Bottle 中的 DRY 验证？

Question

我的 Bottle 应用程序还不是很干，这是一个测试用例：

from uuid import uuid4
from bottle import Bottle, response

foo_app = Bottle()

@foo_app.post('/foo')
def create():
    if not request.json:
        response.status = 400
        return {'error': 'ValidationError', 'error_message': 'Body required'}
    body = request.json
    body.update({'id': uuid4().get_hex())
    # persist to db
    # ORM might set 'id' on the Model layer rather than setting it here
    # ORM will validate, as will db, so wrap this in a try/catch
    response.status = 201
    return body

@foo_app.put('/foo/<id>')
def update(id):
    if not request.json:
        response.status = 400
        return {'error': 'ValidationError', 'error_message': 'Body required'}
    elif 'id' not in request.json:
        response.status = 400
        return {'error': 'ValidationError', 'error_message': '`id` required'}
    db = {} # should be actual db cursor or whatever
    if 'id' not in db:
        response.status = 404
        return {'error': 'Not Found',
                'error_message': 'Foo `id` "{id}" not found'.format(id)}
    body = request.json
    # persist to db, return updated object
    # another try/catch here in case of update error (from ORM and/or db)
    return body

解决这个问题的一种方法是拥有一个全局错误处理程序，并在所有地方引发错误。

另一种是使用装饰器，同样存在开销问题。

是否有更好的方法来完成每条路线的验证端？ - 我在想类似的东西：

foo_app.post('/foo', middleware=[HAS_BODY_F, ID_IN_DB_F])

Answer 1

这是我的 DRY 验证解决方案，以装饰器结尾：

from itertools import imap, ifilter    
from bottle import Bottle, request, response

app = Bottle()

middleware = lambda functions: lambda caller: lambda *args, **kwargs: next(
    ifilter(None, imap(lambda g: g(*args, **kwargs), functions)),
    caller(*args, **kwargs)
)


def has_body(*args, **kwargs):
    if not request.json:
        response.status = 400
        return {'error': 'ValidationError',
                'error_message': 'Body is required (and must be JSON).'}


def body_req(required):
    def inner(*args, **kwargs):
        intersection = required.intersection(set(request.json.keys()))
        if intersection != required:
            response.status = 400
            return {'error': 'ValidationError',
                   'error_message': 'Key(s): {} are not in JSON payload'.format(
                    ', '.join(imap(lambda key: "'{key}'".format(key=key),
                              required - intersection)))}

    return inner


@app.post('/foo')
@middleware([has_body, body_req({'id', 'f'})])
def get_foo():
    return {'foo': 'bar'}

Answer 2

最终找到 Bottle 的内置 "middleware" 称为 "plugins" (reference):

from bottle import Bottle, request, response

app = Bottle()


def has_body(f):
    def inner(*args, **kwargs):
        if request.json:
            return f(*args, **kwargs)

        response.status = 400
        return {'error': 'ValidationError',
                'error_message': 'Body is required (and must be JSON).'}
    return inner


def body_req(required):
    def body_req_middleware(f):
        def inner(*args, **kwargs):
            intersection = required.intersection(set(request.json.keys()))
            if intersection != required:
                response.status = 400
                return {'error': 'ValidationError',
                        'error_message': 'Key(s): {} are not in JSON payload'
                        ''.format(', '.join('{!r}'.format(k)
                                            for k in required - intersection))}
            return f(*args, **kwargs)
        return inner
    return body_req_middleware


@app.post('/foo', apply=(has_body, body_req({'id', 'f'})))
def get_foo():
    return {'foo': 'bar'}

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