Question

我使用C＃作为编程语言执行自动化

我有一个Enum在表中保存列。我在每个列名称的“描述”中保存这些列的数据类型。

每个列都是可排序的，排序后我想验证特定列的排序是否正确。我在列中创建数据列表，以编程方式对其进行排序，然后在屏幕上对其进行排序，读取内容，然后使用List.SequenceEquals

我正在尝试创建一个“类型”列表（在“描述”中指定）。但看起来我无法创建运行时对象列表。

对此有任何解决方案吗？

CODE

    {
    public enum tranColumns
    {
        [Description("DateTime")]
        InvoiceDate,
        [Description("string")]
        Customer,
        [Description("string")]
        InvoiceID,
        [Description("string")]
        LiabilityTypeDescription,
        [Description("string")]
        TransactionStatusDescription,
        [Description("string")]
        TestTransaction,
        [Description("string")]
        TransactionDate,
        [Description("int")]
        TransactionID,
        [Description("string")]
        SourceSystem,
        [Description("string")]
        ShipToGeocode,
        [Description("DateTime")]
        CreationTime
    }

var type = MyExtensions.GetDataType(tranColumns.InvoiceDate); //Gets System.Type

List<type> list= new List<type>();
}

        public static string GetEnumDescription(System.Enum value)
    {
        FieldInfo fi = value.GetType().GetField(value.ToString());
        DescriptionAttribute[] attributes =
            (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);

        if (attributes != null && attributes.Length > 0)
            return attributes[0].Description;
        else
            return value.ToString();
    }

    public static Type GetDataType(System.Enum value)
    {
        switch(GetEnumDescription(value).ToLower())
        {
            case "datetime":
                return typeof(DateTime);
            case "string":
                return typeof(String);
            case "int":
                return typeof(Int32);
            default:
                Utilities.log("Unkwown datatype",LogType.ErrorEntry);
                return typeof(Object);
        }
    }

无法以这种方式创建“类型”列表！

Answer 1

Type listType = typeof(List<>).MakeGenericType(type);
IList list= (IList)Activator.CreateInstance(listType);

您需要将IList.Add与对象一起使用，因为无法使用强制转换为List。我重新读了你的代码，似乎你可以编辑它并以这种方式创建列表：

public static List<T> CreateMyList<T>(System.Enum value)
    {
        switch(GetEnumDescription(value).ToLower())
        {
            case "datetime":
                return new List<DateTime>();
            case "string":
                return new List<String>();
            case "int":
                return new List<Int32>();
            default:
                Utilities.log("Unkwown datatype",LogType.ErrorEntry);
                return new List<Object>();
        }
    }

Answer 2

Linq救援！

            var type = MyExtensions.GetDataType(column as Enum);

        DataTable dtAscen; //=logic to read table;
        List<object> listBeforeSort = (from x in dtAscen.AsEnumerable()
                            select (object)Convert.ChangeType(x.Field<string>(column.ToString()), type)).ToList();
        var temp = listBeforeSort.OrderBy(s => s);
        if(!listBeforeSort.SequenceEqual(temp))            
            Utilities.log("Issue with ascending sort on column " + column.ToString(), LogType.ErrorEntry);

Answer 3

您可能需要Activator.CreateInstance方法（类型） https://msdn.microsoft.com/en-us/library/wccyzw83%28v=vs.110%29.aspx

  string[] instances = instanceSpec.Split(';');
    Array instlist = Array.CreateInstance(typeof(object), instances.Length);
    object item;
    for (int i = 0; i < instances.Length; i++)
    {
        // create the object from the specification string
        Console.WriteLine("Creating instance of: {0}", instances[i]);
        item = Activator.CreateInstance(Type.GetType(instances[i]));
        instlist.SetValue(item, i);
    }
    Console.WriteLine("\nObjects and their default values:\n");
    foreach (object o in instlist)
    {
        Console.WriteLine("Type:     {0}\nValue:    {1}\nHashCode: {2}\n",
            o.GetType().FullName, o.ToString(), o.GetHashCode());
    }

在运行时定义的类型的列表

3 个答案: