在C#中动态更改数据类型 [英] Change data type dynamically in c#

问题描述

我想动态转换数据类型.

I want to convert the data type dynamically.

我的代码:

private static void updateValues(SqlDataReader reader)  
{
        USR_AddressItem item = new USR_AddressItem();
        Type ConvertNewType;
        ConvertNewType = Type.GetType(item.UserId.GetType().Name);
        item.UserId = (ConvertNewType)(reader[UserDAL.USR_Address.FieldNames.UserId]);

}

仅动态输入数据类型.因为我想在运行时为该变量赋值.我将从 SqlDataReader 中获取值.该读取器始终返回字符串值.我将在全球范围内使用此方法.

Here data type only in dynamically. Because I want to assign value this variable in run time. I will get values from SqlDataReader. This reader return always string values. I am going to use this method globally.

推荐答案

好吧，您所需要的称为类型推断

Well, what you need is called type inference

您不需要事先知道数据类型，就可以让运行时动态地解决它，如下所示:

You don't need to know the data type in advance, you let the runtime solve it on the fly, like this:

private static void updateValues(SqlDataReader reader)  
{
    USR_AddressItem item = new USR_AddressItem();
    item.UserId = GetConverter(item.UserId)(reader[UserDAL.USR_Address.FieldNames.UserId]);
}

我的魔力在这里:

static Func<string, T>  GetConverter<T>(T example)      
{
    return (x) => Convert<T>(x); 
}


static T Convert<T>(string val)
{
        Type destiny = typeof(T);

        // See if we can cast           
        try
        {
            return (T)(object)val;
        }
        catch { }

        // See if we can parse
        try
        {
            return (T)destiny.InvokeMember("Parse", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.InvokeMethod | System.Reflection.BindingFlags.Public, null, null, new object[] { val });
        }
        catch { }

        // See if we can convert
        try
        {
            Type convertType = typeof(Convert);
            return (T)convertType.InvokeMember("To" + destiny.Name, System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.InvokeMethod | System.Reflection.BindingFlags.Public, null, null, new object[] { val });
        }
        catch { }

        // Give up
        return default(T);
    }

这篇关于在C#中动态更改数据类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！