scrapy中start_requests指定回调函数为何没有调用

###### 问题遇到的现象和发生背景
ef start_requests(self):
        login_url = 'https://antispider7.scrape.center/api/login'
        header = {
            'Content-Type': 'application/json;charset=UTF-8',
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36',
        }
        param = {
            'password': 'admin',
            'username': 'admin',
        }
        yield scrapy.Request(url=login_url, headers=header, body=json.dumps(param), method='POST', callback=self.login_callback)

    def login_callback(self, response):
        print(response.text)
        jwt = 'jwt ' + json.loads(response.text)['token']
        header = {
            'Authorization': jwt
        }
        for page in range(1, 3):
            url = 'https://antispider7.scrape.center/api/book/?limit=18&offset=%s' % ((page-1) * 18)
            yield scrapy.Request(url=url, headers=header, callback=self.parse_list)

    def parse_list(self, response):
        print(response.text)
        results = json.loads(response.text)
        for result in results['results']:
            book_id = result['id']
            title = result['name']
            score = result['score']
            author = ''.join(result['author']).replace('\n', '').replace('\t', '').replace('\r', '')
            outurl = result['cover']
            print(book_id, title, score, author, outurl)

问题相关代码，请勿粘贴截图

我需要先登录获取token加入到header中，因此我选择使用startr_requests来完成，但是yield之后始终没有任何回调函数捕捉到，请问可能的原因是什么？

改成这样试试

        yield scrapy.Request(url=login_url, headers=header, body=json.dumps(param), method='POST', callback=lambda x,s=self: s.login_callback(x))

你题目的解答代码如下：

    def start_requests(self):
        login_url = 'https://antispider7.scrape.center/api/login'
        header = {
            'Content-Type': 'application/json;charset=UTF-8',
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36',
        }
        param = {
            'password': 'admin',
            'username': 'admin',
        }
        yield scrapy.Request(url=login_url, headers=header, body=json.dumps(param), method='POST', callback=lambda x,s=self: s.login_callback(x))
 
    def login_callback(self, response):
        print(response.text)
        jwt = 'jwt ' + json.loads(response.text)['token']
        header = {
            'Authorization': jwt
        }
        for page in range(1, 3):
            url = 'https://antispider7.scrape.center/api/book/?limit=18&offset=%s' % ((page-1) * 18)
            yield scrapy.Request(url=url, headers=header, callback=lambda x,s=self: s.parse_list(x))
 
    def parse_list(self, response):
        print(response.text)
        results = json.loads(response.text)
        for result in results['results']:
            book_id = result['id']
            title = result['name']
            score = result['score']
            author = ''.join(result['author']).replace('\n', '').replace('\t', '').replace('\r', '')
            outurl = result['cover']
            print(book_id, title, score, author, outurl)

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