Python Flask：TypeError: unsupported operand type(s) for -: ‘str‘ and ‘int‘

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背景

项目中常见的分页功能，代码如下：

# 收藏列表
@blog_base_blueprint.route('/resource_like_list/<int:user_id>', methods=['POST'])
def getResourceLikeList(user_id):page_size = request.form.get('page_size', default=2)page_num = request.form.get('page_num', default=1)offset = (page_num - 1) * page_sizeprint(offset)print(page_num)print(page_size)logs = models.ResourceLikeLog.query.filter_by(user_id=user_id).filter_by(delete_flag=0).order_by(models.ResourceLikeLog.id.desc()).offset(offset).limit(page_size)return jsonify({'code': 1,'msg': '成功','data': [log.to_format() for log in logs]})

项目启动时可以使用，但是我在postman中传了page_num的参数，然后就报异常TypeError: unsupported operand type(s) for -: 'str' and 'int';
根据异常信息，是类型的的问题，需要将str转为int，这里还是很好处理的，在接受参数的时候，处理一下就可以喽。

request.form.get（）

点到源码，

def get(self, key, default=None, type=None):"""Return the default value if the requested data doesn't exist.If `type` is provided and is a callable it should convert the value,return it or raise a :exc:`ValueError` if that is not possible.  Inthis case the function will return the default as if the value was not:param key: The key to be looked up.:param default: The default value to be returned if the key can'tbe looked up.  If not further specified `None` isreturned.:param type: A callable that is used to cast the value in the:class:`MultiDict`.  If a :exc:`ValueError` is raisedby this callable the default value is returned."""try:rv = self[key]except KeyError:return defaultif type is not None:try:rv = type(rv)except ValueError:rv = defaultreturn rv

能看到这个方法的参数：有默认值，还有一个参数类型的参数，用来强制转换参数类型，调整代码为:

    page_size = request.form.get('page_size', default=2, type=int)page_num = request.form.get('page_num', default=1, type=int)

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