Sencha Touch 2 Models – hasMany Associations, C# Example

In this tutorial you will learn how to use the hasMany association, a feature of Sencha Touch models that allows you to connect two models in a one-to-many relationship. The model configs you will learn about in this post are the following:

• hasMany
• belongsTo

The back-end code for this tutorial is in C#. I also published a version of this Sencha Touch tutorial using PHP.

Let’s create a simple Sencha Touch application with the following files:

In the model/Hotel.js file, you will define a Hotel model like so:

[code lang=”js”]
Ext.define(‘App.model.Hotel’, {
extend: ‘Ext.data.Model’,
config: {
fields: [
{ name: ‘id’, type: ‘int’ },
{ name: ‘name’, type: ‘string’ },
{ name: ‘address’, type: ‘string’ },
{ name: ‘status’, type: ‘int’ }
],
hasMany: {
model: ‘App.model.Room’,
name:’rooms’
}
}
});
[/code]

The interesting part of this model definition is the hasMany config, consisting of the model and name properties, which reference a Room model. You will create this model in the model/Room.js file:

[code lang=”js”]
Ext.define(‘App.model.Room’, {
extend: ‘Ext.data.Model’,
requires: [‘Ext.data.Store’],
config: {
fields: [
{ name: ‘id’, type: ‘int’ },
{ name: ‘floor’, type: ‘string’ },
{ name: ‘type’, type: ‘string’ },
{ name: ‘standardRate’, type: ‘float’ },
{ name: ‘smoking’, type: ‘string’ },
{ name: ‘status’, type: ‘int’ },
{ name: ‘hotelId’, type: ‘int’} // This works with belongsTo property below.
],
belongsTo: {
model: ‘App.model.Hotel’,
foreignKey: ‘hotelId’
},
proxy: {
type: ‘ajax’,
api: {
create: ‘../../services/rooms.ashx?act=createrooms’,
read: ‘../../services/rooms.ashx?act=loadrooms’,
update: ‘../../services/rooms.ashx?act=updaterooms’,
destroy: ‘../../services/rooms.ashx?act=eraserooms’
},
reader: {
rootProperty: ‘hotels’
}
}
}
});
[/code]

The model’s belongsTo config has a model and foreignKey properties which reference the Hotel model. The proxy config references the services/rooms.ashx page. This is the asp.net handler you will use to interact with the database.

This is the code for the rooms.ashx page:

[code lang=”csharp”]
public class Rooms : IHttpHandler
{

public void ProcessRequest(HttpContext context)
{
string roomsJson;
Room[] rooms;
string result = "{‘success’:false}";
string action = context.Request.QueryString["act"];

if (action != null)
{
switch (action.ToLower())
{
case "loadrooms":

string filterJson = context.Request.QueryString["filter"];

// Returning hard-coded rooms for demo purposes.
result = @"{‘success’:’true’,’rooms’:[{‘id’: 1, ‘floor’: ‘3’, ‘type’: ‘Royal Suite’, ‘standardRate’: ‘2’, ‘smoking’: ‘false’, ‘status’: ‘1’, ‘hotelId’: ‘1’}]}";

break;

case "createrooms":

roomsJson = GetRequestPayload(context);
rooms= JsonConvert.DeserializeObject(roomsJson, typeof(Room[])) as Room[];

// Here you would save the rooms to the database…

// Returning success for demo purposes.
result = @"{‘success’:true,’rooms’:" + JsonConvert.SerializeObject(rooms) + "}";
break;

case "updaterooms":

roomsJson = GetRequestPayload(context);
rooms = JsonConvert.DeserializeObject(roomsJson, typeof(Room[])) as Room[];

// Here you would save the rooms to the database…

// Returning success for demo purposes.
result = @"{‘success’:true,’rooms’:[" + JsonConvert.SerializeObject(rooms) + "]}";

break;

case "eraserooms":

roomsJson = GetRequestPayload(context);
rooms = JsonConvert.DeserializeObject(roomsJson, typeof(Room[])) as Room[];

// Here you would delete the rooms from the database…

// Returning success for demo purposes.
result = @"{‘success’:true}";

break;
}
}

context.Response.ContentType = "application/json";
context.Response.Write(result);
}

private string GetRequestPayload(HttpContext context)
{
StreamReader r = new StreamReader(context.Request.InputStream);
context.Request.InputStream.Position = 0;
return r.ReadToEnd();
}

public bool IsReusable
{
get
{
return false;
}
}
}
[/code]

Now you can check out the behaviors that the related models have. In the app.js file, you can try the following code:

[code lang=”js”]
Ext.application({
name: ‘App’,
models: [‘Room’, ‘Hotel’],
launch: function () {

var myHotel = Ext.create(‘App.model.Hotel’, {
id: 1,
name: ‘Siesta by the Ocean’,
address: ‘1 Ocean Front, Happy Island’,
status: 1
});

var rooms = myHotel.rooms();

rooms.each(function (item, index, length) {
console.log(‘Room Id: ‘ + item.id + ‘, room type: ‘ + item.type);
});

rooms.load(); // Should see request with: act:loadrooms, page: 1, start: 0, limit: 25, filter: [{ "property": "hotelId", "value": 1}]

}
});
[/code]

Using Google Chrome, you can browse to the index.html file, open the developer tools and inspect the request to the rooms.php file. The console’s output should look similar to this:

The query string parameters clearly show a filter property that contains the id of the hotel the rooms belong to. This is one of the behaviors that the hasMany association provides for us.

How It Works

As you can see in the code, you can obtain the rooms associated with a hotel by invoking the rooms() method of the Hotel model, which returns an instance of a data store. The method is automatically created based on the hasMany config:

[code lang=”js”]
hasMany: {
model: ‘App.model.Room’,
name:’rooms’
}
[/code]

In the app.js file, you will now add a couple of rooms to the current hotel:

[code lang=”js”]
Ext.application({
name: ‘App’,
models: [‘Room’, ‘Hotel’],
launch: function () {

var myHotel = Ext.create(‘App.model.Hotel’, {
id: 1,
name: ‘Siesta by the Ocean’,
address: ‘1 Ocean Front, Happy Island’,
status: 1
});

var rooms = myHotel.rooms();

rooms.each(function (item, index, length) {
console.log(‘Room Id: ‘ + item.id + ‘, room type: ‘ + item.type);
});

rooms.load(); // Should see request with: act:loadrooms, page: 1, start: 0, limit: 25, filter: [{ "property": "hotelId", "value": 1}]

var room1 = Ext.create(‘App.model.Room’, {
id: 1,
standardRate: 5,
floor: 3,
type: ‘Royal Suite’,
status: 1,
smoking: false
});

var room2 = Ext.create(‘App.model.Room’, {
id: 2,
standardRate: 2,
floor: 1,
type: ‘Single’,
status: 1,
smoking: false
});

rooms.add(room1);
rooms.add(room2);

rooms.sync(); // Rooms have the hotelId property populated.
}
});
[/code]

The call to rooms.sync() will upload the rooms to the server. Chrome’s console should reflect the operation:

The hotelId field of these rooms is set to 1, which is the id of their parent hotel. Note that you did not have to take care of this. It happens automatically thanks to the hasMany association you defined.

Want To Learn More?

My Sencha Touch books will teach you how to create a Sencha Touch application, step by step, from mockups to production build.

• Sencha Touch 2 Book
• Sencha Touch 1 Book

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