Question

我正在尝试编写一个通用方法来比较两个对象（我故意有两种不同的类型进入。第二种具有与第一种相同的属性。第一种只有更多。）。

我想确保属性具有相同的值。以下代码适用于我在对象中的大多数属性，但偶尔会抛出：

“对象与目标类型不匹配”

...错误

var valFirst = prop.GetValue(manuallyCreated, null) as IComparable;

public static bool SameCompare<T, T2>(T manuallyCreated, T2 generated){
var propertiesForGenerated = generated.GetType().GetProperties();
int compareValue = 0;

foreach (var prop in propertiesForGenerated) {

    var valFirst = prop.GetValue(manuallyCreated, null) as IComparable;
    var valSecond = prop.GetValue(generated, null) as IComparable;
    if (valFirst == null && valSecond == null)
        continue;
    else if (valFirst == null) {
        System.Diagnostics.Debug.WriteLine(prop + "s are not equal");
        return false;
    }
    else if (valSecond == null) {
        System.Diagnostics.Debug.WriteLine(prop + "s are not equal");
        return false;
    }
    else if (prop.PropertyType == typeof(System.DateTime)) {
        TimeSpan timeDiff = (DateTime)valFirst - (DateTime)valSecond;
        if (timeDiff.Seconds != 0) {
            System.Diagnostics.Debug.WriteLine(prop + "s are not equal");
            return false;
        }
    }
    else
        compareValue = valFirst.CompareTo(valSecond);
    if (compareValue != 0) {
        System.Diagnostics.Debug.WriteLine(prop + "s are not equal");
        return false;
    }
}

System.Diagnostics.Debug.WriteLine("All values are equal");
return true;
}

Answer 1

在.NET中的类型上定义的每个属性都是不同的，即使它们具有相同的名称。你必须这样做：

foreach (var prop in propertiesForGenerated) 
{
    var otherProp = typeof(T).GetProperty(prop.Name);
    var valFirst = otherProp.GetValue(manuallyCreated, null) as IComparable;
    var valSecond = prop.GetValue(generated, null) as IComparable;

    ...

当然，这并未考虑T上定义的某些属性在T2上可能不存在，反之亦然。

Answer 2

因为manuallyCreated不属于T2类型。尝试在该类型上获取具有相同名称的属性对象，它应该可以工作（或者如果您假设T2中的所有属性也在T1中，您将获得更好的错误）：

public static bool SameCompare<T, T2>(T manuallyCreated, T2 generated){
    var propertiesForGenerated = typeof(T2).GetProperties();
    int compareValue = 0;

    foreach (var prop in propertiesForGenerated) {
        var firstProperty = typeof(T).GetProperty(prop.Name);
        var valFirst = firstProperty.GetValue(manuallyCreated, null) as IComparable;
        var valSecond = prop.GetValue(generated, null) as IComparable;
        ...
    }
}

Answer 3

我相信最好让您需要比较的属性的接口，然后我会继承IEqualityComparer<YourInterface>

以及Equals和GetHashCode

public bool Equals(YourInterface one, YourInterface two)
{
    return this.GetHashCode(one) == this.GetHashCode(two);
}

public int GetHashCode(YourInterface  test)
{
    if(test == null)
    {

      return 0;
    }

     int hash = 0;
     //// get hash or set int on each property.

     return hash;
 }

C＃ - GetValue - 对象与目标类型不匹配

3 个答案: