I am new to mongoose and I was strugling whole day trying to understand populate. I managed to do simple examples but now I created two schemas:
First which is UserSchema with some user details:
const UserSchema: mongoose.Schema = new mongoose.Schema ({
name: String,
email: String
});
And second which is MatchSchema witch I want to be populated with user details but I am not sure if something like this will work:
const MatchSchema: mongoose.Schema = new mongoose.Schema ({
player_one: {
id: String,
score: Number,
player_details: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User'
}
},
player_two: {
id: String,
score: Number,
player_details: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User'
}
},
winner: String
},{timestamps: true});
Probably I used something which wont work and any help will be appriciated.
You need to create a Mongoose model using the UserSchema and name it 'User'. You can then create a Match model using the MatchSchema. Assuming the UserSchema and MatchSchema are in the same file, you can add the following:
const User = mongoose.model('User', UserSchema)
const Match = mongoose.model('Match', MatchSchema)
Then when you want to populate the Match model with User data:
let data = Match.find({})
.populate('player_one.player_details')
.populate('player_two.player_details')
Related
I'm curious about the best way to represent this kind of situation in Mongo. I have my own idea, but I'm curious on what the general consensus/best practice actually would be.
Imagine I have two collections:-
Employees
--> _id
--> FirstName
--> Surname
--> Email
Comments
--> _id
--> PersonReference
--> CommentDate
--> Comment
Now imagine that Employees can come and go and the 'Employees' collection is always up-to-date. However, in the event that an employee has ever made a comment, the full information on the comment including who made it must be available.
The way I would propose to tackle this problem, is to organise the structure like this instead:-
Employees
--> _id: _id
--> FirstName: string
--> Surname: string
--> Email: string
Comments
--> _id: _id
--> CommentDate: date
--> Comment: string
[-] --> PersonReference
[+] --> Employee: object { _id: id, FirstName: string, Surname: string, Email:string }
So essentially, I would have a list of 'Active Employees' and at a time where a comment is made, I would duplicate the employee information into the Comments collection document (rather than use a reference).
From a high level perspective, is this considered best practise?
Many thanks
Duplicating the employee info in the comments collection is really a bad idea.
When an employee info needs to be changed, it will also needs to be updated in the comments.
You have a few options:
1-) Embedding the comments inside the Employee schema:
In this method we have no separate Comments collection.
If you have no need to independently query comments, this method makes sense.
This way we can access a user and his/her comments in one db access and without needing any join (populate or lookup).
The schema for this can be like this:
const mongoose = require("mongoose");
const employeeSchema = new mongoose.Schema({
firstName: String,
username: String,
email: String,
comments: [
new mongoose.Schema({
commentDate: Date,
comment: String
})
]
});
module.exports = mongoose.model("Employee", employeeSchema);
2-) Parent referencing:
In this method we keep the reference of the comments in the Employee schema.
If you don't need to access to employee from a comment, this can an option.
Employee Schema:
const mongoose = require("mongoose");
const employeeSchema = new mongoose.Schema({
firstName: String,
username: String,
email: String,
comments: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "Comment"
}
]
});
module.exports = mongoose.model("Employee", employeeSchema);
Comment Schema:
const mongoose = require("mongoose");
const commentSchema = new mongoose.Schema({
commentDate: Date,
comment: String
});
module.exports = mongoose.model("Comment", commentSchema);
3-) Child referencing
In this method we keep reference of the employee in the comments.
So if you need to access the comments from an employee we need to use Populate Virtual feature of mongoose. Becase in employee schema we don't have a reference to the comments.
Employee Schema:
const mongoose = require("mongoose");
const employeeSchema = new mongoose.Schema(
{
firstName: String,
username: String,
email: String
},
{
toJSON: { virtuals: true } // required to use populate virtual
}
);
// Populate virtual
employeeSchema.virtual("comments", {
ref: "Comment",
foreignField: "employee",
localField: "_id"
});
module.exports = mongoose.model("Employee", employeeSchema);
Comment Schema:
const mongoose = require("mongoose");
const commentSchema = new mongoose.Schema({
commentDate: Date,
comment: String,
employee: {
type: mongoose.Schema.Types.ObjectId,
ref: "Employee"
}
});
module.exports = mongoose.model("Comment", commentSchema);
4-) Both parent and child referencing:
With this method, it is possible to select comments from employee, and employee from comments. But here we have some kind of data duplication, and also when a comment is deleted, it needs to be done in both of the collections.
const mongoose = require("mongoose");
const employeeSchema = new mongoose.Schema({
firstName: String,
username: String,
email: String,
comments: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "Comment"
}
]
});
module.exports = mongoose.model("Employee", employeeSchema);
Comment Schema:
const mongoose = require("mongoose");
const commentSchema = new mongoose.Schema({
commentDate: Date,
comment: String,
employee: {
type: mongoose.Schema.Types.ObjectId,
ref: "Employee"
}
});
module.exports = mongoose.model("Comment", commentSchema);
Many database implement kind of no-delete collections, implementing a delete/active flag for each document.
For example, Employees collection would become :
Employees
--> _id: _id
--> FirstName: string
--> Surname: string
--> Email: string
--> Active: boolean
This way, you keep track on employees data that has been deleted, and prevent documents duplication if you have database size restrictions.
PS: nowadays you can be tackled keeping user data if they ask deletion (RGPD)
EDIT: This solution with boolean may not work if Employees document is updated and you want to keep employees firstname,name,mail,etc at the time he made the Comment.
If I have a model Attachment, which can be divided into 4 types: Link, YoutubeVideo, GoogleDriveFile, and GoogleDriveFolder, how can I use Mongoose to discriminate Attachment into these types, and allow them to be subdocuments in another schema; Post?
I've created the base Attachment model, and divided it into separate models using discriminators:
var AttachmentSchema = new Schema({
id: {type: String, required: true},
title: {type: String, required: true}
});
var Attachment = mongoose.model('Material', AttachmentSchema);
module.exports = {
DriveFile: Attachment.discriminator('GoogleDriveFile', new mongoose.Schema()),
DriveFolder: Attachment.discriminator('GoogleDriveFolder', new mongoose.Schema()),
Link: Attachment.discriminator('Link', new mongoose.Schema()),
YoutubeVideo: Attachment.discriminator('YoutubeVideo', new mongoose.Schema())
};
Now, in the Post schema, there should be an array of attachments, with varying types:
var Attachment = require('./attachment');
var PostSchema = new Schema(
text:{type: String},
attachments: [Material] // Could be Material.Link, Material.YoutubeVideo, etc
});
When I do this, I get an error saying "Undefined type Model at GoogleDriveFile. Did you try nesting Schemas? You can only nest using refs or arrays."
I don't know what this error means, and I can't find any docs explaining how to do this. Help?
Try doing the following:
var AttachmentSchema = new Schema({
id: {type: String, required: true},
title: {type: String, required: true}
});
var PostSchema = new Schema({
text: { type: String },
attachments: [ AttachmentSchema ] // Could be Material.Link, Material.YoutubeVideo, etc
});
var attachmentArray = PostSchema.path('attachments');
module.exports = {
Post: mongoose.model('Post', PostSchema),
DriveFile: attachmentArray.discriminator('GoogleDriveFile', new mongoose.Schema({})),
DriveFolder: attachmentArray.discriminator('GoogleDriveFolder', new mongoose.Schema({})),
Link: attachmentArray.discriminator('Link', new mongoose.Schema({})),
YoutubeVideo: attachmentArray.discriminator('YoutubeVideo', new mongoose.Schema({}))
};
The key is to NOT use a mongoose Model use the schema.path of the parent document schema as the base for your discriminators.
search for the term docArray on this link: Mongoose Discriminator documentation
I'm about to build a Node.js+Express+Mongoose app and I'd like to pick the community's brains and get some advice on best practices and going about creating an efficient schema design.
My application is going to include 2 different user types, i.e "teacher" and "student". Each will have a user profile, but will require different fields for each account type. There will also be relationships between "teacher" and "student" where a "student" will initially have 1 teacher (with the possibility of more in the future), and a "teacher" will have many students.
My initial thoughts about how to approach this is to create a general User model and a profile model for each user type (studentProfile model & teacherProfile model), then reference the appropriate profile model inside the User model, like so (A):
var UserSchema = new Schema({
name: String,
email: String,
password: String,
role: String, /* Student or Teacher */
profile: { type: ObjectID, refPath: 'role' }
});
var studentProfileSchema = new Schema({
age: Number,
grade: Number,
teachers: [{ type: ObjectID, ref: 'Teacher' }]
});
var teacherProfileSchema = new Schema({
school: String,
subject: String
});
Or do I just go ahead and directly embed all the fields for both profiles in the User model and just populate the fields required for the specific user type, like so (B):
var UserSchema = new Schema({
name: String,
email: String,
password: String,
role: String, /* Student or Teacher */
profile: {
age: Number,
grade: Number,
school: String,
subject: String
},
relationships: [{ type: ObjectID, ref: 'User' }]
});
The downside to option B is that I can't really make use of Mongoose's required property for the fields. But should I not be relying on Mongoose for validation in the first place and have my application logic do the validating?
On top of that, there will also be a separate collection/model for logging students' activities and tasks, referencing the student's ID for each logged task, i.e.:
var activitySchema = new Schema({
activity: String,
date: Date,
complete: Boolean,
student_id: ObjectID
});
Am I on the right track with the database design? Any feedback would be greatly appreciated as I value any input from this community and am always looking to learn and improve my skills. What better way than from like minded individuals and experts in the field :)
Also, you can see that I'm taking advantage of Mongoose's population feature. Is there any reason to advise against this?
Thanks again!
You could try using .discriminator({...}) function to build the User schema so the other schemas can directly "inherit" the attributes.
const options = {discriminatorKey: 'kind'};
const UserSchema = new Schema({
name: String,
email: String,
password: String,
/* role: String, Student or Teacher <-- NO NEED FOR THIS. */
profile: { type: ObjectID, refPath: 'role' }
}, options);
const Student = User.discriminator('Student', new Schema({
age: Number,
grade: Number,
teachers: [{ type: ObjectID, ref: 'Teacher' }]
}, options));
const Teacher = User.discriminator('Teacher', new Schema({
school: String,
subject: String
}, options));
const student = new Student({
name: "John Appleseed",
email: "john#gmail.com",
password: "123",
age: 18,
grade: 12,
teachers: [...]
});
console.log(student.kind) // Student
Check the docs.
One approach could be the following:
//Creating a user model for login purposes, where your role will define which portal to navigate to
const userSchema = new mongoose.Schema({
_id:mongoose.Schema.Types.ObjectId,
name: {type:String,required:true},
password: {type: String, required: true},
email: {type: String, required: true},
role:{type:String,required:true}
},{timestamps:true});
export default mongoose.model("User", userSchema);
//A student schema having imp info about student and also carrying an id of teacher from Teachers Model
const studentSchema = new mongoose.Schema({
_id:mongoose.Schema.Types.ObjectId,
age:{type:Number},
grade:{type:String},
teacher:{type:mongoose.Schema.Types.ObjectId,ref:'Teachers'}
},{timestamps:true});
export default mongoose.model("Students", studentSchema);
//A teacher model in which you can keep record of teacher
const teacherSchema = new mongoose.Schema({
_id:mongoose.Schema.Types.ObjectId,
subject:{type:String},
School:{type:String},
},{timestamps:true});
export default mongoose.model("Teachers", teacherSchema);
so I've been at it for like 4 hours, read the documentation several times, and still couldn't figure out my problem. I'm trying to do a simple populate() to my model.
I have a User model and Store model. The User has a favoriteStores array which contains the _id of stores. What I'm looking for is that this array will be populated with the Store details.
user.model
var mongoose = require('mongoose'),
Schema = mongoose.Schema;
var UserSchema = new Schema({
username: String,
name: {first: String, last: String},
favoriteStores: [{type: Schema.Types.ObjectId, ref: 'Store'}],
modifiedOn: {type: Date, default: Date.now},
createdOn: Date,
lastLogin: Date
});
UserSchema.statics.getFavoriteStores = function (userId, callback) {
this
.findById(userId)
.populate('favoriteStores')
.exec(function (err, stores) {
callback(err, stores);
});
}
And another file:
store.model
var mongoose = require('mongoose'),
Schema = mongoose.Schema;
var StoreSchema = new Schema({
name: String,
route: String,
tagline: String,
logo: String
});
module.exports = mongoose.model('Store', StoreSchema);
After running this what I get is:
{
"_id": "556dc40b44f14c0c252c5604",
"username": "adiv.rulez",
"__v": 0,
"modifiedOn": "2015-06-02T14:56:11.074Z",
"favoriteStores": [],
"name": {
"first": "Adiv",
"last": "Ohayon"
}
}
The favoriteStores is empty, even though when I just do a get of the stores without the populate it does display the _id of the store.
Any help is greatly appreciated! Thanks ;)
UPDATE
After using the deepPopulate plugin it magically fixed it. I guess the problem was with the nesting of the userSchema. Still not sure what the problem was exactly, but at least it's fixed.
I think this issue happens when schemas are defined across multiple files. To solve this, try call populate this way:
.populate({path: 'favoriteStores', model: 'Store'})
How to write multi ref for one property of one mongoose schema, like this(but wrong):
var Schema = mongoose.Schema;
var PeopleSchema = new Schema({
peopleType:{
type: Schema.Types.ObjectId,
ref: ['A', 'B'] /*or 'A, B'*/
}
})
You should add string field to your model and store external model name in it, and refPath property - Mongoose Dynamic References
var Schema = mongoose.Schema;
var PeopleSchema = new Schema({
externalModelType:{
type: String
},
peopleType:{
type: Schema.Types.ObjectId,
refPath: 'externalModelType'
}
})
Now Mongoose will populate peopleType with object from corresponding model.
In the current version of Mongoose i still don't see that multi ref possible with syntax like you want. But you can use part of method "Populating across Databases" described here. We just need to move population logic to explicitly variant of population method:
var PeopleSchema = new Schema({
peopleType:{
//Just ObjectId here, without ref
type: mongoose.Schema.Types.ObjectId, required: true,
},
modelNameOfThePeopleType:{
type: mongoose.Schema.Types.String, required: true
}
})
//And after that
var People = mongoose.model('People', PeopleSchema);
People.findById(_id)
.then(function(person) {
return person.populate({ path: 'peopleType',
model: person.modelNameOfThePeopleType });
})
.then(populatedPerson) {
//Here peopleType populated
}
...