rewrite tutorial docs and example

examples/tutorial/flaskr/__init__.py

@@ -0,0 +1,48 @@
+import os
+
+from flask import Flask
+
+
+def create_app(test_config=None):
+    """Create and configure an instance of the Flask application."""
+    app = Flask(__name__, instance_relative_config=True)
+    app.config.from_mapping(
+        # a default secret that should be overridden by instance config
+        SECRET_KEY='dev',
+        # store the database in the instance folder
+        DATABASE=os.path.join(app.instance_path, 'flaskr.sqlite'),
+    )
+
+    if test_config is None:
+        # load the instance config, if it exists, when not testing
+        app.config.from_pyfile('config.py', silent=True)
+    else:
+        # load the test config if passed in
+        app.config.update(test_config)
+
+    # ensure the instance folder exists
+    try:
+        os.makedirs(app.instance_path)
+    except OSError:
+        pass
+
+    @app.route('/hello')
+    def hello():
+        return 'Hello, World!'
+
+    # register the database commands
+    from flaskr import db
+    db.init_app(app)
+
+    # apply the blueprints to the app
+    from flaskr import auth, blog
+    app.register_blueprint(auth.bp)
+    app.register_blueprint(blog.bp)
+
+    # make url_for('index') == url_for('blog.index')
+    # in another app, you might define a separate main index here with
+    # app.route, while giving the blog blueprint a url_prefix, but for
+    # the tutorial the blog will be the main index
+    app.add_url_rule('/', endpoint='index')
+
+    return app