使用 C# 比较嵌套对象的属性

Question

我有一个方法可以比较两个对象并返回所有不同属性名称的列表。

public static IList<string> GetDifferingProperties(object source, object target)
{
    var sourceType = source.GetType();
    var sourceProperties = sourceType.GetProperties();
    var targetType = target.GetType();
    var targetProperties = targetType.GetProperties();

    var properties = (from s in sourceProperties
                      from t in targetProperties
                      where s.Name == t.Name &&
                            s.PropertyType == t.PropertyType &&
                            s.GetValue(source,null) != t.GetValue(target,null)
                      select s.Name).ToList();
    return properties;
}

例如，如果我有两个类如下：

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; }
        }

我正在尝试比较以下两个员工实例：

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;


        var emp2Address = new Address();
        emp2Address.AddressLine1 = "Gates Foundation";
        emp2Address.AddressLine2 = "One Microsoft Way";
        emp2Address.City = "Redmond";
        emp2Address.State = "WA";
        emp2Address.Zip = "98052-6399";

        var emp2 = new Employee();
        emp2.FirstName = "Melinda";
        emp2.LastName = "Gates";
        emp2.EmployeeAddress = emp2Address;

因此，当我当前将这两个员工对象传递给我的 GetDifferingProperties 方法时，它返回 FirstName 和 EmployeeAddress，但它没有告诉我 EmployeeAddress 中的哪个确切属性（在本例中为 Address1）已更改。如何调整此方法以获得类似 EmployeeAddress.Address1 的内容？

Answer 1

这是因为您使用的是!=，对于对象，它测试对象的身份而不是其值。关键是使用递归来生成属性的列表。这将达到你想要的深度......

public static IList<string> GetDifferingProperties(object source, object target)
{
  var sourceType = source.GetType();
  var sourceProperties = sourceType.GetProperties();
  var targetType = target.GetType();
  var targetProperties = targetType.GetProperties();

  var result = new List<string>();

  foreach (var property in
      (from s in sourceProperties
       from t in targetProperties
       where s.Name == t.Name &&
       s.PropertyType == t.PropertyType &&
       !Equals(s.GetValue(source, null), t.GetValue(target, null))
       select new { Source = s, Target = t }))
  {
    // it's up to you to decide how primitive is primitive enough
    if (IsPrimitive(property.Source.PropertyType))
    {
      result.Add(property.Source.Name);
    }
    else
    {
      foreach (var subProperty in GetDifferingProperties(
          property.Source.GetValue(source, null),
          property.Target.GetValue(target, null)))
      {
        result.Add(property.Source.Name + "." + subProperty);
      }
    }
  }

  return result;
}

private static bool IsPrimitive(Type type)
{
  return type == typeof(string) || type == typeof(int);
}

Answer 2

我可以推荐使用http://comparenetobjects.codeplex.com/ 这有可能比较嵌套对象、枚举、IList 等。 该项目免费且易于使用（只需 1 个 .cs 文件）。此外，还可以获取不同的值，添加要忽略的属性等。

Answer 3

原则上，您需要在获得值后对要比较的两个对象使用您在GetDifferingProperties 中实现的技术（在查询中使用GetValue）。可能最直接的实现是使方法递归：

public static IEnumerable<string> GetDifferingProperties
    (object source, object target) {

  // Terminate recursion - equal objects don't have any differing properties
  if (source == target) return new List<string>();

  // Compare properties of two objects that are not equal
  var sourceProperties = source.GetType().GetProperties();
  var targetProperties = target.GetType().GetProperties();
  return
    from s in sourceProperties
    from t in targetProperties
    where s.Name == t.Name && s.PropertyType == t.PropertyType 
    let sVal = s.GetValue(source, null)
    let tVal = t.GetValue(target, null)

    // Instead of comparing the objects directly using '==', we run
    // the method recursively. If the two objects are equal, it returns
    // empty list immediately, otherwise it generates multiple properties
    from name in GetDifferingProperties(sVal, tVal)
    select name;
}

如果您想在实践中使用它，您可能需要跟踪如何访问该属性（此代码只为您提供了一个属性名称列表，而没有包含它们的对象的信息）。您可以将最后一行从 select name 更改为 select s.Name + "." + name，这将为您提供更完整的名称（例如，如果不同的属性是 Address 成员的 Name 属性，则为 Address.Name）。

Answer 4

一点：您的方法没有考虑 EmployeeAddress 属性中的实际差异。测试一下看看。

        emp2Address.AddressLine1 = emp1Address.AddressLine1;// "Gates Foundation";
        emp2Address.AddressLine2 = emp1Address.AddressLine2;// "One Microsoft Way";
        emp2Address.City = emp1Address.City;// "Redmond";
        emp2Address.State = emp1Address.State;// "WA";
        emp2Address.Zip = emp1Address.Zip;// "98052-6399";

程序仍将 EmployeeAddress 作为不匹配的属性返回。但是，如果您简单地设置 emp2.​​EmployeeAddress = emp1Address，您不会得到“不匹配”。

关于引用的一些东西...

无论如何，如果您想找到该对象的不同之处，您将不得不搜索该对象的不同之处。