我有两个相同类型的对象，我想遍历每个对象的公共属性并提醒用户哪些属性不匹配。
是否可以在不知道对象包含哪些属性的情况下执行此操作？
【问题讨论】：
Compare NET Objects可以帮到你！
CompareLogic logic = new CompareLogic();
var compare = logic.Compare(obj1, obj2);
comparacao.Differences.ForEach(diff => Debug.Write(diff.PropertyName));
// Or formatted summary
Debug.Write(comparacao.DifferencesString);
【讨论】：
正如许多人提到的递归方法，这是您可以将搜索到的名称和属性传递给的函数：
public static void loopAttributes(PropertyInfo prop, string targetAttribute, object tempObject)
{
foreach (PropertyInfo nestedProp in prop.PropertyType.GetProperties())
{
if(nestedProp.Name == targetAttribute)
{
//found the matching attribute
}
loopAttributes(nestedProp, targetAttribute, prop.GetValue(tempObject);
}
}
//in the main function
foreach (PropertyInfo prop in rootObject.GetType().GetProperties())
{
loopAttributes(prop, targetAttribute, rootObject);
}
【讨论】：
使用 LINQ 和反射比较两个相同类型的对象。 注意！这基本上是对 Jon Skeet 解决方案的重写，但具有更紧凑和现代的语法。它还应该生成更有效的 IL。
它是这样的：
public bool ReflectiveEquals(LocalHdTicket serverTicket, LocalHdTicket localTicket)
{
if (serverTicket == null && localTicket == null) return true;
if (serverTicket == null || localTicket == null) return false;
var firstType = serverTicket.GetType();
// Handle type mismatch anyway you please:
if(localTicket.GetType() != firstType) throw new Exception("Trying to compare two different object types!");
return !(from propertyInfo in firstType.GetProperties()
where propertyInfo.CanRead
let serverValue = propertyInfo.GetValue(serverTicket, null)
let localValue = propertyInfo.GetValue(localTicket, null)
where !Equals(serverValue, localValue)
select serverValue).Any();
}
【讨论】：
where !Equals(serverValue, localValue) 行替换为firstType.IsValueType ? !Equals(serverValue, localValue) : !ReflectiveEquals(serverValue, localValue)
真正的问题：如何获得两组的差异？
我发现最快的方法是先将集合转换为字典，然后再进行 diff 'em。这是一个通用的方法：
static IEnumerable<T> DictionaryDiff<K, T>(Dictionary<K, T> d1, Dictionary<K, T> d2)
{
return from x in d1 where !d2.ContainsKey(x.Key) select x.Value;
}
然后你可以这样做：
static public IEnumerable<PropertyInfo> PropertyDiff(Type t1, Type t2)
{
var d1 = t1.GetProperties().ToDictionary(x => x.Name);
var d2 = t2.GetProperties().ToDictionary(x => x.Name);
return DictionaryDiff(d1, d2);
}
【讨论】：
当然你可以用反射。这是从给定类型中获取属性的代码。
var info = typeof(SomeType).GetProperties();
如果您能提供更多关于您所比较的属性的信息，我们可以汇总一个基本的差异算法。此实例代码将在名称上有所不同
public bool AreDifferent(Type t1, Type t2) {
var list1 = t1.GetProperties().OrderBy(x => x.Name).Select(x => x.Name);
var list2 = t2.GetProperties().OrderBy(x => x.Name).Select(x => x.Name);
return list1.SequenceEqual(list2);
}
【讨论】：
.Select(...)
是的，使用反射 - 假设每个属性类型都适当地实现了 Equals。另一种方法是对除某些已知类型以外的所有类型递归使用ReflectiveEquals，但这会变得很棘手。
public bool ReflectiveEquals(object first, object second)
{
if (first == null && second == null)
{
return true;
}
if (first == null || second == null)
{
return false;
}
Type firstType = first.GetType();
if (second.GetType() != firstType)
{
return false; // Or throw an exception
}
// This will only use public properties. Is that enough?
foreach (PropertyInfo propertyInfo in firstType.GetProperties())
{
if (propertyInfo.CanRead)
{
object firstValue = propertyInfo.GetValue(first, null);
object secondValue = propertyInfo.GetValue(second, null);
if (!object.Equals(firstValue, secondValue))
{
return false;
}
}
}
return true;
}
【讨论】：
我知道这可能有点矫枉过正，但这是我用于此目的的 ObjectComparer 类：
/// <summary>
/// Utility class for comparing objects.
/// </summary>
public static class ObjectComparer
{
/// <summary>
/// Compares the public properties of any 2 objects and determines if the properties of each
/// all contain the same value.
/// <para>
/// In cases where object1 and object2 are of different Types (both being derived from Type T)
/// we will cast both objects down to the base Type T to ensure the property comparison is only
/// completed on COMMON properties.
/// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
/// both objects will be cast to Foo for comparison)
/// </para>
/// </summary>
/// <typeparam name="T">Any class with public properties.</typeparam>
/// <param name="object1">Object to compare to object2.</param>
/// <param name="object2">Object to compare to object1.</param>
/// <param name="propertyInfoList">A List of <see cref="PropertyInfo"/> objects that contain data on the properties
/// from object1 that are not equal to the corresponding properties of object2.</param>
/// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
public static bool GetDifferentProperties<T> ( T object1 , T object2 , out List<PropertyInfo> propertyInfoList )
where T : class
{
return GetDifferentProperties<T>( object1 , object2 , null , out propertyInfoList );
}
/// <summary>
/// Compares the public properties of any 2 objects and determines if the properties of each
/// all contain the same value.
/// <para>
/// In cases where object1 and object2 are of different Types (both being derived from Type T)
/// we will cast both objects down to the base Type T to ensure the property comparison is only
/// completed on COMMON properties.
/// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
/// both objects will be cast to Foo for comparison)
/// </para>
/// </summary>
/// <typeparam name="T">Any class with public properties.</typeparam>
/// <param name="object1">Object to compare to object2.</param>
/// <param name="object2">Object to compare to object1.</param>
/// <param name="ignoredProperties">A list of <see cref="PropertyInfo"/> objects
/// to ignore when completing the comparison.</param>
/// <param name="propertyInfoList">A List of <see cref="PropertyInfo"/> objects that contain data on the properties
/// from object1 that are not equal to the corresponding properties of object2.</param>
/// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
public static bool GetDifferentProperties<T> ( T object1 , T object2 , List<PropertyInfo> ignoredProperties , out List<PropertyInfo> propertyInfoList )
where T : class
{
propertyInfoList = new List<PropertyInfo>();
// If either object is null, we can't compare anything
if ( object1 == null || object2 == null )
{
return false;
}
Type object1Type = object1.GetType();
Type object2Type = object2.GetType();
// In cases where object1 and object2 are of different Types (both being derived from Type T)
// we will cast both objects down to the base Type T to ensure the property comparison is only
// completed on COMMON properties.
// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
// both objects will be cast to Foo for comparison)
if ( object1Type != object2Type )
{
object1Type = typeof ( T );
object2Type = typeof ( T );
}
// Remove any properties to be ignored
List<PropertyInfo> comparisonProps =
RemoveProperties( object1Type.GetProperties() , ignoredProperties );
foreach ( PropertyInfo object1Prop in comparisonProps )
{
Type propertyType = null;
object object1PropValue = null;
object object2PropValue = null;
// Rule out an attempt to check against a property which requires
// an index, such as one accessed via this[]
if ( object1Prop.GetIndexParameters().GetLength( 0 ) == 0 )
{
// Get the value of each property
object1PropValue = object1Prop.GetValue( object1 , null );
object2PropValue = object2Type.GetProperty( object1Prop.Name ).GetValue( object2 , null );
// As we are comparing 2 objects of the same type we know
// that they both have the same properties, so grab the
// first non-null value
if ( object1PropValue != null )
propertyType = object1PropValue.GetType().GetInterface( "IComparable" );
if ( propertyType == null )
if ( object2PropValue != null )
propertyType = object2PropValue.GetType().GetInterface( "IComparable" );
}
// If both objects have null values or were indexed properties, don't continue
if ( propertyType != null )
{
// If one property value is null and the other is not null,
// they aren't equal; this is done here as a native CompareTo
// won't work with a null value as the target
if ( object1PropValue == null || object2PropValue == null )
{
propertyInfoList.Add( object1Prop );
}
else
{
// Use the native CompareTo method
MethodInfo nativeCompare = propertyType.GetMethod( "CompareTo" );
// Sanity Check:
// If we don't have a native CompareTo OR both values are null, we can't compare;
// hence, we can't confirm the values differ... just go to the next property
if ( nativeCompare != null )
{
// Return the native CompareTo result
bool equal = ( 0 == (int) ( nativeCompare.Invoke( object1PropValue , new object[] {object2PropValue} ) ) );
if ( !equal )
{
propertyInfoList.Add( object1Prop );
}
}
}
}
}
return propertyInfoList.Count == 0;
}
/// <summary>
/// Compares the public properties of any 2 objects and determines if the properties of each
/// all contain the same value.
/// <para>
/// In cases where object1 and object2 are of different Types (both being derived from Type T)
/// we will cast both objects down to the base Type T to ensure the property comparison is only
/// completed on COMMON properties.
/// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
/// both objects will be cast to Foo for comparison)
/// </para>
/// </summary>
/// <typeparam name="T">Any class with public properties.</typeparam>
/// <param name="object1">Object to compare to object2.</param>
/// <param name="object2">Object to compare to object1.</param>
/// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
public static bool HasSamePropertyValues<T> ( T object1 , T object2 )
where T : class
{
return HasSamePropertyValues<T>( object1 , object2 , null );
}
/// <summary>
/// Compares the public properties of any 2 objects and determines if the properties of each
/// all contain the same value.
/// <para>
/// In cases where object1 and object2 are of different Types (both being derived from Type T)
/// we will cast both objects down to the base Type T to ensure the property comparison is only
/// completed on COMMON properties.
/// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
/// both objects will be cast to Foo for comparison)
/// </para>
/// </summary>
/// <typeparam name="T">Any class with public properties.</typeparam>
/// <param name="object1">Object to compare to object2.</param>
/// <param name="object2">Object to compare to object1.</param>
/// <param name="ignoredProperties">A list of <see cref="PropertyInfo"/> objects
/// to ignore when completing the comparison.</param>
/// <returns>A boolean value indicating whether or not the properties of each object match.</returns>
public static bool HasSamePropertyValues<T> ( T object1 , T object2 , List<PropertyInfo> ignoredProperties )
where T : class
{
// If either object is null, we can't compare anything
if ( object1 == null || object2 == null )
{
return false;
}
Type object1Type = object1.GetType();
Type object2Type = object2.GetType();
// In cases where object1 and object2 are of different Types (both being derived from Type T)
// we will cast both objects down to the base Type T to ensure the property comparison is only
// completed on COMMON properties.
// (ex. Type T is Foo, object1 is GoodFoo and object2 is BadFoo -- both being inherited from Foo --
// both objects will be cast to Foo for comparison)
if ( object1Type != object2Type )
{
object1Type = typeof ( T );
object2Type = typeof ( T );
}
// Remove any properties to be ignored
List<PropertyInfo> comparisonProps =
RemoveProperties( object1Type.GetProperties() , ignoredProperties );
foreach ( PropertyInfo object1Prop in comparisonProps )
{
Type propertyType = null;
object object1PropValue = null;
object object2PropValue = null;
// Rule out an attempt to check against a property which requires
// an index, such as one accessed via this[]
if ( object1Prop.GetIndexParameters().GetLength( 0 ) == 0 )
{
// Get the value of each property
object1PropValue = object1Prop.GetValue( object1 , null );
object2PropValue = object2Type.GetProperty( object1Prop.Name ).GetValue( object2 , null );
// As we are comparing 2 objects of the same type we know
// that they both have the same properties, so grab the
// first non-null value
if ( object1PropValue != null )
propertyType = object1PropValue.GetType().GetInterface( "IComparable" );
if ( propertyType == null )
if ( object2PropValue != null )
propertyType = object2PropValue.GetType().GetInterface( "IComparable" );
}
// If both objects have null values or were indexed properties, don't continue
if ( propertyType != null )
{
// If one property value is null and the other is not null,
// they aren't equal; this is done here as a native CompareTo
// won't work with a null value as the target
if ( object1PropValue == null || object2PropValue == null )
{
return false;
}
// Use the native CompareTo method
MethodInfo nativeCompare = propertyType.GetMethod( "CompareTo" );
// Sanity Check:
// If we don't have a native CompareTo OR both values are null, we can't compare;
// hence, we can't confirm the values differ... just go to the next property
if ( nativeCompare != null )
{
// Return the native CompareTo result
bool equal = ( 0 == (int) ( nativeCompare.Invoke( object1PropValue , new object[] {object2PropValue} ) ) );
if ( !equal )
{
return false;
}
}
}
}
return true;
}
/// <summary>
/// Removes any <see cref="PropertyInfo"/> object in the supplied List of
/// properties from the supplied Array of properties.
/// </summary>
/// <param name="allProperties">Array containing master list of
/// <see cref="PropertyInfo"/> objects.</param>
/// <param name="propertiesToRemove">List of <see cref="PropertyInfo"/> objects to
/// remove from the supplied array of properties.</param>
/// <returns>A List of <see cref="PropertyInfo"/> objects.</returns>
private static List<PropertyInfo> RemoveProperties (
IEnumerable<PropertyInfo> allProperties , IEnumerable<PropertyInfo> propertiesToRemove )
{
List<PropertyInfo> innerPropertyList = new List<PropertyInfo>();
// Add all properties to a list for easy manipulation
foreach ( PropertyInfo prop in allProperties )
{
innerPropertyList.Add( prop );
}
// Sanity check
if ( propertiesToRemove != null )
{
// Iterate through the properties to ignore and remove them from the list of
// all properties, if they exist
foreach ( PropertyInfo ignoredProp in propertiesToRemove )
{
if ( innerPropertyList.Contains( ignoredProp ) )
{
innerPropertyList.Remove( ignoredProp );
}
}
}
return innerPropertyList;
}
}
【讨论】：
Type.GetProperties 将列出给定类型的每个属性。然后使用PropertyInfo.GetValue 检查值。
【讨论】：
是的。使用Reflection。使用反射，您可以执行以下操作：
//given object of some type
object myObjectFromSomewhere;
Type myObjOriginalType = myObjectFromSomewhere.GetType();
PropertyInfo[] myProps = myObjOriginalType.GetProperties();
然后您可以使用生成的 PropertyInfo 类来比较各种事物。
【讨论】：