I'm trying to make a very simple thing : Populate hasMany documents (links) from an document (product)
According to Mongoose documentation about population
My Product model is like :
const modelSchema = schema({ // const schema = mongoose.Schema
[...]
_links: [{
type: schema.Types.ObjectId,
ref: 'Link'
}]
})
const Product = mongoose.model('Product', modelSchema)
and my Link model :
const modelSchema = schema({
[...]
_product: {
type: schema.Types.ObjectId,
ref: 'Product'
}
})
const Link = mongoose.model('Link', modelSchema)
I can save in both sides, find any record, populate product from Link.find().populate('_product')
but, impossible to populate links from a product :
Product
.find()
.populate('_links')
.exec(...)
-> {
_links: []
}
What I'm doing wrong ?
I've also notice that in the documentation, _id are forced to be Number, is it a part of the solution ?
Related
I am going to store a category id to an item.
I do the below .save() function to add a new row.
const myNewItem = {
categoryId = ObjectId("5fc0a6e58dc3892120595384"),
title = "Apple"
}
var myNewItemSave = await new Item(myNewItem).save();
However, when I check my database record
_id: ObjectId("..."),
categoryId: "5fc0a6e58dc3892120595384",
title: "Apple"
The categoryId is not saved as ObjectId.
I want to save it as ObjectId is because I am going to query some lookup aggregation like this:
https://mongoplayground.net/p/50y2zWj-bQ6
so I have to make localField and foreignField are the same type as ObjectId.
It happen becuse your schema don't allow category id as mongoose objectId it is string
const schema = new Mongoose.Schema(
{
title: { type: String },
categoryId: { type: Mongoose.Schema.ObjectId, ref: 'categories' }
},
{ timestamps: true, versionKey: false }
)
export default Mongoose.model('Items', schema)
Import Item model and save will convert string into mongoose objectId
const myNewItem = {
categoryId: "5fc0a6e58dc3892120595384",
title: "Apple"
}
const myNewItemSave = await Item.create(myNewItem);
#Ashok defines a type in the model, if you dont want to modify the model you can "convert" the id with mongoose.Types.ObjectId, eg:
const mongoose = require('mongoose')
const myNewItem = {
categoryId = mongoose.Types.ObjectId("5fc0a6e58dc3892120595384"),
title = "Apple"
}
I have two schemas, one collection and another category. A collection has many category and a category can have many collection items.
I'm looking to create a filter later on down the line.
category schema
const mongoose = require('mongoose')
let categorySchema = new mongoose.Schema({
name: {
type: String,
required: true,
unique: true
},
collections: [{ type: mongoose.Types.ObjectId, ref: 'Collection' }]
})
module.exports = mongoose.model('category', categorySchema)
collection schema
const mongoose = require('mongoose')
let collectionSchema = new mongoose.Schema({
...
categories: [{
type: mongoose.Schema.Types.ObjectId, ref: 'categories',
required: true
}]
})
module.exports = mongoose.model('collection', collectionSchema)
truncated this to keep it relevant.
I'm not looking to populate the references yet as I'm only doing the backend for now, so I'm only rendering JSON for now.
I can create multiple category
and I can create a collection with a category as a collection must have at least one category
I can edit a collection and add a new category
However, sometimes I seem to get the following error
I'm not sure why maybe the database hasn't updated in the app, I am using nodemon so I'm not really sure what the issue could be here.
const CollectionSchema = new Schema({
name: String
categoryName: String
});
const CategorySchema = new Schema({
name: String
});
CollectionSchema.virtual('category', {
ref: 'Category', // The model to use
localField: 'name', // Find people where `localField`
foreignField: 'categoryName', // is equal to `foreignField`
// If `justOne` is true, 'members' will be a single doc as opposed to
// an array. `justOne` is false by default.
justOne: false,
options: { sort: { name: -1 }, limit: 5 } //you can add options as well
});
const Category = mongoose.model('Category', CategorySchema);
const Collection = mongoose.model('Collection', CollectionSchema);
Collection.find({}).populate('category').exec(function(error, categories) {
/* `categories.members` is now an array of instances of `Category` */
});
This link has additional Information
Basically what I am trying to achieve is the following:
In my iOS application a QR-Code can be scanned to get the ID of a specific lounge and with that its JSON data (only ID and name for now) saved in MongoDB.
Every lounge is able (but doesn't have to) to add products to their lounge, so that in the end, after scanning the QR-Code, a customer is able to see which products are offered.
A product contains only a name and imageURL for now, but not a price, because the price can variate and be set by owners of a lounge. So a price of one and the same product can be different.
