搜索类中所有字符串类型成员(包括搜索类类型中的属性)C# [英] Search all the string type member in a class(including searching the property in class type) C#

问题描述

我试图从一个类中找出所有字符串"类型的属性，但想知道如果这个类中有任何类类型属性，我该怎么做.

I tried to find out all the "string" type properties from a class, but wonder how can I do that if there is any class type property in this class.

以下代码显示了目标类和我的解决方案.

The following codes show the target class and my solution.

public class Credit_Card
{
    public string brand { get; set; }
    public string billing_phone { get; set; }
    public Expiration expiration { get; set; }
}

public class Expiration
{
    public string month { get; set; }
}


class program
{
    static void Main(string[] args)
    {
        foreach (PropertyInfo prop in typeof(Credit_Card).GetProperties())
        { 
            if(prop.PropertyType == typeof(string))
            {
                Console.WriteLine(prop.Name);              
            }
        }
        Console.ReadLine();
    }
}

我的Main"方法只能在 Credit_Card 类型中显示brand"和billing_phone"属性，而在过期类中缺少month"属性.

My "Main" method can only show "brand" and "billing_phone" properties in Credit_Card type, but missed "month" property in expiration class.

有什么办法可以在 Credit_Card 类中进行递归搜索?

Is there any way that I can do recursive search in Credit_Card class?

推荐答案

public static void Main (string[] args)
{
  foreach(PropertyInfo prop in GetStringProperties(typeof(Credit_Card)))
    Console.WriteLine(prop.Name);              
  Console.ReadLine();
}
public static IEnumerable<PropertyInfo> GetStringProperties(Type type)
{
  return GetStringProperties (type, new HashSet<Type> ());
}
public static IEnumerable<PropertyInfo> GetStringProperties(Type type, HashSet<Type> alreadySeen)
{
  foreach(var prop in type.GetProperties())
  {
    var propType = prop.PropertyType;
    if (propType == typeof(string))
      yield return prop;
    else if(alreadySeen.Add(propType))
      foreach(var indirectProp in GetStringProperties(propType, alreadySeen))
        yield return indirectProp;
  }
}

捕捉我们已经处理过的类型很重要，否则你可以很容易地进入无限循环，因为这采用递归方法，它会因 StackOverflowException 而崩溃，而不仅仅是挂起永远像迭代等价物一样.(唯一比抛出异常更糟糕的情况是不抛出异常).

It's important to catch types we've already processed, or you can easily get into an infinite loop with the small mercy that since this takes a recursive approach it crashes with a StackOverflowException rather than just hanging forever like the iterative equivalent would. (Another case of the only thing worse than throwing an exception is no throwing an exception).

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