I've got two models: Note and Profile. Note contains foreign key of connected profile as you can see below.
Note: {
profile_id: String,
date: String,
content: String,
}
Profile: {
id: String,
name: String,
profilePicture: String
}
I want to get all notes and also name and profile picture of note.
In this situation should I:
get all notes and all profiles and then join them locally in for loop,
get all notes and then in for loop ask DB for name and picture of matching profile,
other option
Which way is recomended?
Take a look at mongoose's Populate. You can declare a Schema property with type: Schema.Types.ObjectId, ref: 'Profile'. When you run a Query you can .populate() this field with the corresponding document.
Related
I have a following type of schema and I want populate the guide details when getting a tour document. I tried with Tour.findById(id).populate({path: 'summary.guide'}). But in the result it returns a null for guide. How to populate that guide details?
const tourSchema = new mongoose.Schema({
from: String,
to: String,
summary: {
guide: { type: Schema.Types.ObjectId, ref: 'User' },
duration: Number,
distance: Number
}
})
I think you should not pass the user id into the summary.guide object.
The second possibility is user id and summary.guide not match.
The third possibility is summary.guide is not exist.
this code works for me
Tour.findById("5dcd2c61...").populate({path: 'summary.guide'});
database noob here using MongoDB, in my program, I have users, and the core of my program are these roadmaps that I display. So, each user can create roadmaps, save others roadmaps, blah blah... Each user has a field named savedRoadmaps and createdRoadmaps which should store the roadmaps. My question is, should I just store the roadmap _ids in the savedRoadmap and createdRoadmaps field or the entire roadmap?
I am asking this because it feels like saving just the _id of the roadmaps can save storage, but it might not come in handy when I have to fetch the data of the user first, then fetch the roadmap using the roadmap ID in the user's savedRoadmap/createdRoadmap field, versus just fetching the user and the savedRoadmap field will already have the roadmap in there.
And btw, is there any sweet and brief database design read out there, please direct me to some if you know any!
For a user, I want it to have a name, email, password, description ofcourse, and also savedRoadmaps and createdRoadmaps. A user can create unlimited roadmaps and also save as much as he or she wants. For a roadmap, I want it to have a name, category, time_completion, author, date, and a roadmap object which will contain the actual json string that I will use d3 to display. Here's my User and Roadmap Schema right now:
const RoadmapSchema = new Schema({
author: {
type: String,
require: false
},
name: {
type: String,
require: true
},
category: {
type: String,
require: true
},
time_completion: {
type: Number,
require: true
},
date: {
type: Date,
default: Date.now
},
roadmap: {
type: "object",
require: true
}
});
and User Schema:
const UserSchema = new Schema({
name: {
type: String,
required: true
},
email: {
type: String,
required: true
},
password: {
type: String,
required: true
},
date: {
type: Date,
default: Date.now
},
savedRoadmap: {
type: "object",
default: []
},
createdRoadmap: {
type: "object",
default: []
}
});
My question is, inside of the savedRoadmap and createdRoadmap fields of the User schema, should I include just the _id of a roadmap, or should I include the entire json string which represents the roadmap?
There are 3 different data-modeling techniques you can use to design your roadmaps system based on the cardinality of the relationship between users and roadmaps.
In general you need to de-normalize your data model based on the queries that are expected from your application:
One to Few: Embed the N side if the cardinality is one-to-few and there is no need to access the embedded object outside the context of the parent object
One to Many: Use an array of references to the N-side objects if the cardinality is one-to-many or if the N-side objects should stand alone for any reasons
One-to-Squillions: Use a reference to the One-side in the N-side objects if the cardinality is one-to-squillions
And btw, is there any sweet and brief database design read out there,
please direct me to some if you know any!
Rules of Thumb for MongoDB Schema Design: Part 1
I used to use MySQL and now new to Mongodb. In phase of learning, I am trying to create a User Profile like LinkedIn. I am confused to choose the proper way of creating one-to-many relationship in mongodb schemas.
Context: A user can have multiple education qualification and same with experience. Here are two ways, that i tried to create the schema as:
Example 1:
var userSchema = new mongoose.Schema({
name: {
first: String,
middle: String,
last: String,
},
gender: { type: Number, max: 3, min: 0, default: GENDERS.Unspecified },
age: Number,
education: [{type: Schema.Types.ObjectId, ref:'Education'}],
experience: [{type: Schema.Types.ObjectId, ref:'Experience'}],
email: String
});
Example 2:
var userSchema = new mongoose.Schema({
name: {
first: String,
middle: String,
last: String,
},
gender: { type: Number, max: 3, min: 0, default: GENDERS.Unspecified },
age: Number,
education: [{type: String, detail: {
major: String,
degree: String,
grade: String,
startdate: Date,
enddate: Date,
remarks: String
}}],
experience: [{type: String, detail: {
position: String,
company: String,
dateofjoin: String,
dateofretire: String,
location: String,
responsibilities: [{type:String}],
description: String,
}}],
email: String
});
I haven't tested the second option.
Which one is better and easier during writing querying to fetch or add data? Is there a better way to write schema for scenarios like that?
For this particular example I would suggest embedding the documents vs storing as reference, and here is why.
Usually my first step in mongodb schema design is to consider how I will be querying the data?
Will I want to know the educational background of a user, or will I want to know all users who have a particular educational background? Having answers to these types of questions will determine how you want to setup your database.
If you already know your user, having the embedded educational background within that document is quick and easy to access. No separate queries are needed, and the schema still isn't overly complex and difficult to comprehend. This is how I would expect you would want to access the data.
Now, if you want to find all users with a particular educational background, there are obviously large drawbacks to the embedded document schema. In that case you would need to first look at each user, then loop through the education array to see all the various educations.
So the answer will be dependent on the expected queries you will be making to the data, but in this case (unless you are doing reporting on all users) then embedded is probably the way to go.
You may also find this discussion helpful:
MongoDB relationships: embed or reference?
I have a simple database in Jaydata:
$data.Entity.extend("Person", {
Name: { type: String, required: true},
LastName: {type: String, required: true},
DepartmentId: {type: int}
});
$data.EntityContext.extend("PersonDatabase", {
People : { type : $data.EntitySet, elementType : Person}
});
var Database1= new PersonDatabase("MyDatabase");
But suppose I don't know the fields of the database I have. Assume I only know the variable Database1 so I need to make a loop which returns column names(fields of "Person"). How can I make that so I can make a dynamic table which can show whatever simple database(#x columns, #y rows) data I will have?
If you have a type in hand for example the Person class, call type.getFieldNames() for and array of public mapped field names (technical fields are not visible). To access each and every field with full metadata consult type.memberDefinitions or type.memberDefinitions.toArray()
The http://admin.jaystack.net site is build with fully generic table routines powered by knockout: check out admin.jaystack.net for an example (you need to register for a free account to access the admin site)
I am creating a blog system in Node.js with mongodb as the db.
I have contents like this: (blog articles):
// COMMENTS SCHEMA:
// ---------------------------------------
var Comments = new Schema({
author: {
type: String
},
content: {
type: String
},
date_entered: {
type: Date,
default: Date.now
}
});
exports.Comments = mongoose.model('Comments',Comments);
var Tags = new Schema({
name: {
type: String
}
});
exports.Tags = mongoose.model('Tags',Tags);
// CONTENT SCHEMA:
// ---------------------------------------
exports.Contents = mongoose.model('Contents', new Schema({
title: {
type: String
},
author: {
type: String
},
permalink: {
type: String,
unique: true,
sparse: true
},
catagory: {
type: String,
default: ''
},
content: {
type: String
},
date_entered: {
type: Date,
default: Date.now
},
status: {
type: Number
},
comments: [Comments],
tags: [Tags]
}));
I am a little new to this type of database, im used to MySQL on a LAMP stack.
Basically my question is as follows:
whats the best way to associate the Contents author to a User in the
DB?
Also, whats the best way to do the tags and categories?
In MYSQL we would have a tags table and a categories table and relate by keys, I am not sure the best and most optimal way of doing it in Mongo.
THANK YOU FOR YOUR TIME!!
Couple of ideas for Mongo:
The best way to associate a user is e-mail address - as an attribute of the content/comment document - e-mail is usually a reliable unique key. MongoDB doesn't have foreign keys or associated constraints. But that is fine.
If you have a registration policy, add user name, e-mail address and other details to the users collection. Then de-normalize the content document with the user name and e-mail. If, for any reason, the user changes the name, you will have to update all the associated contents/comments. But so long as the e-mail address is there in the documents, this should be easy.
Tags and categories are best modelled as two lists in the content document, IMHO.
You can also create two indices on these attributes, if required. Depends on the access patterns and the UI features you want to provide
You can also add a document which keeps a tag list and a categories list in the contents collection and use $addToSet to add new tags and categories to this document. Then, you can show a combo box with the current tags as a starting point.
As a final point, think through the ways you plan to access the data and then design documents, collections & indices accordingly
[Update 12/9/11] Was at MongoSv and Eliot (CTO 10gen) presented a pattern relevant to this question: Instead of one comment document per user (which could grow large) have a comment document per day for a use with _id = -YYYYMMDD or even one per month depending on the frequency of comments. This optimizes index creation/document growth vs document proliferation (in case of the design where there is one comment per user).
The best way to associate the Content Authors to a User in the MongoDB, is to take an array in Author Collection which keeps an reference to User. Basically Array because One Content/Book may have multiple Authors i.e. you need to associate one Content to many Users.
The best way for category is to create a different collection in your DB and similarly as above keep a array in Contents.
I hope it helps at-least a little.