I would like to know, what the correct and best way is for implementing the schemas for that approach, so that I can easily fetch all products of a specific lounge, maybe based on its ID.
What I got so far:
lounge.js:
const mongoose = require('mongoose');
const loungeSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
name: { type: String, required: true }
});
module.exports = mongoose.model('Lounge', loungeSchema);
product.js
const mongoose = require('mongoose');
const productSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
name: { type: String, required: true },
imageURL: { type: String, required: true, unique: true }
});
module.exports = mongoose.model('Product', productSchema);
Basically you can use mongoose populate. You can achieve this by storing the products in separate collection and basically populate an array on the lounge schema using the _id for the lounge let me show you an example:
Your lounge schema would be something like this
const mongoose = require('mongoose');
const loungeSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
name: { type: String, required: true }
products: [type: Schema.Types.ObjectId, ref: 'Products' ]
});
module.exports = mongoose.model('Lounge', loungeSchema);
And your product schema
const mongoose = require('mongoose');
const productSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
name: { type: String, required: true },
imageURL: { type: String, required: true, unique: true }
});
module.exports = mongoose.model('Product', productSchema);
When saving creating a lounge just add the _id of the product to products array that apart of the lounge schema.
So basically you find the product and retrieve its _id.
To run a find query it would be something like this:
lounge.find({}).populate('products').exec();
products array will then have the related products for each lounge
Here is my Game Schema :
var mongoose = require('mongoose');
const GameSchema = new mongoose.Schema({
title: {
type: String,
required: true
},
publishers: [
{
type: mongoose.Schema.Types.ObjectId,
ref: 'Publisher'
}
]
});
var GameModel = mongoose.model('Game', GameSchema);
module.exports = GameModel;
Here is my Publisher Schema :
var mongoose = require('mongoose');
const PublisherSchema = new mongoose.Schema({
companyName: {
type: String,
required: true
},
firstParty: {
type: Boolean,
required: true
},
website: {
website: String,
}
});
var PublisherModel = mongoose.model('Publisher', PublisherSchema);
module.exports = PublisherModel;
I have a picture of what you can find in my collection "games" in mongoDB :
When I use this route :
router.get('/games', async function(req, res) {
const games = await Game
.find()
.populate('publishers')
.select('title publishers')
res.json(games);
})
I have empty arrays as result for the publishers. If I don't use an array in Schema, this is correcly populated and I got data of publisher into each game. So why mongoose doesn't populate when it is an array?
Check below by modifying the schema definition as below
I think the below could fix your issue, please give a try by redefining the publishers as below
Publishers: [
publisher: {
type: mongoose.Schema.Types.ObjectId,
ref: 'Publisher'
}
]
I think the definition of schema is more about to define the structure of the object that we would like to process, rather about the number of objects that we want to process.
The Schema definition with what I know is defining the semantics of the model and to take advantage of the middle ware functionalities.
You can save multiple objects of which meet the same semantic definition but the definition itself cannot be an array
Thanks
Pavan
I succeed to make a deep population with find and the search key in first model, but now i want to find by key on the sub object generated by the deep populate.
I have three models : Product, Category, and Event
I want to find my Products by e_fk_club_id that is in Event model
I tried two solutions but they didn't work
First solution in find :
model.find({'categories.events.e_fk_club_id':id})`
Second solution with match :
`$match : { e_fk_club_id : id }`
these are my models
product.js
var ProductSchema = new mongoose.Schema({
p_id: Number,
p_name: String,
p_fk_category: {type: mongoose.Schema.Types.ObjectId, ref: 'categories'},
}
, {collection: 'products'});
module.exports = mongoose.model('products', ProductSchema);
Category.js
var CategorySchema = new mongoose.Schema({
c_id: Number,
c_name: String,
c_fk_event: {type: mongoose.Schema.Types.ObjectId, ref: 'events'},
}
, {collection: 'categories'});
module.exports = mongoose.model('categories', CategorySchema);
Event.js
var EventSchema = new mongoose.Schema({
e_id: Number,
e_name: String,
e_fk_club_id: Number,
}
, {collection: 'events'});
module.exports = mongoose.model('events', EventSchema);
This is the code which i am trying to fetch the data :
getProductsByClub:function (id, callback){
var model = require("Product");
//model
model .find({'categories.events.e_fk_club_id':id})
.populate({
path:'p_fk_category',
model:'categories',
populate:
{
path:'e_fk_event',
model:'events',
//$match : { e_fk_club_id : id }
}
})
.exec (function(err, doc){
if (err) {
callback(err) ;
} else {
callback(doc) ;
}
})
},
Is There any solution.
Thank you in advance.