Chapter 21: User Notifications (v0.21)

app/main/forms.py

@@ -41,3 +41,9 @@ def __init__(self, *args, **kwargs):
         if 'csrf_enabled' not in kwargs:
             kwargs['csrf_enabled'] = False
         super(SearchForm, self).__init__(*args, **kwargs)
+
+
+class MessageForm(FlaskForm):
+    message = TextAreaField(_l('Message'), validators=[
+        DataRequired(), Length(min=1, max=140)])
+    submit = SubmitField(_l('Submit'))

app/main/routes.py

@@ -5,8 +5,9 @@
 from flask_babel import _, get_locale
 from guess_language import guess_language
 from app import db
-from app.main.forms import EditProfileForm, EmptyForm, PostForm, SearchForm
-from app.models import User, Post
+from app.main.forms import EditProfileForm, EmptyForm, PostForm, SearchForm, \
+    MessageForm
+from app.models import User, Post, Message, Notification
 from app.translate import translate
 from app.main import bp
 
@@ -165,3 +166,51 @@ def search():
         if page > 1 else None
     return render_template('search.html', title=_('Search'), posts=posts,
                            next_url=next_url, prev_url=prev_url)
+
+
+@bp.route('/send_message/<recipient>', methods=['GET', 'POST'])
+@login_required
+def send_message(recipient):
+    user = User.query.filter_by(username=recipient).first_or_404()
+    form = MessageForm()
+    if form.validate_on_submit():
+        msg = Message(author=current_user, recipient=user,
+                      body=form.message.data)
+        db.session.add(msg)
+        user.add_notification('unread_message_count', user.new_messages())
+        db.session.commit()
+        flash(_('Your message has been sent.'))
+        return redirect(url_for('main.user', username=recipient))
+    return render_template('send_message.html', title=_('Send Message'),
+                           form=form, recipient=recipient)
+
+
+@bp.route('/messages')
+@login_required
+def messages():
+    current_user.last_message_read_time = datetime.utcnow()
+    current_user.add_notification('unread_message_count', 0)
+    db.session.commit()
+    page = request.args.get('page', 1, type=int)
+    messages = current_user.messages_received.order_by(
+        Message.timestamp.desc()).paginate(
+            page, current_app.config['POSTS_PER_PAGE'], False)
+    next_url = url_for('main.messages', page=messages.next_num) \
+        if messages.has_next else None
+    prev_url = url_for('main.messages', page=messages.prev_num) \
+        if messages.has_prev else None
+    return render_template('messages.html', messages=messages.items,
+                           next_url=next_url, prev_url=prev_url)
+
+
+@bp.route('/notifications')
+@login_required
+def notifications():
+    since = request.args.get('since', 0.0, type=float)
+    notifications = current_user.notifications.filter(
+        Notification.timestamp > since).order_by(Notification.timestamp.asc())
+    return jsonify([{
+        'name': n.name,
+        'data': n.get_data(),
+        'timestamp': n.timestamp
+    } for n in notifications])

app/models.py

@@ -1,5 +1,6 @@
 from datetime import datetime
 from hashlib import md5
+import json
 from time import time
 from flask import current_app
 from flask_login import UserMixin
@@ -72,6 +73,15 @@ class User(UserMixin, db.Model):
         primaryjoin=(followers.c.follower_id == id),
         secondaryjoin=(followers.c.followed_id == id),
         backref=db.backref('followers', lazy='dynamic'), lazy='dynamic')
+    messages_sent = db.relationship('Message',
+                                    foreign_keys='Message.sender_id',
+                                    backref='author', lazy='dynamic')
+    messages_received = db.relationship('Message',
+                                        foreign_keys='Message.recipient_id',
+                                        backref='recipient', lazy='dynamic')
+    last_message_read_time = db.Column(db.DateTime)
+    notifications = db.relationship('Notification', backref='user',
+                                    lazy='dynamic')
 
     def __repr__(self):
         return '<User {}>'.format(self.username)
@@ -121,6 +131,17 @@ def verify_reset_password_token(token):
             return
         return User.query.get(id)
 
