递归获取类的属性和子属性

【问题标题】：Recursively Get Properties & Child Properties Of A Class递归获取类的属性和子属性
【发布时间】：2013-12-12 20:57:42
【问题描述】：

我正在做类似Recursively Get Properties & Child Properties Of An Object 的事情，但我想递归地使用反射来获取每个属性。我从Recursively Print the properties 得到了代码。

代码的问题是：它只下降了一层，我想知道如何使用反射自动获取所有属性？我刚刚编写了以下示例容器代码：

public class Container
{
    public Bottle MyBottle { get; set; }
    public List<Address> Addresses { get; set; }

    public Container()
    {
        Address a = new Address();
        a.AddressLine1 = "1 Main St";
        a.AddressLine2 = "2 Main St";
        Addresses = new List<Address>();
        Addresses.Add(a);

        MyBottle = new Bottle();
        MyBottle.BottleName = "Big bottle";
        MyBottle.BottageAge = 2;
    }
}

public class Bottle
{
    public string BottleName { get; set; }
    public int BottageAge { get; set; }
}

public class Address
{
    public string AddressLine1 { get; set; }
    public string AddressLine2 { get; set; }
    public List<SpecialFolder> SpecialFolders { get; set; }

    public Address()
    {
        SpecialFolders = new List<SpecialFolder>();
        SpecialFolder sf = new SpecialFolder();
        sf.TemplateFolder = Environment.SpecialFolder.Templates.ToString();
        sf.UserFolder = Environment.SpecialFolder.UserProfile.ToString();
        SpecialFolders.Add(sf);
    }
}

public class SpecialFolder
{
    public string TemplateFolder { get; set; }
    public string UserFolder { get; set; }
}

在 Main 方法中：

static void Main(string[] args)
{
    Container c = new Container();
    PrintProperties(c);
}
public static void PrintProperties(object obj)
{
    PrintProperties(obj, 0);
}
public static void PrintProperties(object obj, int indent)
{

    if (obj == null) return;
    string indentString = new string(' ', indent);
    Type objType = obj.GetType();
    PropertyInfo[] properties = objType.GetProperties();
    foreach (PropertyInfo property in properties)
    {
        object propValue = property.GetValue(obj, null);
        if (property.PropertyType.Assembly == objType.Assembly)
        {
            Console.WriteLine("{0}{1}:", indentString, property.Name);

            PrintProperties(propValue, indent + 2);
        }
        else
        {
            Console.WriteLine("{0}{1}: {2}", indentString, property.Name, propValue);
        }
    }
}

我希望得到：

MyBottle:
      BottleName: Big bottle
      BottageAge: 2
Addresses:
      AddressLine1: 1 Main St
      AddressLine2: 2 Main St
      SpecialFolders:
            TemplateFolder: Templates
            UserFolder: UserProfile

我现在得到的结果：

MyBottle:
  BottleName: Big bottle
  BottageAge: 2
Addresses: System.Collections.Generic.List`1[TreeViewReflectionExample.Address]

有人可以帮助我使用 PrintProperties 方法吗？非常感谢。

【问题讨论】：

    标签： c# reflection recursion


    【解决方案1】：

    您的代码有两个问题：

    1. 由于条件if (property.PropertyType.Assembly == objType.Assembly)，您将省略System.Collections，如List&lt;&gt;
    2. 你不会区别对待 propValue 是集合。因此它将打印List 属性，而不是其元素属性。

    例如，您可以将其更改为：

    public void PrintProperties(object obj, int indent)
{    
    if (obj == null) return;
    string indentString = new string(' ', indent);
    Type objType = obj.GetType();
    PropertyInfo[] properties = objType.GetProperties();
    foreach (PropertyInfo property in properties)
    {
        object propValue = property.GetValue(obj, null);
        var elems = propValue as IList;
        if (elems != null)
        {
            foreach (var item in elems)
            {
                PrintProperties(item, indent + 3);
            }
        }
        else
        {
            // This will not cut-off System.Collections because of the first check
            if (property.PropertyType.Assembly == objType.Assembly)
            {
                Console.WriteLine("{0}{1}:", indentString, property.Name);

                PrintProperties(propValue, indent + 2);
            }
            else
            {
                Console.WriteLine("{0}{1}: {2}", indentString, property.Name, propValue);
            }
        }
    }
}

    【讨论】：

    • 正是我想要的，不仅适用于这个例子，而且适用于我所拥有的所有其他案例
    • 这很有帮助。我做了一个小补充，以确保在调用 GetValue 之前可以读取该属性，以防止只写属性出现异常 - 只需将其包装为“if (property.CanRead) {...”。
    • C# 6 语法糖的好消息：if (propValue is IList elems) 工作并节省一行。
    • 我得到了System.Reflection.TargetParameterCountException这个设置：var person = new Person { Name = "Name", Vorname = "Firstname", Alter = 27, Adresse = new Adresse { Strasse = "Street", Ort = "Place" }, Hobbies = new List&lt;string&gt; { "Tennis", "Salsa", "blub" } };
    • 不错的代码，但它不打印内置类型列表，例如List&lt;int&gt;，还有Arrays
    【解决方案2】：

    您希望分别处理原始类型和字符串，并循环遍历可枚举而不是仅获取它们的 ToString() 值。所以你的代码可以更新为：

    public void PrintProperties(object obj, int indent)
{

    if (obj == null) return;
    string indentString = new string(' ', indent);
    Type objType = obj.GetType();
    PropertyInfo[] properties = objType.GetProperties();
    foreach (PropertyInfo property in properties)
    {   
        object propValue = property.GetValue(obj, null);
        if(property.PropertyType.IsPrimitive || property.PropertyType == typeof(string))
            Console.WriteLine("{0}{1}: {2}", indentString, property.Name, propValue);
        else if (typeof(IEnumerable).IsAssignableFrom(property.PropertyType))
        {
            Console.WriteLine("{0}{1}:", indentString, property.Name);
            IEnumerable enumerable = (IEnumerable)propValue;
            foreach(object child in enumerable)
                PrintProperties(child, indent + 2);
        }
        else 
        {
            Console.WriteLine("{0}{1}:", indentString, property.Name);
            PrintProperties(propValue, indent + 2);
        }
    }
}

    【讨论】：

    • 这段代码非常适合这个例子，当我添加更多的属性和类时，我得到了无限循环。我正在寻找一种获取所有属性的通用方法。
    • 经过一些小的修改后，这段代码对我有用。
    【解决方案3】：

    根据 Konrad Kokosa 的回答：

    private string ObjectToString(object obj, int indent = 0)
{
    if (obj is null)
    {
        return "";
    }

    var sb = new StringBuilder();
    string indentString = new string(' ', indent);
    Type objType = obj.GetType();

    foreach (PropertyInfo property in objType.GetProperties())
    {
        object propValue = property.GetValue(obj);
        var elems = propValue as IList;

        if (elems != null)
        {
            foreach (var item in elems)
            {
                sb.Append($"{indentString}- {property.Name}\n");
                sb.Append(ObjectToString(item, indent + 4));
            }
        }
        else if (property.Name != "ExtensionData")
        {
            sb.Append($"{indentString}- {property.Name}={propValue}\n");

            if (property.PropertyType.Assembly == objType.Assembly)
            {
                sb.Append(ObjectToString(propValue, indent + 4));
            }
        }
    }

    return sb.ToString();
}

    更新

    根据这个较早的问题编辑代码：TargetParameterCountException when enumerating through properties of string

    private string ObjectToString(object obj, int indent = 0)
    {
        var sb = new StringBuilder();

        if (obj != null)
        {
            string indentString = new string(' ', indent);

            if (obj is string)
            {
                sb.Append($"{indentString}- {obj}\n");
            }
            else if (obj is Array)
            {
                var elems = obj as IList;
                sb.Append($"{indentString}- [{elems.Count}] :\n");

                for (int i = 0; i < elems.Count; i++)
                {
                    sb.Append(ObjectToString(elems[i], indent + 4));
                }
            }
            else
            {
                Type objType = obj.GetType();
                PropertyInfo[] props = objType.GetProperties();

                foreach (PropertyInfo prop in props)
                {
                    if (prop.GetIndexParameters().Length == 0)
                    {
                        object propValue = prop.GetValue(obj);
                        var elems = propValue as IList;

                        if (elems != null)
                        {
                            foreach (var item in elems)
                            {
                                sb.Append($"{indentString}- {prop.Name} :\n");
                                sb.Append(ObjectToString(item, indent + 4));
                            }
                        }
                        else if (prop.Name != "ExtensionData")
                        {
                            sb.Append($"{indentString}- {prop.Name} = {propValue}\n");

