123 lines
2.8 KiB
Markdown
123 lines
2.8 KiB
Markdown
---
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title: Flask Day 1
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date: 2016-02-15 01:23:33
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tags:
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- flask
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---
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### "Hello World" in Flask
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Create a folder named `microblog` (or whatever you want). Then cd into that folder and run following prompt in terminal:
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``` bash
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$ python3 -m venv flask
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```
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Now you'll have a folder named `flask` inside `microblog`, containing a private version of Python interpreter.
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And you should install **flask** and extensions by the commands below:
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``` bash
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$ flask/bin/pip install flask
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$ flask/bin/pip install flask-login
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$ flask/bin/pip install flask-openid
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$ flask/bin/pip install flask-mail
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$ flask/bin/pip install flask-sqlalchemy
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$ flask/bin/pip install sqlalchemy-migrate
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$ flask/bin/pip install flask-whooshalchemy
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$ flask/bin/pip install flask-wtf
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$ flask/bin/pip install flask-babel
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$ flask/bin/pip install guess_language
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$ flask/bin/pip install flipflop
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$ flask/bin/pip install coverage
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```
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After that, let's create the basic structure for our application: `app` `app/static` `app/templates` `tmp`.
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1. `app` — where the application package is
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2. `static` — stores static files like images, javascripts, and css.
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3. `templates` — where templates will go.
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Then you can start with ``__init__.py`` which should put into app folder (file `app/__init__.py`):
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``` python
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from flask import Flask
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app = Flask(__name__)
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from app import views
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```
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The views are the handlers that response to requests from web browsers or other clients. Each view function is mapped to one or more request URLs.
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Let's see what a views function looks like (file `app/views.py`):
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``` python
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from flask import Flask
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app = Flask(__name__)
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from app import views
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```
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Finally we should create a script to starts up the web server with our application(file `run.py`):
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``` python
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#!flask/bin/python
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from app import app
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app.run(debug=True)
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```
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To indicating that is an executable file you need to run this in terminal:
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``` bash
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$ chmod a+x run.py
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```
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Now the file structure should look like:
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```
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microblog\
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flask\
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<virtual environment files>
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app\
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static\
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templates\
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__init__.py
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views.py
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tmp\
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run.py
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```
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Then start to write the template (file `app/templates/index.html`):
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``` html
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<html>
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<head>
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<title>{{ title }} - microblog</title>
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</head>
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<body>
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<h1>Hello, {{ user.nickname }}!</h1>
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</body>
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</html>
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```
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Now let's write the view function that uses this template (file `app/views.py`):
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``` python
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from flask import render_template
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from app import app
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@app.route('/')
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@app.route('/index')
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def index():
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user = {'nickname': 'ching'} # fake user
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return render_template('index.html',
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title='Home',
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user=user)
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```
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`render_template` function is what we import from Flask framework to render the template. It uses [Jinja2](http://jinja.pocoo.org/) templating engine.
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