Question

我尝试在format（）函数中将多个参数作为dict发送，但我收到此错误：

import UIKit

class tableOutlineViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet weak var tableView: UITableView!


    var names = ["Max", "Bill", "Reagan", "Mikayla", "Jessie", "Sierra", "Jeff", "Erik", "Landon"]
    var numbers = ["35", "33", "29", "27", "25", "23", "19", "15", "11"]
    var photo = [UIImage(named: "Person1"), UIImage(named: "Person2"), UIImage(named: "Groceries"), UIImage(named: "Person3"), UIImage(named: "Person4"), UIImage(named: "Person5"), UIImage(named: "Person6"), UIImage(named: "Person7")]


    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return names.count
    }

    public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = self.tableView.dequeueReusableCell(withIdentifier: "CustomCell") as! CustomCell

        cell.images.image = photo[indexPath.row]
        cell.name.text = names[indexPath.row]
        cell.number.text = numbers[indexPath.row]


        return cell
    }

}

这是我的代码：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in open_query
KeyError: 'asset_name'

参数可以是以下之一：

def open_query(query_file,parameters):
    fd = open(query_file, 'r')
    query = fd.read()
    query = query.format(parameters)
    fd.close()
    return query

或

parameters = {'date_':my_date,'instrument':'BTC_ETH'}

我该如何解决这个问题？

Answer 1

您想要对字典进行双重处理，但您还需要为模板字符串指定值。

举个例子，

>>> params={"a":1, "foo":"bar"}
>>> "There is {a} {foo}".format(**params)
'There is 1 bar'

如果需要，您还可以查看Jinja2 / Mako模板。

Answer 2

正如 cricket_007 写的那样，您应该使用**解包参数dict

query.format(**parameters)

但是你的其他输入仍然会失败

parameters = {'date_':my_date,'instrument':'BTC_ETH'}
query = "{assent_name}"
query.format(**parameters)

KeyError：'assent_name'

您应该考虑这个案例并解决它。也许使用默认字典

from collections import defaultdict 
paramerters = defaultdict(lambda : "N/A")
print("{assent_name}".format_map(paramerters))

无法以通用方式发送功能输入

2 个答案: