcedd3a',
});
That would create a book and automatically embed the genre document from the given ID. Is there a way to do that from within the schema, or would I have to wrap it in additional logic?
You can use the pre-save mongoose middleware/hook to find the genre and set it as an embedded document. In mongoose pre-save hook, this will be the current document, you can read the value and set the value to this object before it is written to the database.
Note that, since this is a pre-save hook, it will be run only on Model.create() or document.save(). So it won't be run on Model.insertMany(). But it will be run when you update the document using document.save(). If you want to set the genre only on new documents, you will have to check for this.isNew property
const { Schema, Types } = mongoose
const genreSchema = new Schema({
name: {
type: String,
required: true,
},
});
const Genre = mongoose.model('Genre', genreSchema)
const bookSchema = new Schema({
title: {
type: String,
required: true,
},
author: {
type: String,
required: true,
},
genreId: {
type: Schema.Types.ObjectId,
required: true,
},
genre: {
type: genreSchema,
},
});
bookSchema.pre('save', async function() {
if (this.isNew) { // this.isNew will be true on only new documents
this.genre = await Genre.findById(this.genreId) // `this` is the new book document
}
})
const Book = mongoose.model('Book', bookSchema)
/* Test book creation */
const genre = await Genre.create({
name: 'Fantasy'
})
const book = await Book.create({
title: 'Lord of the Rings',
author: 'J. R. R. Tolkien',
genreId: genre._id,
});
console.log(book)
you can use mixed schema type and document middleware to solve your problem.see my sample code below:
const genreSchema = new mongoose.Schema({
name: {
type: String,
required: true,
},
});
const Genre = mongoose.model('Genre', genreSchema);
const bookSchema = new mongoose.Schema({
title: {
type: String,
required: true,
},
author: {
type: String,
required: true,
},
genre: {
type: Object,
required: true,
}
});
bookSchema.pre('save', async function () {
const genreID = mongoose.Types.ObjectId(this.genre);
this.genre = await Genre.findById(genreID);
});
const Book = mongoose.model('Book', bookSchema);
const newBook = new Book({ title: 'The book', author: 'xyz', genre: '5ef55c67be27fb2a08a1131c' });
newBook.save();
How do you know which genre ID to embed? Can you send this from your frontend?
If yes, then simply select the genre ID from you frontend and then pass it in your API's request body.
While in your backend:
router.route('/book')
.post((req, res) => {
Book.create({
title: req.body.title,
author: req.body.author,
genre: req.body.genre,
}, (err, product) => {
if (err) {
res.send(err);
} else {
res.json({success:true})
}
});
})
Do something like this to create a new book object in your Book collection.
If I understand your question correctly I think what you're looking for is populate. https://mongoosejs.com/docs/populate.html
It would change your schema to look like the following
const bookSchema = new Schema({
title: {
type: String,
required: true,
},
author: {
type: String,
required: true,
},
genre: {
type: Schema.Types.ObjectId,
ref: 'Genre',
required: true,
}
});
const genreSchema = new Schema({
name: {
type: String,
required: true,
},
});
When you get your book you can reference the genre by doing this
Book.find()
.populate('genre')
Hopefully, that answered your question!
Related
I have an array of objectIDs references in mongo. I want to get a specific element in that array after populating the objectIDs. the problem is i get an empty array.
