I am creating a web app, where user can create questions. Every time user creates a question a collection should be created, where all the answers to that question should be saved as documents in that collection.
You can use mongodb ORM - mongoose for making your data models like that
var mongoose = require('mongoose')
, Schema = mongoose.Schema
var questionSchema = Schema({
title : String,
text : String,
user : { type: Schema.Types.ObjectId, ref: 'User' },
answers : [{ type: Schema.Types.ObjectId, ref: 'Answer' }]
});
var answerSchema = Schema({
user : { type: Schema.Types.ObjectId, ref: 'User' },
text : String,
});
var Question = mongoose.model('Question', questionSchema);
var Answer = mongoose.model('Answer', answerSchema);
So you will store array of answer ids inside question and can populate data:
Question.findOne().populate('answers').exec(function(err, doc){
console.log(doc.answers) // here populated answers models
})
Also you need describe User model and extend with additional data Question and Answer
Related
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 am making a small project in MEAN stack but I can not figure out what data structure to use.
So, in this case, I don't have any reference in the store I just fetch store when a person asks for his or her stores.
var personSchema = Schema({
_id : Number,
name : String,
stores: [{ type: Schema.Types.ObjectId, ref: 'Store' }]
});
var storeSchema = Schema({
_id : Number,
title : String
});
AND:
In this case, I give the store a reference of the person so when a person asks for his or her stores I fetch all the store which has a reference to the person.
var personSchema = Schema({
_id : Number,
name : String
});
var storeSchema = Schema({
_id : Number,
owner : { type: Schema.Types.ObjectId, ref: 'Person' },
title : String
});
Which one is better approach?
First one is better to use as it helps in clean code and queries.
I have a mongoose model that looks something like this
var LogSchema = new Schema({
item: {
type: ObjectId,
ref: 'article',
index:true,
},
});
But 'item' could be referenced from multiple collections. Is it possible to do something like this?
var LogSchema = new Schema({
item: {
type: ObjectId,
ref: ['article','image'],
index:true,
},
});
The idea being that 'item' could be a document from the 'article' collection OR the 'image' collection.
Is this possible or do i need to manually populate?
Question is old, but maybe someone else still looks for similar issues :)
I found in Mongoose Github issues this:
mongoose 4.x supports using refPath instead of ref:
var schema = new Schema({
name:String,
others: [{ value: {type:mongoose.Types.ObjectId, refPath: 'others.kind' } }, kind: String }]
})
In #CadeEmbery case it would be:
var logSchema = new Schema({
item: {type: mongoose.Types.ObjectId, refPath: 'kind' } },
kind: String
})
But I did't try it yet...
First of all some basics
The ref option says mongoose which collection to get data for when you use populate().
The ref option is not mandatory, when you do not set it up, populate() require you to give dynamically a ref to him using the model option.
#example
populate({ path: 'conversation', model: Conversation }).
Here you say to mongoose that the collection behind the ObjectId is Conversation.
It is not possible to gives populate or Schema an array of refs.
Some others Stackoverflow people asked about it.
Soluce 1: Populate both (Manual)
Try to populate one, if you have no data, populate the second.
Soluce 2: Change your schema
Create two link, and set one of them.
var LogSchema = new Schema({
itemLink1: {
type: ObjectId,
ref: 'image',
index: true,
},
itemLink2: {
type: ObjectId,
ref: 'article',
index: true,
},
});
LogSchema.find({})
.populate('itemLink1')
.populate('itemLink2')
.exec()
Dynamic References via refPath
Mongoose can also populate from multiple collections based on the value of a property in the document. Let's say you're building a schema for storing comments. A user may comment on either a blog post or a product.
body: { type: String, required: true },
on: {
type: Schema.Types.ObjectId,
required: true,
// Instead of a hardcoded model name in `ref`, `refPath` means Mongoose
// will look at the `onModel` property to find the right model.
refPath: 'onModel'
},
onModel: {
type: String,
required: true,
enum: ['BlogPost', 'Product']
}
});
const Product = mongoose.model('Product', new Schema({ name: String }));
const BlogPost = mongoose.model('BlogPost', new Schema({ title: String }));
const Comment = mongoose.model('Comment', commentSchema);
I have venues, which each have a comments section. Each comment is a Mongoose Comment schema. Each comment has a creator property, which is a User schema. I'm trying to find all comments a specific user has posted. How can I do this?
var VenueSchema = new mongoose.Schema({
comments: [{
type : mongoose.Schema.Types.ObjectId,
ref: 'Comment',
default: []
}]
},
{minimize: false});
var CommentSchema = new mongoose.Schema({
creator: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User'
}
}, {minimize: false});
var UserSchema = new mongoose.Schema({
token: String,
venues: [{ //in case we want users to save their favorite venues
type : mongoose.Schema.Types.ObjectId,
ref: 'Venue'
}]
});
I have tried
Venue.find({
"comments.creator": "55f1fa1263877ed0067b78c0"
}, function(err, docs) {
console.log(docs);
res.send(docs);
})
but it returns an empty array. The "55f1fa1263877ed0067b78c0" is a sample creator _id. Thanks in advance!
you cannot search creater by its id inside Venue collection becouse it collects only Comment ID. So in order to search creater by its id you need to change like below:
var VenueSchema = new mongoose.Schema({
comments: [CommentSchema]
},
{minimize: false});
var CommentSchema = new mongoose.Schema({
creator: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User'
}
}, {minimize: false});
var UserSchema = new mongoose.Schema({
token: String,
venues: [{ //in case we want users to save their favorite venues
type : mongoose.Schema.Types.ObjectId,
ref: 'Venue'
}]
});
As venueSchema is storing only ref to comments (which would be comments _id), you will not be able to query comment using venue model. Either you have embed comment document into comments array of venue schema.
Or
Just query the comment collection using comment model as below
Comment.find({
"creator": "55f1fa1263877ed0067b78c0"
}, function(err, docs) {
console.log(docs);
res.send(docs);
})
I have the following mongoose models in my express app:
//dog.js
var mongoose = require("mongoose");
var dogSchema = (exports.dogSchema = mongoose.Schema({
name: { type: String, required: true },
}));
Then I import dog.js to my user.js
//user.js
var mongoose = require("mongoose");
var dog = require("./dog");
var userSchema = mongoose.Schema({
user: { type: String, required: true },
pass: { type: String, required: true },
dogs: [dog.dogSchema],
});
Now, from my routes I am creating a new user like this:
var user = require("../models/user");
var dog = require("../models/dog");
dog = new dog.Dog(dogData);
user = new user.User(data); //this will of course contain also dogData
user.save(next);
Is this the correct way to do this kind of operation? I have the feeling that I might be generating a circular dependency somehow, and anyway it does not look right to me. Any ideas on how to create sub-documents where the schema is from another model file?
You can create simultaneous references in two directions without creating circular problems. Create a reference from one document to the other using ref. From the docs:
http://mongoosejs.com/docs/populate.html
var mongoose = require('mongoose')
, Schema = mongoose.Schema
var personSchema = Schema({
_id : Number,
name : String,
age : Number,
stories : [{ type: Schema.Types.ObjectId, ref: 'Story' }]
});
var storySchema = Schema({
_creator : { type: Number, ref: 'Person' },
title : String,
fans : [{ type: Number, ref: 'Person' }]
});
var Story = mongoose.model('Story', storySchema);
var Person = mongoose.model('Person', personSchema);
Then you can then choose to load the sub document using populate
Story.find({ --your criteria-- })
.populate('_creator')
.exec(function (err, story) {../});
You can then store the 2 schemas in separate .js files and require them both