Guide applies to: classic

Building a Login System

One of the most frequently requested tutorials is how to make a login system. We’re going to start off this ongoing tutorial by building just that. Please note that this is only one way of creating a login system. There are many other viable options. This is simply meant to show you an approach to creating an application with login/logout functionality.

Disclaimer: This tutorial is meant to show users one way in which they can design an application to contain a “logged in” and “logged out” view. This tutorial does not attempt to achieve secure data connections, session management, true authentication, etc. It is for educational purposes only.

Step 1 - Generate your Application

The first thing we want to do is generate an application using Sencha Cmd. You can do so by issuing the following command from your command line interface, or CLI:

sencha -sdk /path/to/ExtSDK generate app TutorialApp ./TutorialApp

Note: If you do not have Sencha Cmd, or are unfamiliar with using it, please read the Cmd Introduction guide before proceeding.

The resulting TutorialApp is a fully functional Cmd generated application that we will use as a foundation for our login/logout application. You can view this application by navigating to the application’s location on your webserver. For instance:

http://localhost/TutorialApp

Or by starting “sencha app watch” from within the newly generated TutorialApp folder. This will spin up a Jetty server, which removes the need for a traditional web server. If you use “sencha app watch”, you can find the application here:

http://localhost:1841/

Step 2 - Create the Login View Components

Next, we’re going to navigate to our newly generated TutorialApp. Drill down into your generated application’s “app/view/“ folder. You should see the default generated “main” folder. This folder contains the Main.js, MainController.js, and MainModel.js files.

Let’s go ahead and prepare our project for the login functionality by creating a new app/view folder called “login”. After creating the “app/view/login/“ folder, add the following files to said folder:

- Login.js
- LoginController.js

The resulting file structure should look like this:

Step 3 - Disable mainView

The mainView config of application is a very handy way to automatically load and instantiate “TutorialApp.view.main.Main” by utilizing the Viewport Plugin. However, we have some evaluations to perform in Ext.application’s launch method prior to picking our initial view. For instance, we do not want to create the Main view if the user is not yet logged in.

For the purposes of this exercise, let’s remove the mainView config from the application config in “{appRoot}/app.js”.

Note: Since we have removed mainView, refreshing your application will result in a blank page as no classes are being instantiated.

Step 4 - Create the Login Window

Next, let’s create a login view. To do this, we’ll open our blank “{appRoot}/app/view/login/Login.js” file and begin defining the Login Window.

First, let’s define our Class and extend the base Window class. That looks like so:

Ext.define('TutorialApp.view.login.Login', {
    extend: 'Ext.window.Window',
    xtype: 'login'
});

Now, we’ve defined our Login class as an extension of Ext.window.Window, which can be instantiated using the xtype login. Let’s start giving our class some unique properties. We’ll start by adding some additional configurations to the window itself.

Ext.define('TutorialApp.view.login.Login', {
    extend: 'Ext.window.Window',
    xtype: 'login'
    requires: [
        'TutorialApp.view.login.LoginController',
        'Ext.form.Panel'
    ],
    controller: 'login',
    bodyPadding: 10,
    title: 'Login Window',
    closable: false,
    autoShow: true
});

Let’s walk through what these configurations mean.

requires

The requires block makes sure that we’re including any classes that may be relied upon before instantiating our Login window. We need to include LoginController.js because we’re about to designate it as our controller on the next line. We also need to include Ext.form.Panel since our view contains a Form panel.

controller

The controller config designates a ViewController, which will then be attached to instances of the Login window. This controller provides a place to include all logic relating to the Login window or its child components. Here, we designate controller to be login, which will be our controller’s alias.

bodyPadding

The bodyPadding config is purely aesthetic. This config applies “10px” of padding around the exterior of the window’s body content.

title

The string passed to the title config results in the creation of a header and adds the string value as its title.

closable

closable determines whether or not the window can be closed. Windows have a closable button by default. However, since this is a login window, we don’t want the user closing it. If they DID close it, they would be left with a blank page.

autoShow

Windows are hidden by default. Setting autoShow to true will show the Window once it’s created. The alternative would be call the Window’s show method programmatically when we want the Window to be visible.

