使用反射获取嵌套对象属性值

Question

我有以下两个类：

public class Address
{
    public string AddressLine1 { get; set; }
    public string AddressLine2 { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string Zip { get; set; }
}

public class Employee
{
    public string FirstName { get; set; }
    public string MiddleName { get; set; }
    public string LastName { get; set; }
    public Address EmployeeAddress { get; set; }
}

我有一个员工类的实例如下：

    var emp1Address = new Address();
    emp1Address.AddressLine1 = "Microsoft Corporation";
    emp1Address.AddressLine2 = "One Microsoft Way";
    emp1Address.City = "Redmond";
    emp1Address.State = "WA";
    emp1Address.Zip = "98052-6399";

    var emp1 = new Employee();
    emp1.FirstName = "Bill";
    emp1.LastName = "Gates";
    emp1.EmployeeAddress = emp1Address;

我有一个根据属性名获取属性值的方法，如下：

public object GetPropertyValue(object obj ,string propertyName)
{
    var objType = obj.GetType();
    var prop = objType.GetProperty(propertyName);

    return prop.GetValue(obj, null);
}

上述方法适用于像GetPropertyValue(emp1, "FirstName") 这样的调用，但如果我尝试GetPropertyValue(emp1, "Address.AddressLine1") 它会抛出异常，因为objType.GetProperty(propertyName); 无法定位嵌套对象属性值。有没有办法解决这个问题？

Answer 1

public object GetPropertyValue(object obj, string propertyName)
{
    foreach (var prop in propertyName.Split('.').Select(s => obj.GetType().GetProperty(s)))
       obj = prop.GetValue(obj, null);

    return obj;
}

谢谢，我来这里是为了寻找相同问题的答案。我最终修改了您的原始方法以支持嵌套属性。这应该比必须进行嵌套方法调用更健壮，因为嵌套方法调用最终可能会导致超过 2 个嵌套级别变得繁琐。

Answer 2

var address = GetPropertyValue(GetPropertyValue(emp1, "Address"), "AddressLine1");

Object Employee 没有一个名为“Address.AddressLine1”的属性，它有一个名为“Address”的属性，它本身也有一个名为“AddressLine1”的属性。

Answer 3

这适用于无限数量的嵌套属性。

public object GetPropertyValue(object obj, string propertyName)
{
    var _propertyNames = propertyName.Split('.');

    for (var i = 0; i < _propertyNames.Length; i++)
    {
        if (obj != null)
        {
            var _propertyInfo = obj.GetType().GetProperty(_propertyNames[i]);
            if (_propertyInfo != null)
                obj = _propertyInfo.GetValue(obj);
            else
                obj = null;
        }
    }

    return obj;
}

用法：

GetPropertyValue(_employee, "Firstname");
GetPropertyValue(_employee, "Address.State");
GetPropertyValue(_employee, "Address.Country.Name");

Answer 4

我使用这种方法从属性（无限数量的嵌套属性）中获取值，如下所示：

“财产”

“地址.街道”

“Address.Country.Name”

    public static object GetPropertyValue(object src, string propName)
    {
        if (src == null) throw new ArgumentException("Value cannot be null.", "src");
        if (propName == null) throw new ArgumentException("Value cannot be null.", "propName");

        if(propName.Contains("."))//complex type nested
        {
            var temp = propName.Split(new char[] { '.' }, 2);
            return GetPropertyValue(GetPropertyValue(src, temp[0]), temp[1]);
        }
        else
        {
            var prop = src.GetType().GetProperty(propName);
            return prop != null ? prop.GetValue(src, null) : null;
        }
    }

这里是小提琴：https://dotnetfiddle.net/PvKRH0

Answer 5

获取 Nest 属性，例如 Developer.Project.Name

private static System.Reflection.PropertyInfo GetProperty(object t, string PropertName)
            {
                if (t.GetType().GetProperties().Count(p => p.Name == PropertName.Split('.')[0]) == 0)
                    throw new ArgumentNullException(string.Format("Property {0}, is not exists in object {1}", PropertName, t.ToString()));
                if (PropertName.Split('.').Length == 1)
                    return t.GetType().GetProperty(PropertName);
                else
                    return GetProperty(t.GetType().GetProperty(PropertName.Split('.')[0]).GetValue(t, null), PropertName.Split('.')[1]);
            }

