1-n, 1-1

https://stackoverflow.com/questions/32038793/one-to-one-relationship-with-mongoose

First of all, there is a huge difference between relationships in MongoDB and those in SQL based datastores (you need to be clear about this from the get-go).

Relationships in MongoDB are just representations of related data. There is no mechanism which maintains the integrity of these relationships.

What mongoose does with refs is just use the field having the ref option to query the _id field of documents in the referenced collection. This is used for operations like populate (which internally calls findById queries on the target collection and replaces the referenced field with the documents).

This being cleared, you can store one or many IDs for the referenced collection in the field, thus creating one-to-one or one-to-many “relationships”.

'use strict';

console.log("creating schema object...");

var mongoose = require('mongoose');

var Schema = mongoose.Schema;

// event attendee

var eventAttendee = new mongoose.Schema({

phone: {type: String},

registered: Boolean

});

// event location

var location = new mongoose.Schema({

address: {type: String},

city: {type: String},

province: {type: String},

zip: {type: String}

});

module.exports = mongoose.model('Events', new Schema({

Event_Title: {type: String},

Event_Description: {type: String},

Event_Date: {type: Date, default: Date.now},

Event_Location: {type:location, default:null}, // 1 to 1

Created_Date: {type: Date, default: Date.now},

Author: {type: String},

attendees: [eventAttendee] // 1 to n

}, {collection: "funEvents"}));

console.log("Attach our schema object to string 'Events', Then register it as a model");

Add the event

app.route('/events')

.get(eventList.list_all_events)

.post(eventList.create_event);

Open up postman. select POST. In the the url, type in http://localhost/events

In Node express code, we have stated that for post verbs at url /events, we want it to hit create_event function. And create_event function is where we implement getting the data from the body object, and saving it into the database.

body:

Then check the database to verify.

{ "_id" : ObjectId("5a2f3f9b8f4a4a4367dbf59e"), "Event_Title" : "Super Badminton", "Event_Description" : "Play some badminton with fellow friends", "Author" : "Ricky T", "attendees" : [ ], "Created_Date" : ISODate("2017-12-12T02:31:55.180Z"), "Event_Location" : null, "Event_Date" : ISODate("2017-12-12T02:31:55.180Z"), "__v" : 0 }

Look at the object id 5a2f3f9b8f4a4a4367dbf59e. We use this as the event id that we will be adding attendees to.

Add attendee(s) to the event (1 to n)

In order to register the attendee, we use postman.
given the route code:

1 2	app.route('/events/:eventId/:phoneId') .post(eventList.registerAttendee);

we do the following.

web verb: POST
url: http://localhost/events/5a2f3f9b8f4a4a4367dbf59e

Notice that the last param is a phoneId. We just give a phone number like so:

url: http://localhost/events/5a2f3f9b8f4a4a4367dbf59e/13510083852

When the user put this in the browser, it will hit the registerAttendee function in node express. The registerAttendee function will look for name and phone in its request object’s body:

1	event.attendees.push(createAttendeeObject(req.body.phone,req.body.name));

Hence, as we can see, it gets the properties phone and name from the body, create an object out of it, and pushes it onto the attendees’ array property.

So in your post man, click on body, highlight x-www-form-urlencoded, and enter key/values:

Essentially, we are entering the properties that are needed by the eventAttendee schema:

// event attendee

var eventAttendee = new mongoose.Schema({

phone: {type: String},

registered: Boolean

});

Once you press Send on postman, the attendee should be in. Check the database:

> db.funEvents.find()

result:

{ “_id” : ObjectId(“5a2f3f9b8f4a4a4367dbf59e”),
“Event_Title” : “Super Badminton”,
“Event_Description” : “Play some badminton with fellow friends”,
“Author” : “Ricky T”,
“attendees” : [ { “phone” : “135103483252”, “name” : “Hannah Hong”, “registered” : false, “_id” : ObjectId(“5a2f405a8f4a4a4367dbf59f”) } ],
“Created_Date” : ISODate(“2017-12-12T02:31:55.180Z”),
“Event_Location” : null,
“Event_Date” : ISODate(“2017-12-12T02:31:55.180Z”), “__v” : 1 }

You will see that the attendees array now has the user Hannah Hong.

You can add as many users as you like as this is 1 to n. One event, many users.

Adding the location (1 to 1)

Adding the location to our event involves hitting the url at /events/:eventId
with a PUT verb:

eventListRoutes.js

app.route('/events/:eventId')

.get(eventList.read_event)

.put(eventList.update_event)

.delete(eventList.delete_event);

We put the event id at the end of the url like so: http://localhost/events/5a2f3f9b8f4a4a4367dbf59e

web verb: PUT
url: http://localhost/events/5a2f3f9b8f4a4a4367dbf59e

We add the information for the location via the body through

body => x-www-form-urlencoded:

address:132 Children’s park, hai yue, Shekou
city:Shenzhen
province: Guangdong
zip: 2847384

hit the “Send” button.

Finally, check your database:

> db.funEvents.find()

result:

{ “_id” : ObjectId(“5a2f3f9b8f4a4a4367dbf59e”),
“Event_Title” : “Super Badminton”,
“Event_Description” : “Play some badminton with fellow friends”,
“Author” : “Ricky T”,
“attendees” : [ { “phone” : “13510083852”, “name” : “Hannah Hong”, “registered” : false, “_id” : ObjectId(“5a2f405a8f4a4a4367dbf59f”) } ],
“Created_Date” : ISODate(“2017-12-12T02:31:55.180Z”),
“Event_Location” : { “_id” : ObjectId(“5a2f4195a713254374cbceee”), “zip” : “2847384”, “province” : “Guangdong”, “city” : “Shenzhen”, “address” : “132 Children’s park, hai yue, Shekou” },
“Event_Date” : ISODate(“2017-12-12T02:31:55.180Z”), “__v” : 1 }

Further References

Installing Mongoose

npm install mongoose –-save

Everything in Mongoose starts with a Schema. Each schema maps to a MongoDB collection and defines the shape of the documents within that collection.

/model/person.js

// grab the things we need

var mongoose = require('mongoose');

var Schema = mongoose.Schema;

// create a schema

var userSchema = new Schema({

username: { type: String, required: true, unique: true },

password: { type: String, required: true },

admin: Boolean,

location: String,

meta: {

age: Number,

website: String

created_at: Date,

updated_at: Date

}, { collection: 'person'});

//the collection means the custom name of the collection you want to appear in your mongo database. Hence you would do something like db.person.find() to see all entries of your 'person' collection.

// custom method to add string to end of name

// you can create more important methods like name validations or formatting

// you can also do queries and find similar users

userSchema.methods.dudify = function() {

// add some stuff to the users name

this.name = this.name + '-dude';

return this.name;

};

// the schema is useless so far

// we need to create a model using it

var Person = mongoose.model('person', userSchema);

// make this available to our users in our Node applications

module.exports = Person;

/app.js

var express = require('express');

var mongoose = require('mongoose');

var app = express();

var port = 3000;

//Lets connect to our database using the DB server URL.

mongoose.connect('mongodb://localhost/PersonDatabase');

var db = mongoose.connection;

db.on('error', console.error.bind(console, 'connection error:'));

db.once('open', function (callback) {

// yay!

console.log('mongoose db connected');

});

// if our user.js file is at app/models/person.js

var Person = require('./models/person');

//enter person data

app.get('/person', function(req, res){

var paramUN = req.query.username;

console.log('username param is: ' + paramUN);

if(paramUN !== undefined) {

// create a new user called chris

var somePerson = new Person({

username: paramUN,

password: 'compaq',

admin: true

});

// call the custom method. this will just add -dude to his name

// user will now be Ricky-dude

somePerson.dudify(function(err, name) {

if (err) throw err;

console.log('Your new name is ' + name);

});

// call the built-in save method to save to the database

somePerson.save(function(err) {

try {

if (err) throw err; //throw error

}

catch(err){

res.send("Sorry, person with username "

+ paramUN

+ ", already exists. please try another");

return;

}

console.log('Person saved successfully!');

res.send("Person saved successfully!");

});

}

else {

console.log('paramUN is NOT valid.');

res.send("Person NOT saved....param is not valid");

}

});

app.listen(port, function() {

console.log('7:26pm running on port ' + port);

});

Find all People

//find all people

app.get('/admin/findall', function(req, res){

Person.find({}, function(err, people){

try {

if(err) throw err;

console.log(people);

res.type('application/json');

res.send(people);

}

catch(err) {

res.send(err);

return;

}

});

Find one person

//find one person

app.get('/admin/find', function(req, res){

var paramUN = req.query.username;

console.log('username param is: ' + paramUN);

Person.find({ username: paramUN }, function(err, person) {

try {

if (err) throw err;

res.type('application/json');

res.send(person);

}

catch(err){

res.send("User not found, " + err);

return;

}

});

Removing Users

app.get('/admin/remove', function(req, res){

var unParam = req.query.username;

// get the user starlord55

Person.find({ username: unParam }, function(err, person) {

if (err) throw err;

if(person!==undefined){

console.log('person found!' + person);

// delete person

Person.remove({username: unParam}, function(err) {

res.send('User successfully deleted!');

});

}

});

Chinese Rule of Eight

Tag Archives: mongoose

Using mongoose

1-n, 1-1

Add the event

Add attendee(s) to the event (1 to n)

Adding the location (1 to 1)

Further References

Installing Mongoose

/model/person.js

/app.js

Find all People

Find one person

Removing Users