How to build a message delivery status in Django

Today, we will make a realtime message delivery status framework with Django and Pusher. A basic understanding of Django and Vue is needed in order to follow this tutorial.

Setting up Django to build message delivery status framework

First, we need to install the Python Django library if we don’t already have it.
To install Django, we run:

bash
1pip install django
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After installing Django, it’s time to create our project. Open up a terminal, and create a new project using the following command:

bash
1django-admin startproject pusher_message
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In the above command, we created a new project called pusher_message. The next step will be to create an app inside our new project. To do that, let’s run the following commands:

bash
1//change directory into the pusher_message directory
2    cd pusher_message
3    //create a new app where all our logic would live
4    django-admin startapp message
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Once we are done setting up the new app, we need to tell Django about our new application, so we will go into our pusher_message\settings.py and add the message app to our installed apps as seen below:

python
1INSTALLED_APPS = [
2        'django.contrib.admin',
3        'django.contrib.auth',
4        'django.contrib.contenttypes',
5        'django.contrib.sessions',
6        'django.contrib.messages',
7        'django.contrib.staticfiles',
8        'message'
9    ]
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After doing the above, it’s time for us to run the application and see if all went well.
In our terminal shell, we run:

python
1python manage.py runserver
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If we navigate our browser to http://localhost:8000, we should see the following:

Set up an App on Pusher

At this point, Django is ready and set up. We now need to set up Pusher, as well as grab our app credentials.
We need to sign up on Pusher and create a new app, and also copy our secret, application key and application id.

The next step is to install the required libraries:

python
1pip install pusher
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In the above bash command, we installed one package, pusher. This is the official Pusher library for Python, which we will be using to trigger and send our messages to Pusher.

Creating Our Application

First, let us create a model class, which will generate our database structure.
Let’s open up message\models.py and replace the content with the following:

python
1from django.db import models
2
3    from django.contrib.auth.models import User
4    # Create your models here.
5    class Conversation(models.Model):
6        user = models.ForeignKey(User, on_delete=models.CASCADE)
7        message = models.CharField(blank=True, null=True, max_length=225)
8        status = models.CharField(blank=True, null=True, max_length=225)
9        created_at = models.DateTimeField(auto_now=True)
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In the above block of code, we defined a model called Conversation. The conversation table consists of the following fields:

• A field to link the message to the user that created it
• A field to store the message
• A field to store the status of the message
• A filed to store the date and time the message was created

Running Migrations
We need to make migrations and also run them, so our database table can be created. To do that, let us run the following in our terminal:

python
1python manage.py makemigrations
2
3    python manage.py migrate
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Creating Our Views.
In Django, the views do not necessarily refer to the HTML structure of our application. In fact, we can see it as our Controller as referred to in some other frameworks.
Let us open up our views.py in our message folder and replace the content with the following:

python
1from django.shortcuts import render
2    from django.contrib.auth.decorators import login_required
3    from django.views.decorators.csrf import csrf_exempt
4    from pusher import Pusher
5    from .models import *
6    from django.http import JsonResponse, HttpResponse
7
8    # instantiate pusher
9    pusher = Pusher(app_id=u'XXX_APP_ID', key=u'XXX_APP_KEY', secret=u'XXX_APP_SECRET', cluster=u'XXX_APP_CLUSTER')
10    # Create your views here.
11    #add the login required decorator, so the method cannot be accessed withour login
12    @login_required(login_url='login/')
13    def index(request):
14        return render(request,"chat.html");
15
16    #use the csrf_exempt decorator to exempt this function from csrf checks
17    @csrf_exempt
18    def broadcast(request):
19        # collect the message from the post parameters, and save to the database
20        message = Conversation(message=request.POST.get('message', ''), status='', user=request.user);
21        message.save();
22        # create an dictionary from the message instance so we can send only required details to pusher
23        message = {'name': message.user.username, 'status': message.status, 'message': message.message, 'id': message.id}
24        #trigger the message, channel and event to pusher
25        pusher.trigger(u'a_channel', u'an_event', message)
26        # return a json response of the broadcasted message
27        return JsonResponse(message, safe=False)
28
29    #return all conversations in the database
30    def conversations(request):
31        data = Conversation.objects.all()
32        # loop through the data and create a new list from them. Alternatively, we can serialize the whole object and send the serialized response 
33        data = [{'name': person.user.username, 'status': person.status, 'message': person.message, 'id': person.id} for person in data]
34        # return a json response of the broadcasted messgae
35        return JsonResponse(data, safe=False)
36
37    #use the csrf_exempt decorator to exempt this function from csrf checks
38    @csrf_exempt
39    def delivered(request, id):
40
41        message = Conversation.objects.get(pk=id);
42        # verify it is not the same user who sent the message that wants to trigger a delivered event
43        if request.user.id != message.user.id:
44            socket_id = request.POST.get('socket_id', '')
45            message.status = 'Delivered';
46            message.save();
47            message = {'name': message.user.username, 'status': message.status, 'message': message.message, 'id': message.id}
48            pusher.trigger(u'a_channel', u'delivered_message', message, socket_id)
49            return HttpResponse('ok');
50        else:
51            return HttpResponse('Awaiting Delivery');
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In the code above, we have defined four main functions which are:

