Python Falcon 后缀的响应器

为了理解后缀响应器的概念和需要，让我们定义一个 StudentResource 类。它由一个 on_get() 响应器组成，该响应器将学生的 dict 对象列表转换为JSON，并作为其响应返回。

我们还可以添加 on_post() 响应器，它从传入的请求中读取数据并在列表中添加一个新的 dict 对象。

import falcon
import json
from waitress import serve
students = [
   {"id": 1, "name": "Ravi", "percent": 75.50},
   {"id": 2, "name": "Mona", "percent": 80.00},
   {"id": 3, "name": "Mathews", "percent": 65.25},
]
class StudentResource:
   def on_get(self, req, resp):
      resp.text = json.dumps(students)
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_JSON
   def on_post(self, req, resp):
      student = json.load(req.bounded_stream)
      students.append(student)
      resp.text = "Student added successfully."
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_TEXT

使用Falcon’s App对象的 add_route() 函数，我们添加 /students 路线。

app = falcon.App()
app.add_route("/students", StudentResource())

启动服务器后，我们可以从HTTPie命令行测试GET和POST请求—-。

http GET localhost:8000/students
HTTP/1.1 200 OK
Content-Length: 187
Content-Type: application/json
Date: Mon, 18 Apr 2022 06:21:02 GMT
Server: waitress
[
   {
      "id": 1,
      "name": "Ravi",
      "percent": 75.5
   },
   {
      "id": 2,
      "name": "Mona",
      "percent": 80.0
   },
   {
      "id": 3,
      "name": "Mathews",
      "percent": 65.25
   }
]
http POST localhost:8000/students id=4 name="Prachi"
percent=59.90
HTTP/1.1 200 OK
Content-Length: 27
Content-Type: text/plain; charset=utf-8
Date: Mon, 18 Apr 2022 06:20:51 GMT
Server: waitress
Student added successfully.

再次调用 on_get() 确认增加了新的学生资源。

http GET localhost:8000/students
HTTP/1.1 200 OK
Content-Length: 187
Content-Type: application/json
Date: Mon, 18 Apr 2022 06:21:02 GMT
Server: waitress
[
   {
      "id": 1,
      "name": "Ravi",
      "percent": 75.5
   },
   {
      "id": 2,
      "name": "Mona",
      "percent": 80.0
   },
   {
      "id": 3,
      "name": "Mathews",
      "percent": 65.25
   },
   {
      "id": "4",
      "name": "Prachi",
      "percent": "59.90"
   }
]

在这个阶段，我们希望在 StudentResource 类中有一个GET应答方法，从URL中读取id参数，并从列表中检索出一个相应的 dict 对象。

换句话说，格式为/student/{id}的URL应该与资源类中的GET方法相关。但显然，一个类不能有两个同名的方法。因此，我们定义在 add_route() 方法中使用后缀参数来区分 on_get() 响应器的两个定义。

通过指定 后缀=’student ‘，一个带有id参数的路由被添加到应用程序对象中。

app.add_route("/students/{id:int}", StudentResource(), suffix='student')

我们现在可以添加另一个定义 on_get( )方法的后缀，这样这个响应者的名字就是 on_get_student() ，如下所示

def on_get_student(self, req, resp, id):
   resp.text = json.dumps(students[id-1])
   resp.status = falcon.HTTP_OK
   resp.content_type = falcon.MEDIA_JSON

在添加新的路由和 on_get_student( )响应器后，启动 Waitress 服务器，并测试这个URL，如下所示

http GET localhost:8000/students/2
HTTP/1.1 200 OK
Content-Length: 42
Content-Type: application/json
Date: Mon, 18 Apr 2022 06:21:05 GMTy
Server: waitress
{
   "id": 2,
   "name": "Mona",
   "percent": 80.0
}

请注意，当客户端用适当的请求头请求 /students/{id:int} 这个URL路由时， on_put() 响应器（用于更新资源）和 on_delete() 响应器（用于删除资源）也将被调用。

我们已经添加了这个以student为后缀的路由。因此， on_put_student() 方法将路径参数解析为一个整数变量。具有给定id的项目的JSON表示被获取，并以PUT请求中提供的数据进行更新。

def on_put_student(self, req, resp, id):
   student=students[id-1]
   data = json.load(req.bounded_stream)

   student.update(data)
   resp.text = json.dumps(student)
   resp.status = falcon.HTTP_OK
   resp.content_type = falcon.MEDIA_JSON

on_delete_student() 响应者只是删除了DELETE请求中指定的id的项目。剩下的资源列表将被返回。

def on_delete_student(self, req, resp, id):
   students.pop(id-1)
   resp.text = json.dumps(students)
   resp.status = falcon.HTTP_OK
   resp.content_type = falcon.MEDIA_JSON

我们可以用 HTTPie 命令测试API的PUT和DELETE操作—-。

http PUT localhost:8000/students/2 id=3 name="Mathews"
percent=55
HTTP/1.1 200 OK
Content-Length: 46
Content-Type: application/json
Date: Sat, 18 Apr 2022 10:13:00 GMT
Server: waitress
{
   "id": "3",
   "name": "Mathews",
   "percent": "55"
}
http DELETE localhost:8000/students/2
HTTP/1.1 200 OK
Content-Length: 92
Content-Type: application/json
Date: Sat, 18 Apr 2022 10:18:00 GMT
Server: waitress
[
   {
      "id": 1,
      "name": "Ravi",
      "percent": 75.5
   },
   {
      "id": 3,
      "name": "Mathews",
      "percent": 65.25
   }
]

这个API（ studentapi.py ）的完整代码如下

import falcon
import json
from waitress import serve
students = [
   {"id": 1, "name": "Ravi", "percent": 75.50},
   {"id": 2, "name": "Mona", "percent": 80.00},
   {"id": 3, "name": "Mathews", "percent": 65.25},
]
class StudentResource:
   def on_get(self, req, resp):
      resp.text = json.dumps(students)
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_JSON
   def on_post(self, req, resp):
      student = json.load(req.bounded_stream)
      students.append(student)
      resp.text = "Student added successfully."
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_TEXT
   def on_get_student(self, req, resp, id):
      resp.text = json.dumps(students[id-1])
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_JSON
   def on_put_student(self, req, resp, id):
      student=students[id-1]
      data = json.load(req.bounded_stream)

      student.update(data)

      resp.text = json.dumps(student)
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_JSON
   def on_delete_student(self, req, resp, id):
      students.pop(id-1)
      print (students)
      resp.text = json.dumps(students)
      resp.status = falcon.HTTP_OK
      resp.content_type = falcon.MEDIA_JSON
app = falcon.App()
app.add_route("/students", StudentResource())
app.add_route("/students/{id:int}", StudentResource(), suffix='student')
if __name__ == '__main__':
   serve(app, host='0.0.0.0', port=8000)