                            if (prop.PropertyType.Assembly == objType.Assembly)
                            {
                                sb.Append(ObjectToString(propValue, indent + 4));
                            }
                        }
                    }
                    else
                    {
                        sb.Append($"{indentString}- {prop.Name} ({prop.PropertyType.Name}): <Indexed>\n");
                    }
                }
            }
        }

        return sb.ToString();
    }

    更新 2

    public static string ObjectToString(object obj, int indent = 0)
    {
        var sb = new StringBuilder();

        if (obj != null)
        {
            string indentString = new string(' ', indent);

            if (obj is string || obj.IsNumber())
            {
                sb.Append($"{indentString}- {obj}\n");
            }
            else if (obj.GetType().BaseType == typeof(Enum))
            {
                sb.Append($"{indentString}- {obj.ToString()}\n");
            }
            else if (obj is Array)
            {
                var elems = obj as IList;
                sb.Append($"{indentString}- [{elems.Count}] :\n");

                for (int i = 0; i < elems.Count; i++)
                {
                    sb.Append(ObjectToString(elems[i], indent + 4));
                }
            }
            else
            {
                Type objType = obj.GetType();
                PropertyInfo[] props = objType.GetProperties();

                foreach (PropertyInfo prop in props)
                {
                    if (prop.GetIndexParameters().Length == 0)
                    {
                        object propValue = prop.GetValue(obj);
                        var elems = propValue as IList;

                        if (elems != null)
                        {
                            foreach (var item in elems)
                            {
                                sb.Append($"{indentString}- {prop.Name} :\n");
                                sb.Append(ObjectToString(item, indent + 4));
                            }
                        }
                        else if (prop.Name != "ExtensionData")
                        {
                            sb.Append($"{indentString}- {prop.Name} = {propValue}\n");

                            if (prop.PropertyType.Assembly == objType.Assembly)
                            {
                                sb.Append(ObjectToString(propValue, indent + 4));
                            }
                        }
                    }
                    else if (objType.GetProperty("Item") != null)
                    {
                        int count = -1;

                        if (objType.GetProperty("Count") != null &&
                            objType.GetProperty("Count").PropertyType == typeof(int))
                        {
                            count = (int)objType.GetProperty("Count").GetValue(obj, null);
                        }

                        for (int i = 0; i < count; i++)
                        {
                            object val = prop.GetValue(obj, new object[] { i });
                            sb.Append(ObjectToString(val, indent + 4));
                        }
                    }
                }
            }
        }

        return sb.ToString();
    }

    public static bool IsNumber(this object value)
    {
        return value is sbyte
            || value is byte
            || value is short
            || value is ushort
            || value is int
            || value is uint
            || value is long
            || value is ulong
            || value is float
            || value is double
            || value is decimal;
    }

    【讨论】：

    • 很抱歉，并非所有属性都已打印出来
    【解决方案4】：

    我已经投入了大量时间来解决这个问题。正确转储所有属性类型需要许多特定于类型的格式。

    我可以建议您查看 github 上此文件中的 FormatValue 方法。将属性值写入字符串的主要逻辑是： https://github.com/thomasgalliker/ObjectDumper/blob/ada64c7e51fedf57731006959358aa890b5e4344/ObjectDumper/Internal/ObjectDumperCSharp.cs#L98

    您还可以将此代码用作 nuget 包： https://www.nuget.org/packages/ObjectDumper.NET

    【讨论】：

      【解决方案5】：

      它适用于所有情况，除了 propValue 是 string[]。您将在行中获得异常“参数计数不匹配”： object propValue = property.GetValue(obj, null);

      要解决此问题，您可以使用此代码稍作修正：

      private void PrintProperties(object obj, int indent)
    {
        if (obj == null) return;
        string indentString = new string(' ', indent);
        Type objType = obj.GetType();
        PropertyInfo[] properties = objType.GetProperties();
        foreach (PropertyInfo property in properties)
        {
            object propValue = property.GetValue(obj, null);

            var elems = propValue as IList;
            if ((elems != null) && !(elems is string[]) )
            {
                foreach (var item in elems)
                {
                    PrintProperties(item, indent + 3);
                }
            }
            else
            {
                // This will not cut-off System.Collections because of the first check
                if (property.PropertyType.Assembly == objType.Assembly)
                {
                    LogToWindow(String.Format("{0}{1}:", indentString, property.Name));
                    PrintProperties(propValue, indent + 2);
                }
                else
                {
                    if (propValue is string[])
                    {
                        var str = new StringBuilder();
                        foreach (string item in (string[])propValue)
                        {
                            str.AppendFormat("{0}; ", item);
                        }
                        propValue = str.ToString();
                        str.Clear();
                    }
                    LogToWindow(String.Format("{0}{1}: {2}", indentString, property.Name, propValue));
                }
            }
        }
    }

      【讨论】：

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