• index
• broadcast
• conversation
• delivered

In the index function, we added the login required decorator, and we also passed the login URL argument which does not exist yet, as we will need to create it in the urls.py file. Also, we rendered a default template called chat.html which we will also create soon.
In the broadcast function, we retrieved the content of the message being sent, saved it into our database, we finally trigger a Pusher request passing in our message dictionary, as well as a channel and event name.
In the conversations function, we simply grab all conversations and return them as a JSON response
Finally, we have the delivered function, which is the function which takes care of our message delivery status.
In this function, we get the conversation by the ID supplied to us, we then verify that the user who wants to trigger the delivered event isn’t the user who sent the message in the first place. Also, we pass in the socket_id so that Pusher does not broadcast the event back to the person who triggered it.
The socket_id stands as an identifier for the socket connection that triggered the event.

Populating The URL’s.py
Let us open up our pusher_message\urls.py file and replace with the following:

python
1"""pusher_message URL Configuration
2
3    The `urlpatterns` list routes URLs to views. For more information please see:
4        https://docs.djangoproject.com/en/1.11/topics/http/urls/
5    Examples:
6    Function views
7        1. Add an import:  from my_app import views
8        2. Add a URL to urlpatterns:  url(r'^$', views.home, name='home')
9    Class-based views
10        1. Add an import:  from other_app.views import Home
11        2. Add a URL to urlpatterns:  url(r'^$', Home.as_view(), name='home')
12    Including another URLconf
13        1. Import the include() function: from django.conf.urls import url, include
14        2. Add a URL to urlpatterns:  url(r'^blog/', include('blog.urls'))
15    """
16    from django.conf.urls import url
17    from django.contrib import admin
18    from django.contrib.auth import views
19    from message.views import *
20
21    urlpatterns = [
22        url(r'^$', index),
23        url(r'^admin/', admin.site.urls),
24        url(r'^login/$', views.login, {'template_name': 'login.html'}), 
25        url(r'^logout/$', views.logout, {'next_page': '/login'}),
26        url(r'^conversation$', broadcast),
27        url(r'^conversations/$', conversations),
28        url(r'^conversations/(?P<id>[-\w]+)/delivered$',delivered)
29    ]
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What has changed in this file? We have added 6 new routes to the file.
We have defined the entry point, and have assigned it to our index function. Next, we defined the login URL, which the login_required decorator would try to access to authenticate users. We have used the default auth function to handle it but passed in our own custom template for login, which we will create soon.
Next, we defined the routes for the conversation message trigger, all conversations, and finally the delivered conversation.

Creating the H****TML Files
Now we will need to create two HTML pages, so our application can run smoothly. We have referenced two HTML pages in the course of building the application which are:

• login.html
• chat.html

Let us create a new folder in our messages folder called templates.
Next, we create a file called login.html in our templates folder and replace it with the following:

html
1<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
2      {% if form.errors %}
3
4    <center><p>Your username and password didn't match. Please try again.</p></center>
5    {% endif %}
6
7    {% if next %}
8        {% if user.is_authenticated %}
9
10    <center><p>Your account doesn't have access to this page. To proceed,
11        please login with an account that has access.</p></center>
12        {% else %}
13
14    <center><p>Please login to see this page.</p></center>
15        {% endif %}
16    {% endif %}
17
18    <div class="container">
19        <div class="row">
20            <div class="col-md-4 col-md-offset-4">
21                <div class="login-panel panel panel-default">
22                    <div class="panel-heading">
23                        <h3 class="panel-title">Please Sign In</h3>
24                    </div>
25                    <div class="panel-body">
26                        <form method="post" action="">
27    {% csrf_token %}
28
29                            <p class="bs-component">
30                                <table>
31                                    <tr>
32                                        <td>{{ form.username.label_tag }}</td>
33                                        <td>{{ form.username }}</td>
34                                    </tr>
35                                    <tr>
36                                        <td>{{ form.password.label_tag }}</td>
37                                        <td>{{ form.password }}</td>
38                                    </tr>
39                                </table>
40                            </p>
41                            <p class="bs-component">
42                                <center>
43                                    <input class="btn btn-success btn-sm" type="submit" value="login" />
44                                </center>
45                            </p>
46                            <input type="hidden" name="next" value="{{ next }}" />
47                        </form>
48                    </div>
49                </div>
50            </div>
51        </div>
52    </div>
53
54Next, let us create the `chat.html` file and replace it with the following:
55
56     <html>
57        <head>
58            <title>
59            </title>
60        </head>
61        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"/>
62        <script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.3.2/vue.js"></script>
63        <script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.16.1/axios.min.js"></script>
64        <script src="//js.pusher.com/4.0/pusher.min.js"></script>
65        <style>
66            .chat
67    {
68        list-style: none;
69        margin: 0;
70        padding: 0;
71    }
72
73    .chat li
74    {
75        margin-bottom: 10px;
76        padding-bottom: 5px;
77        border-bottom: 1px dotted #B3A9A9;
78    }
79
80    .chat li.left .chat-body
81    {
82        margin-left: 60px;
83    }
84
85    .chat li.right .chat-body
86    {
87        margin-right: 60px;
88    }
89
90
91    .chat li .chat-body p
92    {
93        margin: 0;
94        color: #777777;
95    }
96
97    .panel .slidedown .glyphicon, .chat .glyphicon
98    {
99        margin-right: 5px;
100    }
101
102    .panel-body
103    {
104        overflow-y: scroll;
105        height: 250px;
106    }
107
108    ::-webkit-scrollbar-track
109    {
110        -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3);
111        background-color: #F5F5F5;
112    }
113
114    ::-webkit-scrollbar
115    {
116        width: 12px;
117        background-color: #F5F5F5;
118    }
119
120    ::-webkit-scrollbar-thumb
121    {
122        -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,.3);
123        background-color: #555;
124    }
125
126        </style>
127        <body>
128            <div class="container" id="app">
129        <div class="row">
130            <div class="col-md-12">
131                <div class="panel panel-primary">
132                    <div class="panel-heading">
133                        <span class="glyphicon glyphicon-comment"></span> Chat
134
135                    </div>
136                    <div class="panel-body">
137                        <ul class="chat" id="chat" >
138                           <li class="left clearfix" v-for="data in conversations">
139                            <span class="chat-img pull-left" >
140                               <img :src="'http://placehold.it/50/55C1E7/fff&amp;text='+data.name" alt="User Avatar" class="img-circle"/> 
141                            </span>
142                                <div class="chat-body clearfix">
143                                    <div class="header">
144                                        <strong class="primary-font" v-html="data.name">  </strong> <small class="pull-right text-muted" v-html="data.status"></small>
145                                    </div>
146                                    <p v-html="data.message">
147
148                                    </p>
149                                </div>
150                            </li>
151                        </ul>
152                    </div>
153                    <div class="panel-footer">
154                        <div class="input-group">
155                            <input id="btn-input" v-model="message" class="form-control input-sm" placeholder="Type your message here..." type="text">
156                            <span class="input-group-btn">
157                                <button class="btn btn-warning btn-sm" id="btn-chat" @click="sendMessage()">
158                                    Send</button>
159                            </span>
160                        </div>
161                    </div>
162                </div>
163            </div>
164        </div>
165    </div>
166    </body>
167    </html>
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Vue Component And Pusher Bindings
That’s it! Now, whenever a new message is delivered, it will be broadcast and we can listen using our channel to update the status in realtime.
Below is our Example component written using Vue.js
Please note: In the Vue component below, a new function called **queryParams** was defined to serialize our POST body so it can be sent as **x-www-form-urlencoded** to the server in place of as a **payload**. We did this because Django cannot handle requests coming in as **payload**.

javascript
1<script>
2        var pusher = new Pusher('XXX_APP_KEY',{
3          cluster: 'XXX_APP_CLUSTER'
4        });
5        var socketId = null;
6        pusher.connection.bind('connected', function() {
7            socketId = pusher.connection.socket_id;
8
9        });
10
11        var my_channel = pusher.subscribe('a_channel');
12        var config = { headers: { 'Content-Type': 'application/x-www-form-urlencoded' } };
13        new Vue({
14            el: "#app",
15            data: {
16                    'message': '',
17                    'conversations': []
18            },
19            mounted() {
20                this.getConversations();
21                this.listen();
22
23            },
24            methods: {
25                sendMessage() {
26                    axios.post('/conversation', this.queryParams({message: this.message}), config)
27                        .then(response => {
28                            this.message = '';
29                        });
30                },
31                getConversations() {
32                    axios.get('/conversations').then((response) => {
33                        this.conversations = response.data;
34                        this.readall();
35                    });  
36                },
37                listen() {
38                    my_channel.bind("an_event", (data)=> {
39                        this.conversations.push(data);
40                        axios.post('/conversations/'+ data.id +'/delivered', this.queryParams({socket_id: socketId}));
41                    })
42
43                     my_channel.bind("delivered_message", (data)=> {
44                        for(var i=0; i < this.conversations.length; i++){
45                            if (this.conversations[i].id == data.id){
46                                this.conversations[i].status = data.status;
47                            }
48                        }
49
50                    })
51                },
52                readall(){
53
54                      for(var i=0; i < this.conversations.length; i++){
55                            if(this.conversations[i].status=='Sent'){
56                                axios.post('/conversations/'+ this.conversations[i].id +'/delivered');
57                            }
58                        }
59
60                },
61                queryParams(source) {
62                    var array = [];
63
64                    for(var key in source) {
65                        array.push(encodeURIComponent(key) + "=" + encodeURIComponent(source[key]));
66                    }
67
68                    return array.join("&");
69                    }
70            }
71        });
72    </script>
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Below is the image demonstrating what we have built:

Conclusion

In this article, we have covered how to create a realtime message delivery status using Django and Pusher. We have gone through exempting certain functions from CSRF checks, as well as exempting the broadcaster from receiving an event they triggered.
The code is hosted on public Github repository . You can download it for educational purposes.
Have a better way we could have built our application, reservations or comments, let us know in the comments. Remember, sharing is learning.