flask, SQLAlchemy, sqlite3 實現 RESTful API, 同時支持form操作。
前端與后台的交互都采用json數據格式,原生javascript實現的ajax。其技術要點如下
1.前端轉換:
1).json數據(來自后台) --> object對象(前端應用)
JSON.parse(xhr2.responseText)
2).FormData對象(前端生成) --> json數據(傳入后台)
// 輔助函數:FormData轉化為json
var convert_FormData_to_json = function (formData) {
var objData = {};
for (var entry of formData.entries()){
objData[entry[0]] = entry[1];
}
return JSON.stringify(objData);
};
2.后端轉換:
1).json數據(來自前端) --> 類似dict對象(后台應用)
request.json.get('title', task['title'])
2).dict對象(后台生成) --> json數據(傳入前端)
jsonify({'task': replace_id_to_uri(task)})
3.項目結構
/myapp
|----app.py
|----/templates
| |----index.html
4.兩個文件
1).app.py
from flask import Flask, jsonify, render_template
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True
db = SQLAlchemy(app)
# 定義ORM
class Todo(db.Model):
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String(80), unique=True)
description = db.Column(db.String(120), unique=True)
done = db.Column(db.Boolean)
def __init__(self, title, description, done):
self.title = title
self.description = description
self.done = done
def __repr__(self):
return '<Todo %r>' % self.title
# 創建表格、插入數據
@app.before_first_request
def create_db():
# Recreate database each time for demo
#db.drop_all()
db.create_all()
tasks = [Todo('Buy groceries', 'Milk, Cheese, Pizza, Fruit, Tylenol', False),
Todo('Learn Python', 'Need to find a good Python tutorial on the web', False),
Todo('Mow the lawn', 'Find out some tools', False)]
db.session.add_all(tasks)
db.session.commit()
# ==================================
# 下面路由至頁面
# ==================================
@app.route('/')
def index():
return render_template('index.html')
# ==================================
# 下面是RESTful api
# ==================================
# 輔助函數
from flask import url_for
def replace_id_to_uri(task):
return dict(uri = url_for('get_task', task_id=task.id, _external=True),
title = task.title,
description = task.description,
done = task.done)
# 查詢全部
@app.route('/todo/api/v1.0/tasks/', methods=['GET'])
def get_tasks():
tasks = Todo.query.all()
return jsonify({'tasks': list(map(replace_id_to_uri, tasks))})
# 查詢一個
from flask import abort
@app.route('/todo/api/v1.0/tasks/<int:task_id>', methods=['GET'])
def get_task(task_id):
task = Todo.query.filter_by(id=task_id).first()
if task is None:
abort(404)
return jsonify({'task': replace_id_to_uri(task)})
# 添加
from flask import request
@app.route('/todo/api/v1.0/tasks/', methods=['POST'])
def create_task():
# 沒有數據,或者數據缺少 title 項,返回 400,表示請求無效
if not request.json or not 'title' in request.json:
abort(400)
task = Todo(request.json['title'], request.json.get('description', ""), False)
db.session.add(task)
db.session.commit()
return jsonify({'task': replace_id_to_uri(task)}), 201
# 更新
@app.route('/todo/api/v1.0/tasks/<int:task_id>', methods=['PUT'])
def update_task(task_id):
task = Todo.query.filter_by(id=task_id).first()
if task is None:
abort(404)
if not request.json:
abort(400)
if 'title' in request.json and type(request.json['title']) != unicode:
abort(400)
if 'description' in request.json and type(request.json['description']) is not unicode:
abort(400)
if 'done' in request.json and type(request.json['done']) is not bool:
abort(400)
task['title'] = request.json.get('title', task['title'])
task['description'] = request.json.get('description', task['description'])
task['done'] = request.json.get('done', task['done'])
#db.session.update(task)
db.session.commit()
return jsonify({'task': replace_id_to_uri(task)})
# 刪除
@app.route('/todo/api/v1.0/tasks/<int:task_id>', methods=['DELETE'])
def delete_task(task_id):
task = Todo.query.filter_by(id=task_id).first()
if task is None:
abort(404)
db.session.delete(task)
db.session.commit()
return jsonify({'result': True})
# 定制404出錯頁面
@app.errorhandler(404)
def not_found(error):
return jsonify({'error': 'Not found'}), 404
if __name__ == '__main__':
app.run(debug=True)
2).index.html
<meta charset="utf-8"/>
<form enctype='application/json' method="post">
<label>任務標題:</label>
<input type="text" name="title"></br>
<label>任務描述:</label>
<input type="texteara" name="description"></br>
<button type="submit">添加任務</button>
</form>
<!-- 任務列表 -->
<ol id="container"></ol>
<script>
var container = document.getElementById('container');
// 輔助函數:將一條任務(task),放入form的下方容器的尾部
var add_child = function (task) {
var li = document.createElement("li");
li.innerText = task["title"] + " " + task["description"];
container.appendChild(li);
};
// 輔助函數:FormData轉化為json
var convert_FormData_to_json = function (formData) {
var objData = {};
for (var entry of formData.entries()){
objData[entry[0]] = entry[1];
}
return JSON.stringify(objData);
};
// 最初,ajax取全部任務,放入form的下方容器
window.onload = function () {
var xhr = new XMLHttpRequest();
xhr.open('GET', '/todo/api/v1.0/tasks/');
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.send();
xhr.addEventListener('loadend', function() {
if(xhr.status == 200){
var res = JSON.parse(xhr.responseText);
//console.log(res);
res["tasks"].map(add_child)
}
}, false);
};
</script>
<script>
var formobj = document.querySelector('form');
//var formobj = document.getElementByTag('form');
formobj.addEventListener('submit', function(event){
event.preventDefault();
var xhr2 = new XMLHttpRequest();
xhr2.open('POST', '/todo/api/v1.0/tasks/');
xhr2.setRequestHeader('Content-Type', 'application/json');
xhr2.send(convert_FormData_to_json(new FormData(formobj)));// 發送json數據!
xhr2.addEventListener('loadend', function() {
if(xhr2.status == 201){ // 201,去看app.py!!
var res2 = JSON.parse(xhr2.responseText);
[res2["task"]].map(add_child); // 這里也用map,沒別的目的,只想與前面的形式一致
}
}, false);
}, false);
</script>
5.效果圖
1). POST數據
2). Response數據
6.未完成的功能
1).更新任務(頁面操作)
2).刪除任務(頁面操作)
7.參考:
1).www.pythondoc.com/flask-restful/first.html