Here's my schema
// Patient Schema - start
const patientSchema = new mongoose.Schema({
nom: {
type: String,
required:true
},
prénom: {
type: String,
required:true
},
naissance:{
type:Date,
},
adresse: {
type: String,
required:true
},
téléphone: {
type: String,
required:true
},
profession: {
type: String,
},
/// the field i'm trying to populate
consultations:[{
type: mongoose.Schema.Types.ObjectId,
ref:'Consultation'
}],
salle:{
type: mongoose.Schema.Types.ObjectId,
required: true,
ref:'Salle'
},
date:{
type:String,
default: Date.now
},
jointes: {
type:Array
},
questionnaire: {
type:Object
},
}, { collection : 'patients'} );
const patients = mongoose.model('Patient', patientSchema);
Consultation schema
const consultationSchema = new mongoose.Schema({
date: {
type: String,
required:true
},
motif:{
type: String,
},
observations: [{
type: mongoose.Schema.Types.ObjectId,
ref: "Observation"
}],
paiements: [{
type: mongoose.Schema.Types.ObjectId,
ref: "Paiement"
}],
ordonnances: [{
type: mongoose.Schema.Types.ObjectId,
ref: "Ordonnance"
}]
});
const consultations = mongoose.model('Consultation', consultationSchema);
the exports
module.exports = {
patients: patients,
consultations: consultations,
}
The router where i'm trying to populaet consultation field and then get the item
const {patients} = require('./patient.models')
const {consultations} = require('./patient.models')
// not working , getting empty array
const patient = await patients.find({"consultations.motif" : "Checking"}).populate('consultations')
res.send(patient)
The mongo db record , to show you that the field does exist
Here's what i get when i do make the following query iwthout specifiying the field
const patient = await patients.find().populate('consultations')
res.send(patient)
This question already has been answered here: Find after populate mongoose
Here is the solution for your case which does not involve changing the database structure:
const patient = await patients.find().populate({
path: 'consultations',
match: {
motif: 'Checking'
}
})
res.send(patient)
I'm trying to populate my post's author fields (which is are object ids) with the corresponding author objects which are in a separate collection.
My controller code is as follows:
exports.readPosts = async (req, res) => {
try {
const posts = await Post.find({ board: req.params.board });
await posts.populate("author").execPopulate();
res.send(posts);
} catch (err) {
res.status(400).send(err.message);
}
};
I'm at a loss as to why this isn't working as I have very similar code in another controller method that is working just fine.
All help greatly appreciated.
Below is the relevant Model file:
const mongoose = require("mongoose");
const postSchema = new mongoose.Schema(
{
title: {
type: String,
required: true,
trim: true,
},
content: { type: String, required: true, trim: true },
comments: [
{
comment: {
type: String,
required: true,
trim: true,
},
user: {
type: mongoose.Schema.Types.ObjectId,
ref: "User",
},
date: {
type: Date,
default: Date.now(),
},
},
],
author: {
type: mongoose.Schema.Types.ObjectId,
required: true,
ref: "User",
},
board: {
type: mongoose.Schema.Types.ObjectId,
required: true,
ref: "Board",
},
},
{ timestamps: true }
);
const Post = mongoose.model("Post", postSchema);
module.exports = Post;
posts is an array of models. populate must be called on a model. The preferred way to do this is at query time. It probably works on your other controller because you are using a findOne so it is returning the model, not the Array.
const posts = Post
.find({ board: req.params.board })
.populate('author')
.exec();
I have 2 schemas:
const mongoose = require('mongoose');
const PinSchema = new mongoose.Schema({
title: String,
content: String,
image: String,
latitude: Number,
longitude: Number,
author: {
type: mongoose.Schema.ObjectId,
ref: "User"
},
comments: [
{
text: String,
createdAt: {
type: Date,
default: Date.now,
author: {
type: mongoose.Schema.ObjectId,
ref: "User"
}
}
}
]
}, { timestamps: true });
module.exports = mongoose.model("Pin", PinSchema);
and
const mongoose = require('mongoose');
const UserSchema = new mongoose.Schema({
name: String,
email: String,
picture: String
});
module.exports = mongoose.model("User", UserSchema);
As you can see author field in Pin is the same as the _id in User schema.
I then try to populate the comments author field in the Pin schema like this:
const pinUpdated = await Pin.findOneAndUpdate(
{ _id: pinId },
{ $push: { comments: "some comment" } },
{ new: true }
).populate("author")
.populate("comments.author");
however the result object has author field set to null so population doesn't work.
