Flask SQLite - tw511教學網

Python擁有對SQlite的內建支援。 SQlite3模組隨附Python發行版。有關在Python中使用SQLite資料庫的詳細教學，請參閱此連結。在本節中，我們將看到Flask應用程式如何與SQLite進行互動。

建立一個SQLite資料庫‘database.db’並在其中建立一個student表。

import sqlite3

conn = sqlite3.connect('database.db')
print "Opened database successfully";

conn.execute('CREATE TABLE students (name TEXT, addr TEXT, city TEXT, pin TEXT)')
print "Table created successfully";
conn.close()

Flask應用程式有三個檢視函式。

第一個new_student()函式係結到URL規則(‘/addnew’)。它呈現包含學生資訊表單的HTML檔案。

@app.route('/enternew')
def new_student():
    return render_template('student.html')

‘student.html’的HTML指令碼如下 -

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Flask範例</title>
</head>
   <body>

    <form action = "{{ url_for('addrec') }}" method = "POST">
         <h3>學生資訊</h3>
         姓名<br>
         <input type = "text" name = "nm" /></br>

         地址<br>
         <textarea name = "add" /><br>

         城市<br>
         <input type = "text" name = "city" /><br>

         郵編<br>
         <input type = "text" name = "pin" /><br>
         <input type = "submit" value = "提交" /><br>
      </form>

   </body>
</html>

可以看出，表單資料發布到系結addrec()函式，對應於URL => ‘/addrec’ 。

這個addrec()函式通過POST方法檢索表單的資料並插入到學生表中。與插入操作中的成功或錯誤相對應的訊息呈現為’result.html’。

@app.route('/addrec',methods = ['POST', 'GET'])
def addrec():
    if request.method == 'POST':
       try:
          nm = request.form['nm']
          addr = request.form['add']
          city = request.form['city']
          pin = request.form['pin']

          with sql.connect("database.db") as con:
             cur = con.cursor()
             cur.execute("INSERT INTO students (name,addr,city,pin) 
               VALUES (?,?,?,?)",(nm,addr,city,pin) )

             con.commit()
             msg = "Record successfully added"
       except:
          con.rollback()
          msg = "error in insert operation"

       finally:
          return render_template("result.html",msg = msg)
          con.close()

result.html 的HTML指令碼包含顯示插入操作結果的跳脫語句{{msg}}。

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Flask範例</title>
</head>
   <body>

      操作結果 : {{ msg }}
      <h2><a href = "/">返回主頁</a></h2>

   </body>
</html>

該應用程式包含由URL => ‘/list’表示的另一個list()函式。它將「行」填充為包含學生表中所有記錄的MultiDict物件。這個物件傳遞到 list.html 模板。

@app.route('/list')
def list():
    con = sql.connect("database.db")
    con.row_factory = sql.Row

    cur = con.cursor()
    cur.execute("select * from students")

    rows = cur.fetchall(); 
    return render_template("list.html",rows = rows)

這個list.html是一個模板，它遍歷行集合併在HTML表格中呈現資料。

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Flask範例</title>
</head>
   <body>

      <table border = 1>
         <thead>
            <td>改名</td>
            <td>地址</td>
            <td>城市</td>
            <td>編碼</td>
         </thead>

         {% for row in rows %}
            <tr>
               <td>{{row["name"]}}</td>
               <td>{{row["addr"]}}</td>
               <td>{{row["city"]}}</td>
               <td>{{row['pin']}}</td>    
            </tr>
         {% endfor %}
      </table>

      <a href = "/">返回主頁</a>

   </body>
</html>

最後，URL => ‘/‘規則呈現一個’home.html’作為應用程式的入口點。

@app.route('/')
def home():
    return render_template('home.html')

這裡是Flask-SQLite應用程式的完整程式碼。

from flask import Flask, render_template, request
import sqlite3 as sql
import sqlite3
app = Flask(__name__)

@app.route('/')
def home():
    return render_template('home.html')


@app.route('/enternew')
def new_student():
    return render_template('student.html')

@app.route('/addrec',methods = ['POST', 'GET'])
def addrec():
    if request.method == 'POST':
       try:
          nm = request.form['nm']
          addr = request.form['add']
          city = request.form['city']
          pin = request.form['pin']

          with sql.connect("database.db") as con:
             cur = con.cursor()

             cur.execute("INSERT INTO students (name,addr,city,pin) VALUES (?,?,?,?)",(nm,addr,city,pin) )

             con.commit()
             msg = "Record successfully added"
       except:
          con.rollback()
          msg = "error in insert operation"

       finally:
          return render_template("result.html",msg = msg)
          con.close()

@app.route('/list')
def list():
    con = sql.connect("database.db")
    con.row_factory = sql.Row

    cur = con.cursor()
    cur.execute("select * from students")

    rows = cur.fetchall();
    return render_template("list.html",rows = rows)

@app.route('/init')
def init():
    conn = sqlite3.connect('database.db')
    print ("Opened database successfully")

    conn.execute('CREATE TABLE students (name TEXT, addr TEXT, city TEXT, pin TEXT)')
    print ("Table created successfully")
    conn.close()
    return None

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

從Python shell執行此指令碼，並在開發伺服器開始執行時執行。存取:http:// localhost:5000/ 在瀏覽器中顯示一個這樣的簡單選單 -

點選「新增學生資訊」 連結開啟新增學生資訊表單。

填寫表單並提交。底層函式將該記錄插入到學生表中。

返回主頁並點選「顯示列表」連結，將顯示顯示樣本資料的表格。