+    def new_messages(self):
+        last_read_time = self.last_message_read_time or datetime(1900, 1, 1)
+        return Message.query.filter_by(recipient=self).filter(
+            Message.timestamp > last_read_time).count()
+
+    def add_notification(self, name, data):
+        self.notifications.filter_by(name=name).delete()
+        n = Notification(name=name, payload_json=json.dumps(data), user=self)
+        db.session.add(n)
+        return n
+
 
 @login.user_loader
 def load_user(id):
@@ -137,3 +158,25 @@ class Post(SearchableMixin, db.Model):
 
     def __repr__(self):
         return '<Post {}>'.format(self.body)
+
+
+class Message(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    sender_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    recipient_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    body = db.Column(db.String(140))
+    timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
+
+    def __repr__(self):
+        return '<Message {}>'.format(self.body)
+
+
+class Notification(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String(128), index=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    timestamp = db.Column(db.Float, index=True, default=time)
+    payload_json = db.Column(db.Text)
+
+    def get_data(self):
+        return json.loads(str(self.payload_json))

app/templates/base.html

@@ -32,6 +32,16 @@
                     {% if current_user.is_anonymous %}
                     <li><a href="{{ url_for('auth.login') }}">{{ _('Login') }}</a></li>
                     {% else %}
+                    <li>
+                        <a href="{{ url_for('main.messages') }}">{{ _('Messages') }}
+                            {% set new_messages = current_user.new_messages() %}
+                            <span id="message_count" class="badge"
+                                  style="visibility: {% if new_messages %}visible
+                                                     {% else %}hidden{% endif %};">
+                                {{ new_messages }}
+                            </span>
+                        </a>
+                    </li>
                     <li><a href="{{ url_for('main.user', username=current_user.username) }}">{{ _('Profile') }}</a></li>
                     <li><a href="{{ url_for('auth.logout') }}">{{ _('Logout') }}</a></li>
                     {% endif %}
@@ -115,5 +125,25 @@
                 }
             );
         });
+        function set_message_count(n) {
+            $('#message_count').text(n);
+            $('#message_count').css('visibility', n ? 'visible' : 'hidden');
+        }
+        {% if current_user.is_authenticated %}
+        $(function() {
+            var since = 0;
+            setInterval(function() {
+                $.ajax('{{ url_for('main.notifications') }}?since=' + since).done(
+                    function(notifications) {
+                        for (var i = 0; i < notifications.length; i++) {
+                            if (notifications[i].name == 'unread_message_count')
+                                set_message_count(notifications[i].data);
+                            since = notifications[i].timestamp;
+                        }
+                    }
+                );
+            }, 10000);
+        });
+        {% endif %}
     </script>
 {% endblock %}

app/templates/messages.html

@@ -0,0 +1,22 @@
+{% extends "base.html" %}
+
+{% block app_content %}
+    <h1>{{ _('Messages') }}</h1>
+    {% for post in messages %}
+        {% include '_post.html' %}
+    {% endfor %}
+    <nav aria-label="...">
+        <ul class="pager">
+            <li class="previous{% if not prev_url %} disabled{% endif %}">
+                <a href="{{ prev_url or '#' }}">
+                    <span aria-hidden="true">&larr;</span> {{ _('Newer messages') }}
+                </a>
+            </li>
+            <li class="next{% if not next_url %} disabled{% endif %}">
+                <a href="{{ next_url or '#' }}">
+                    {{ _('Older messages') }} <span aria-hidden="true">&rarr;</span>
+                </a>
+            </li>
+        </ul>
+    </nav>
+{% endblock %}

app/templates/send_message.html

@@ -0,0 +1,11 @@
+{% extends "base.html" %}
+{% import 'bootstrap/wtf.html' as wtf %}
+
+{% block app_content %}
+    <h1>{{ _('Send Message to %(recipient)s', recipient=recipient) }}</h1>
+    <div class="row">
+        <div class="col-md-4">
+            {{ wtf.quick_form(form) }}
+        </div>
+    </div>
+{% endblock %}

app/templates/user.html

@@ -28,6 +28,9 @@ <h1>{{ _('User') }}: {{ user.username }}</h1>
                     </form>
                 </p>
                 {% endif %}
+                {% if user != current_user %}
+                <p><a href="{{ url_for('main.send_message', recipient=user.username) }}">{{ _('Send private message') }}</a></p>
+                {% endif %}
             </td>
         </tr>
     </table>