【Flask 教學】建立你的第一個web app

Flask要如何建立一個網頁或是API呢？

其實不會太難，只要照著下面方法做，相信你很快就會了！

順便自己也做個筆記可以回顧一下。

如何透過Flask建立第一個web app?

首先建立一個hello.py

這是最一開始的寫法，算是預設參數

from flask import Flask
app = Flask(__name__)

內容目錄

網頁顯示hello字串，要怎麼操作呢？

Flask是透過裝飾器@app.route來定義url，可能第一次接觸不懂，沒關係。

多寫幾次就會懂意思了，可以參考下方寫法，()內的/代表根目錄，當然你也可以輸入其他路徑

簡單來說()裡面就是網站的路徑，可參考下方完整程式碼

最後我們直接在終端機輸入python3 hello.py，網站上輸入 http://127.0.0.1:5000，網頁將會顯示你的hello的字串

from flask import Flask

app = Flask(__name__)

@app.route("/")
def index():
	return 'hello'

if __name__ == '__main__':
	app.debug = True
	app.run()

你有可能會遇到下面的問題

from flask import Flask
ModuleNotFoundError: No module named 'flask'

# 只需要透過pip 安裝 flask就可行
$ pip3 install install flask
Defaulting to user installation because normal site-packages is not writeable
Collecting install
  Downloading install-1.3.4-py3-none-any.whl (3.1 kB)
Collecting flask
  Downloading Flask-2.0.2-py3-none-any.whl (95 kB)
     |████████████████████████████████| 95 kB 838 kB/s 
Collecting itsdangerous>=2.0
  Downloading itsdangerous-2.0.1-py3-none-any.whl (18 kB)
Collecting Werkzeug>=2.0
  Downloading Werkzeug-2.0.2-py3-none-any.whl (288 kB)
     |████████████████████████████████| 288 kB 1.6 MB/s 
Collecting Jinja2>=3.0
  Downloading Jinja2-3.0.2-py3-none-any.whl (133 kB)
     |████████████████████████████████| 133 kB 1.4 MB/s 
Collecting click>=7.1.2
  Downloading click-8.0.3-py3-none-any.whl (97 kB)
     |████████████████████████████████| 97 kB 962 kB/s 
Collecting MarkupSafe>=2.0
  Downloading MarkupSafe-2.0.1.tar.gz (18 kB)
Building wheels for collected packages: MarkupSafe
  Building wheel for MarkupSafe (setup.py) ... done
  Created wheel for MarkupSafe: filename=MarkupSafe-2.0.1-cp38-cp38-macosx_10_14_x86_64.whl size=18221 sha256=c966d157a4c10ced8b7af6a8af987d641b70f6744b9b9211464554eaa0b27df1
  Stored in directory: /Users/user/Library/Caches/pip/wheels/fd/ac/52/de22dc1b1f975843caa5d0e8c817618b816345617c1b01039b
Successfully built MarkupSafe
Installing collected packages: install, itsdangerous, Werkzeug, MarkupSafe, Jinja2, click, flask
  WARNING: The script flask is installed in '/Users/user/Library/Python/3.8/bin' which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
Successfully installed Jinja2-3.0.2 MarkupSafe-2.0.1 Werkzeug-2.0.2 click-8.0.3 flask-2.0.2 install-1.3.4 itsdangerous-2.0.1
WARNING: You are using pip version 20.2.3; however, version 21.3.1 is available.
You should consider upgrading via the '/Library/Developer/CommandLineTools/usr/bin/python3 -m pip install --upgrade pip' command.

文章內的程式碼都可以直接複製下來練習操作，或是直接套用到自己的專案都行！

多練習，對自已會有很大的幫助！

一回生二回熟，將所學習到內容變成自己的知識。

人就是要學習自己不會的事情，這樣才會不斷的成長、進步！

網頁顯示hello字串，要怎麼操作呢？

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