Answer 6

还有另一种变体。短小精悍，支持任意深度的属性，处理空值和无效属性：

public static object GetPropertyVal(this object obj, string name) {
    if (obj == null)
        return null;

    var parts = name.Split(new[] { '.' }, 2);
    var prop = obj.GetType().GetProperty(parts[0]);
    if (prop == null)
        throw new ArgumentException($"{parts[0]} is not a property of {obj.GetType().FullName}.");

    var val = prop.GetValue(obj);
    return (parts.Length == 1) ? val : val.GetPropertyVal(parts[1]);
}

Answer 7

我为这个提议做了一个类型的扩展方法：

public static class TypeExtensions
{
    public static PropertyInfo GetSubProperty(this Type type, string treeProperty, object givenValue)
    {
        var properties = treeProperty.Split('.');
        var value = givenValue;

        foreach (var property in properties.Take(properties.Length - 1))
        {
            value = value.GetType().GetProperty(property).GetValue(value);

            if (value == null)
            {
                return null;
            }
        }

        return value.GetType().GetProperty(properties[properties.Length - 1]);
    }

    public static object GetSubPropertyValue(this Type type, string treeProperty, object givenValue)
    {
        var properties = treeProperty.Split('.');
        return properties.Aggregate(givenValue, (current, property) => current.GetType().GetProperty(property).GetValue(current));
    }
}

Answer 8

上面的修改版本，用于获取多级嵌套属性

private static System.Reflection.PropertyInfo GetProperty(object t, string PropertName, out object Value)
        {
            Value = "";
            var v = t.GetType().GetProperties();
            if (t.GetType().GetProperties().Count(p => p.Name == PropertName.Split('.')[0]) == 0)
                //throw new ArgumentNullException(string.Format("Property {0}, is not exists in object {1}", PropertName, t.ToString()));
                return null;
            if (PropertName.Split('.').Length == 1)
            {
                var Value1 = t.GetType().GetProperty(PropertName).GetValue(t, null);
                Value = Value1;//.ToString();
                return t.GetType().GetProperty(PropertName);
            }
            else
            {
                //return GetProperty(t.GetType().GetProperty(PropertName.Split('.')[0]).GetValue(t, null), PropertName.Split('.')[1], out Value);
                return GetProperty(t.GetType().GetProperty(PropertName.Split('.')[0]).GetValue(t, null), PropertName.Substring(PropertName.IndexOf('.') + 1, PropertName.Length - PropertName.IndexOf('.') - 1), out Value);
            }
        }

Answer 9

这适用于 1 级和 2 级对象属性，例如Firstname 和 Address.AddressLine1

public object GetPropertyValue(object obj, string propertyName)
{
    object targetObject = obj;
    string targetPropertyName = propertyName;

    if (propertyName.Contains('.'))
    {
        string[] split = propertyName.Split('.');
        targetObject = obj.GetType().GetProperty(split[0]).GetValue(obj, null);
        targetPropertyName = split[1];
    }

    return targetObject.GetType().GetProperty(targetPropertyName).GetValue(targetObject, null);
}

Answer 10

我在静态类中的结构类型有问题，所以我必须使用这个方法GetNestedType，如果你知道属性名称，这是示例代码，如果你想getAll，你可以使用GetNestedTypes

此示例中的ExpandoObject 仅用于动态添加属性和值

private void ExtractValuesFromAppconstants(string keyName)
        {
            Type type = typeof(YourClass);
            var examination = type.GetNestedType(keyName);
            if (examination != null)
            {    
                var innerTypes = examination.GetNestedTypes();
                foreach (var innerType in innerTypes)
                {
                    Console.Writeline($"{innerType.Name}")
                }
            }
        }

Answer 11

递归方法，一行一行……

object GetPropertyValue(object obj, string propertyName)
{
    return propertyName.Contains(".") ? GetPropertyValue(obj.GetType().GetProperty(propertyName.Split(".").First()).GetValue(obj), string.Join(".", propertyName.Split(".").Skip(1))) : obj != null ? obj.GetType().GetProperty(propertyName).GetValue(obj) : null;
}