Chapter 9: Pagination (v0.9)

app/forms.py

@@ -46,3 +46,8 @@ class EditProfileForm(FlaskForm):
             user = User.query.filter_by(username=self.username.data).first()
             if user is not None:
                 raise ValidationError('Please use a different username.')
+
+
+class PostForm(FlaskForm):
+    post = TextAreaField('Say something', validators=[DataRequired()])
+    submit = SubmitField('Submit')

app/routes.py

@@ -3,8 +3,8 @@ from flask import render_template, flash, redirect, url_for, request
 from flask_login import login_user, logout_user, current_user, login_required
 from werkzeug.urls import url_parse
 from app import app, db
-from app.forms import LoginForm, RegistrationForm, EditProfileForm
-from app.models import User
+from app.forms import LoginForm, RegistrationForm, EditProfileForm, PostForm
+from app.models import User, Post
 
 
 @app.before_request
@@ -14,21 +14,41 @@ def before_request():
         db.session.commit()
 
 
-@app.route('/')
-@app.route('/index')
+@app.route('/', methods=['GET', 'POST'])
+@app.route('/index', methods=['GET', 'POST'])
 @login_required
 def index():
-    posts = [
-        {
-            'author': {'username': 'John'},
-            'body': 'Beautiful day in Portland!'
-        },
-        {
-            'author': {'username': 'Susan'},
-            'body': 'The Avengers movie was so cool!'
-        }
-    ]
-    return render_template('index.html', title='Home', posts=posts)
+    form = PostForm()
+    if form.validate_on_submit():
+        post = Post(body=form.post.data, author=current_user)
+        db.session.add(post)
+        db.session.commit()
+        flash('Your post is now live!')
+        return redirect(url_for('index'))
+    page = request.args.get('page', 1, type=int)
+    posts = current_user.followed_posts().paginate(
+        page, app.config['POSTS_PER_PAGE'], False)
+    next_url = url_for('index', page=posts.next_num) \
+        if posts.has_next else None
+    prev_url = url_for('index', page=posts.prev_num) \
+        if posts.has_prev else None
+    return render_template('index.html', title='Home', form=form,
+                           posts=posts.items, next_url=next_url,
+                           prev_url=prev_url)
+
+
+@app.route('/explore')
+@login_required
+def explore():
+    page = request.args.get('page', 1, type=int)
+    posts = Post.query.order_by(Post.timestamp.desc()).paginate(
+        page, app.config['POSTS_PER_PAGE'], False)
+    next_url = url_for('explore', page=posts.next_num) \
+        if posts.has_next else None
+    prev_url = url_for('explore', page=posts.prev_num) \
+        if posts.has_prev else None
+    return render_template('index.html', title='Explore', posts=posts.items,
+                           next_url=next_url, prev_url=prev_url)
 
 
 @app.route('/login', methods=['GET', 'POST'])
@@ -74,11 +94,15 @@ def register():
 @login_required
 def user(username):
     user = User.query.filter_by(username=username).first_or_404()
-    posts = [
-        {'author': user, 'body': 'Test post #1'},
-        {'author': user, 'body': 'Test post #2'}
-    ]
-    return render_template('user.html', user=user, posts=posts)
+    page = request.args.get('page', 1, type=int)
+    posts = user.posts.order_by(Post.timestamp.desc()).paginate(
+        page, app.config['POSTS_PER_PAGE'], False)
+    next_url = url_for('user', username=user.username, page=posts.next_num) \
+        if posts.has_next else None
+    prev_url = url_for('user', username=user.username, page=posts.prev_num) \
+        if posts.has_prev else None
+    return render_template('user.html', user=user, posts=posts.items,
+                           next_url=next_url, prev_url=prev_url)
 
 
 @app.route('/edit_profile', methods=['GET', 'POST'])

app/templates/_post.html

@@ -1,6 +1,6 @@
     <table>
         <tr valign="top">
             <td><img src="{{ post.author.avatar(36) }}"></td>
-            <td>{{ post.author.username }} says:<br>{{ post.body }}</td>
+            <td><a href="{{ url_for('user', username=post.author.username) }}">{{ post.author.username }}</a> says:<br>{{ post.body }}</td>
         </tr>
     </table>

app/templates/base.html

@@ -10,6 +10,7 @@
         <div>
             Microblog:
             <a href="{{ url_for('index') }}">Home</a>
+            <a href="{{ url_for('explore') }}">Explore</a>
             {% if current_user.is_anonymous %}
             <a href="{{ url_for('login') }}">Login</a>
             {% else %}
@@ -28,5 +29,5 @@
         {% endif %}
         {% endwith %}
         {% block content %}{% endblock %}
-    </body>
+  </body>
 </html>

app/templates/index.html

@@ -2,7 +2,26 @@
 
 {% block content %}
     <h1>Hi, {{ current_user.username }}!</h1>
+    {% if form %}
+    <form action="" method="post">
+        {{ form.hidden_tag() }}
+        <p>
+            {{ form.post.label }}<br>
+            {{ form.post(cols=32, rows=4) }}<br>
+            {% for error in form.post.errors %}
+            <span style="color: red;">[{{ error }}]</span>
+            {% endfor %}
+        </p>
+        <p>{{ form.submit() }}</p>
+    </form>
+    {% endif %}
     {% for post in posts %}
-    <div><p>{{ post.author.username }} says: <b>{{ post.body }}</b></p></div>
+        {% include '_post.html' %}
     {% endfor %}
+    {% if prev_url %}
+    <a href="{{ prev_url }}">Newer posts</a>
+    {% endif %}
+    {% if next_url %}
+    <a href="{{ next_url }}">Older posts</a>
+    {% endif %}
 {% endblock %}

app/templates/user.html

@@ -23,4 +23,10 @@
     {% for post in posts %}
         {% include '_post.html' %}
     {% endfor %}
+    {% if prev_url %}
+    <a href="{{ prev_url }}">Newer posts</a>
+    {% endif %}
+    {% if next_url %}
+    <a href="{{ next_url }}">Older posts</a>
+    {% endif %}
 {% endblock %}

config.py

@@ -13,3 +13,4 @@ class Config(object):
     MAIL_USERNAME = os.environ.get('MAIL_USERNAME')
     MAIL_PASSWORD = os.environ.get('MAIL_PASSWORD')
     ADMINS = ['your-email@example.com']
+    POSTS_PER_PAGE = 25