通过反射查找可空属性的类型

Question

我通过反射检查对象的属性，并继续处理每个属性的数据类型。这是我的(简化)来源:

private void ExamineObject(object o)
{
  Type type = default(Type);
  Type propertyType = default(Type);
  PropertyInfo[] propertyInfo = null;
  type = o.GetType();
  propertyInfo = type.GetProperties(BindingFlags.GetProperty |
                                    BindingFlags.Public |
                                    BindingFlags.NonPublic |
                                    BindingFlags.Instance);
  // Loop over all properties
  for (int propertyInfoIndex = 0; propertyInfoIndex <= propertyInfo.Length - 1; propertyInfoIndex++)
  {
    propertyType = propertyInfo[propertyInfoIndex].PropertyType;
  }
}

我的问题是，我最近需要处理可空属性，但我不知道如何获得可空属性的类型

Answer 1

可能的解决方案:

    propertyType = propertyInfo[propertyInfoIndex].PropertyType;
    if (propertyType.IsGenericType &&
        propertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
    {
      propertyType = propertyType.GetGenericArguments()[0];
    }

Answer 2

Nullable.GetUnderlyingType(fi.FieldType) 将为您完成工作检查下面的代码做您想做的事情

System.Reflection.FieldInfo[] fieldsInfos = typeof(NullWeAre).GetFields();
        foreach (System.Reflection.FieldInfo fi in fieldsInfos)
        {
            if (fi.FieldType.IsGenericType
                && fi.FieldType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
            {
                // We are dealing with a generic type that is nullable
                Console.WriteLine("Name: {0}, Type: {1}", fi.Name, Nullable.GetUnderlyingType(fi.FieldType));
            }
    }

Answer 3

foreach (var info in typeof(T).GetProperties())
{
  var type = info.PropertyType;
  var underlyingType = Nullable.GetUnderlyingType(type);
  var returnType = underlyingType ?? type;
}

Answer 4

正如Yves M.指出的那样，情况如下:

var properties = typeof(T).GetProperties();
  foreach (var prop in properties)
  {
     var propType = Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType;
     var dataType = propType.Name;
  }

Answer 5

我使用循环来遍历所有类属性以获得属性类型。我使用以下代码:

public Dictionary<string, string> GetClassFields(TEntity obj)
{
    Dictionary<string, string> dctClassFields = new Dictionary<string, string>();
    foreach (PropertyInfo property in obj.GetType().GetProperties())
    {
        if (property.PropertyType.IsGenericType && property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) && property.PropertyType.GetGenericArguments().Length > 0)
            dctClassFields.Add(property.Name, property.PropertyType.GetGenericArguments()[0].FullName);
        else
            dctClassFields.Add(property.Name, property.PropertyType.FullName);
    }
    return dctClassFields;
}

Answer 6

此法简便、快捷、安全

public static class PropertyInfoExtension {
    public static bool IsNullableProperty(this PropertyInfo propertyInfo)
        => propertyInfo.PropertyType.Name.IndexOf("Nullable`", StringComparison.Ordinal) > -1;
}