Now that we’ve discussed the Window’s configuration, let’s give it some child components. Since this will be a login form, we’ll create a Form panel as a child of the Window. Then we’ll add two Text fields, a Display field, and a submit Button.

The final code for this file should appear as follows:

Ext.define('TutorialApp.view.login.Login', {
    extend: 'Ext.window.Window',
    xtype: 'login',
    requires: [
        'TutorialApp.view.login.LoginController',
        'Ext.form.Panel'
    ],
    controller: 'login',
    bodyPadding: 10,
    title: 'Login Window',
    closable: false,
    autoShow: true,
    items: {
        xtype: 'form',
        reference: 'form',
        items: [{
            xtype: 'textfield',
            name: 'username',
            fieldLabel: 'Username',
            allowBlank: false
        }, {
            xtype: 'textfield',
            name: 'password',
            inputType: 'password',
            fieldLabel: 'Password',
            allowBlank: false
        }, {
            xtype: 'displayfield',
            hideEmptyLabel: false,
            value: 'Enter any non-blank password'
        }],
        buttons: [{
            text: 'Login',
            formBind: true,
            listeners: {
                click: 'onLoginClick'
            }
        }]
    }
});

Let’s discuss these additions.

Window items

The first configuration we’ve added to the Login window is the items config. In containers, like the Form panel and the Login window itself, the items config may hold a Component or a Component configuration object. The items config may also be an array of Components or Component config objects. These Components will be displayed in the Container’s body using the Container’s layout.

xtype

Every Component class has it’s own xtype. You can think of an xtype as a shortcut to easily create an instance of a Component. In this case, we have configured the Login window with a child item with an xtype of “form” (“form” being the xtype of the Ext.form.Panel class). Form panels are special types of Panels that include convenient configuration options for working with input fields.

Form Items

Next, you’ll see the familiar face of another items array. Here we’re nesting additional items by using the items array a level deeper. We’re placing more Components inside of the parent component, which is the Form panel. In this case, our nested Components are the form fields that make up the login form.

We can walk quickly through this array of components as they’re pretty self explanatory. The first item has an xtype of [[ext: Ext.form.field.Text textfield]], a name of “username”, a fieldLabel of “username”, and allowBlank of “false”. This boils down to a textfield with a name value and a field label. The field cannot be left blank and pass validation (see “formBind” below).

The next field is almost identical aside from the type being set to “password”. This turns your input into * for security’s sake.

The last member of this items array is a displayfield. A Display field is a text field that is not submitted with your form. It’s useful for conveying data without the user interacting with said data. In this case, we’re notifying the user that any non-blank password will allow the form to be submitted.

buttons

The last bit that we’ve added here is a buttons array. This is a convenience config used for adding Buttons to a footer Toolbar in your panel. This particular button will contain the text ‘Login’ and will be what users will click to submit the login form.

formBind

Our Button contains a config called formBind, which is set to “true”. When a Component has formBind set to “true”, it will be disabled/enabled depending on the validity state of the Form. This means that the Button will not be clickable until the two input fields contain values.

listeners

The listeners object is configured with events and the methods / functions that will respond to the firing of those events. In this case, we’re waiting for someone to click the Button. Upon a click, we “forward” the event to a method called onLoginClick. The onLoginClick method will later be defined in our Login controller.

Note: We have not yet instantiated the Login view in any way, so refreshing the application will not show any changes.

Step 5 - Add Login Logic

Next, let’s create the Login controller, which is a class that contains any logic used to handle user interactions with the Login view. To do this, we’ll open our blank {appRoot}/app/view/login/LoginController.js file and begin defining our Login window’s logic.

The entirety of LoginController.js is as follows:

Ext.define('TutorialApp.view.login.LoginController', {
    extend: 'Ext.app.ViewController',
    alias: 'controller.login',
    onLoginClick: function() {
        // This would be the ideal location to verify the user's credentials via
        // a server-side lookup. We'll just move forward for the sake of this example.
        // Set the localStorage value to true
        localStorage.setItem("TutorialLoggedIn", true);
        // Remove Login Window
        this.getView().destroy();
        // Add the main view to the viewport
        Ext.widget('app-main');
    }
});

The above code may be a little out of context, but it will make more sense when we discuss the launch method in the next section. This class contains the onLoginClick method that is called by clicking on the login button.

These bits of code have annotations to describe each statement’s purpose, but let’s look at them piece by piece for further explanation.

onLoginClick()

First of all, we’re creating a method called onLoginClick. This is the method to which we directed our login button’s click event in the Login view.

As mentioned in the comments, this is where you’d call your server to verify that the user’s credentials are valid. This would generally come in the form of an AJAX or REST request. However, for this tutorial, we will accept any non-blank input. Upon success, you’d follow through with the rest of the code. On failure, you would allow the user to re-enter their credentials. Of course, there’s no failure possibility in this case, so let’s move forward!

localStorage

We are utilizing localStorage in this tutorial to maintain user login state. After a successful credentials check, we can determine that the user has the appropriate access to the Main application view. We can then set a key/value pair in localStorage to let the application know that the user is valid. Next, we will check that the TutorialLoggedIn localStorage key is set to “true” in our initial launch method (covered in more detail in the “launch” section below).

getView()

ViewControllers introduce a very helpful method called getView(). The getView() method returns the current view associated with the ViewController from which it is called. In this case, the view is the Login window. Since we’re treating the login click as a successful login, we no longer want to present the Login window. So, we are using this.getView().destroy() to get a reference to the Login window and then destroy it.

Ext.widget(‘app-main’)

Now that we’ve destroyed the Login window, we want to change the view to display the Main view. In this case, we use Ext.widget('app-main') to instantiate the “{appRoot}/app/view/main/Main.js” view.

Note: 'app-main' refers to the xtype that is defined on our Sencha Cmd generated “TutorialApp.view.main.Main” class located in “{appRoot}/app/view/main.Main.js”.

Step 6 - Add Launch Logic to Application.js

Next, let’s discuss “{appRoot}/app/Application.js” and the launch function.

“Application.js” is the heart of your application. You can find “Application.js” at the same level as your “view”, “store”, and “model” folders. It provides a handy method called launch, which fires when your application has loaded all of its required classes. Here is the full code for this tutorial’s “Application.js” file.

/**
 * The main application class. An instance of this class is created by `app.js` when it calls
 * Ext.application(). This is the ideal place to handle application launch and initialization
 * details.
 */
Ext.define('TutorialApp.Application', {
    extend: 'Ext.app.Application',
    name: 'TutorialApp',
    stores: [
        // TODO: add global / shared stores here
    ],
    views: [
        'TutorialApp.view.login.Login',
        'TutorialApp.view.main.Main'
    ],
    launch: function () {
        // It's important to note that this type of application could use
        // any type of storage, i.e., Cookies, LocalStorage, etc.
        var loggedIn;
        // Check to see the current value of the localStorage key
        loggedIn = localStorage.getItem("TutorialLoggedIn");
        // This ternary operator determines the value of the TutorialLoggedIn key.
        // If TutorialLoggedIn isn't true, we display the login window,
        // otherwise, we display the main view
        Ext.widget(loggedIn ? 'app-main' : 'login');
    }
});

Let’s examine what these pieces are doing.

requires

We’ve already described what requires does, but let’s touch on this particular array. For the purposes of “Application.js”, we need to prepare the application to load either the Login or Main view, depending on the results of the logged in evaluation to come. To that end, we must require both “TutorialApp.view.main.Main” and “TutorialApp.view.login.Login” so that either result is available.

launch

As previously mentioned, the launch method is a function that executes when your application has loaded everything it needs to run. This is an ideal place to perform logic regarding user state for a login/logout application.

localStorage.getItem()

Tthe next step is to check for a previously set localStorage key called TutorialLoggedIn. We are simply setting the loggedIn variable to the result of that key’s value. If it doesn’t exist, loggedIn will be null. If it does exist, we’ve previously set TutorialLoggedIn to be true in our LoginController’s logic.

Widget Ternary

Most programming languages contain a form of conditional shorthand called ternary operators. Ternary operators allow you to minimize the amount of code required for a traditional if/else statement. In this case, we’re using a ternary to say, “if loggedIn exists (isn’t null), let’s load the Main view, otherwise, load the Login view”. We are then using the Ext.widget method to instantiate the result of the ternary operator.

Step 7 - Add Viewport Plugin

As you may remember, we removed the mainView config from “{appRoot}/app.js” early on in this tutorial. Since we don’t have a Viewport defined, your Main view will not know where to render. We are going to change that by mixing in the viewport plugin so that “{appRoot}/app/view/main/Main.js” will operate as our application’s viewport This way, the Main view takes up all available width and height within the browser. It’s as simple as adding the following line to “{appRoot}/app/view/main/Main.js”:

plugins: 'viewport',

Our resulting {appRoot}/app/view/main/Main.js file will look like this:

/**
 * This class is the main view for the application. It is specified in `app.js` as the
 * "mainView" property. That setting automatically applies the "viewport"
 * plugin to promote that instance of this class to the body element.
 *
 * TODO - Replace this content of this view to suite the needs of your application.
 */
Ext.define('TutorialApp.view.main.Main', {
    extend: 'Ext.container.Container',
    requires: [
        'TutorialApp.view.main.MainController',
        'TutorialApp.view.main.MainModel'
    ],
    xtype: 'app-main',
    controller: 'main',
    plugins: 'viewport',
    viewModel: {
        type: 'main'
    },
    layout: {
        type: 'border'
    },
    items: [{
        xtype: 'panel',
        bind: {
            title: '{name}'
        },
        region: 'west',
        html: '<ul><li>This area is commonly used for navigation, for example, using a "tree" component.</li></ul>',
        width: 250,
        split: true,
        tbar: [{
            text: 'Button',
            handler: 'onClickButton'
        }]
    },{
        region: 'center',
        xtype: 'tabpanel',
        items:[{
            title: 'Tab 1',
            html: '<h2>Content appropriate for the current navigation.</h2>'
        }]
    }]
});

You do not need to modify any of the other pieces of “{appRoot}/app/view/main/Main.js” since we will be using the default generated onClickButton method for our click handler.

Step 8 - Add Main Logic

We’re almost finished! All that’s left now is to give the user some way to logout of the application, which will destroy the TutorialLoggedIn key from localStorage. This logic should take place in the “{appRoot}/app/view/main/MainController.js” file. You can remove the other generated code if you like. This is the final definition of “MainController.js” for this tutorial:

Ext.define('TutorialApp.view.main.MainController', {
    extend: 'Ext.app.ViewController',
    alias: 'controller.main',
    onClickButton: function () {
        // Remove the localStorage key/value
        localStorage.removeItem('TutorialLoggedIn');
        // Remove Main View
        this.getView().destroy();
        // Add the Login Window
        Ext.widget('login');
    }
});

We shouldn’t need to go into much depth here since it is basically the inverse of our {appRoot}/app/view/login/LoginController.js code.

To summarize this functionality, onClickButton is the function that is called by the button handler in our generated “{appMain}/app/view/main/Main.js” view. Once the click event is detected, the following steps are taken:

• Remove the localStorage key that maintains the user’s logged in state.

• Destroy the current view, which is TutorialApp.view.main.Main.

• Recreate the login view.

You should now be able to load your application in your browser and see a fully functioning login/logout application.

Wrap Up

We hope that you have enjoyed this tutorial. This is simply the foundation for an application, but hopefully we have introduced a few concepts that make your future projects simpler. Please feel free to suggest ideas for future tutorials via our forums. Also, feel free to follow up with questions via the support portal or forums.