I'm not against doing this with native mongo syntax using $lookup but in my case it's not just looking up an array it's looking up a field of an objects array:
db.pins.aggregate([
{
$lookup:
{
from: "users",
localField: "comments._id", // this won't work
foreignField: "_id",
as: "authorOutput"
}
}
])
what am I missing in populate()?
It looks like your author field in the comments array is nested inside the createdAt object, which is likely unintentional. Changing PinSchema to the following (closing curly brace before author) should fix it:
const PinSchema = new mongoose.Schema({
...
comments: [
{
text: String,
createdAt: {
type: Date,
default: Date.now,
},
author: {
type: mongoose.Schema.ObjectId,
ref: "User"
}
}
]
}, { timestamps: true });
These the response for user that Im getting from get request to profile API
"user": "5cc3a4e8d37a7259b45c97fe"
What I'm looking for instead is
"user":{
"_id": "5cc3a4e8d37a7259b45c97fe",
"name":"Jhon Doe",
}
Here is my code:
Profile.findOne({
user: req.user.id
})
.populate('user',['name']) // I added this line to populate user object with name
.then(profile=>{
if(!profile){
errors.noprofile = 'There is no profile for this user'
return res.status(404).json(errors);
}
res.json(profile)
})
.catch(err => res.status(404).json(err));
However, Im getting these error:
{
"message": "Schema hasn't been registered for model \"users\".\nUse mongoose.model(name, schema)",
"name": "MissingSchemaError"
}
What am I missing
Profile Schema
const ProfileSchema = new Schema({
user:{
type: Schema.Types.ObjectId,
ref: 'users'
},
handle: {
type: String,
required: true,
max: 40
},
company: {
type: String
},
website: {
type: String,
}
})
Here is how my Users schema looks like
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
// Create Schema
const UserSchema = new Schema({
name:{
type: String,
required: true,
},
email:{
type: String,
required: true,
},
password:{
type: String,
required: true,
},
avator:{
type: String,
},
date:{
type: Date,
default: Date.now,
}
});
module.exports = User = mongoose.model('Users', UserSchema)
Schema that you are referencing in Profile schema is users, but you have saved your user schema as Users. So I would say that you need to update your Profile schema:
const ProfileSchema = new Schema({
user:{
type: Schema.Types.ObjectId,
ref: 'Users'
},
handle: {
type: String,
required: true,
max: 40
},
company: {
type: String
},
website: {
type: String,
}
})
Name under which is saved your User schema can be found in this line
module.exports = User = mongoose.model('Users', UserSchema)
The error says you don't have Schema for Users. You reference it from Profile Schema, but you don't have it. It can be this way:
const Users = new Schema({
name: String
})
I have a ProfileSchema that I want to keep track of posts that have been posted. When I save a new Post it has a Profile_id but when I fetch the profile entry the posts array is empty. How does this work?
Profile Schema
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const ProfileSchema = new mongoose.Schema({
user: {
type: Schema.Types.ObjectId,
ref: 'users'
},
handle: {
type: String,
required: true,
max: 40
},
posts: [
{
type: Schema.Types.ObjectId,
ref: 'posts'
}
],date:{
type: Date,
default: Date.now
}
})
module.exports = Profile = mongoose.model('profile', ProfileSchema);
Post Schema
const PostSchema = new Schema({
user: {
type: Schema.Types.ObjectId,
ref: 'users'
},
profile: {
type: Schema.Types.ObjectId,
ref: 'profile'
},
title: {
type: String,
required: true,
max: 40
},
body: {
type: String,
required: true
},
date: {
type: Date,
default: Date.now
}
})
module.exports = Profile = mongoose.model('posts', PostSchema)
how I save it
router.post('/', passport.authenticate('jwt', {session: false}), (req,res) => {
const newPost = new Post({
title: req.body.title,
body: req.body.body,
img: req.body.img,
user: req.user._id,
profile: req.body.profile_id
});
newPost.save().then(post => res.json(post));
})
I'm a bit confused the mongoose documentation uses syntax I'm not familiar with or haven't learned their way yet. my user populates when I fetch for the profile data but the posts array is blank when I populate it.