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AutoMapper中用户自定义转换
Custom Type Converters
Sometimes, you need to take complete control over the conversion of one type to another. This is typically when one type looks nothing like the other, a conversion function already exists, and you would like to go from a "looser" type to a stronger type, such as a source type of string to a destination type of Int32.For example, suppose we have a source type of:
public class Source{ public string Value1 { get; set; } public string Value2 { get; set; } public string Value3 { get; set; }}
But you would like to map it to:
public class Destination{ public int Value1 { get; set; } public DateTime Value2 { get; set; } public Type Value3 { get; set; }}
If we were to try and map these two types as-is, AutoMapper would throw an exception (at map time and configuration-checking time), as AutoMapper does not know about any mapping from string to int, DateTime or Type. To create maps for these types, we must supply a custom type converter, and we have three ways of doing so:
void ConvertUsing(Func<TSource, TDestination> mappingFunction);void ConvertUsing(ITypeConverter<TSource, TDestination> converter);void ConvertUsing<TTypeConverter>() where TTypeConverter : ITypeConverter<TSource, TDestination>;
public interface ITypeConverter<TSource, TDestination>{ TDestination Convert(TSource source);}
And supply AutoMapper with either an instance of a custom type converter, or simply the type, which AutoMapper will instantiate at run time. The mapping configuration for our above source/destination types then becomes:
[Test]public void Example(){ Mapper.CreateMap<string, int>().ConvertUsing(Convert.ToInt32); Mapper.CreateMap<string, DateTime>().ConvertUsing(new DateTimeTypeConverter()); Mapper.CreateMap<string, Type>().ConvertUsing<TypeTypeConverter>(); Mapper.CreateMap<Source, Destination>(); Mapper.AssertConfigurationIsValid(); var source = new Source { Value1 = "5", Value2 = "01/01/2000", Value3 = "AutoMapperSamples.GlobalTypeConverters.GlobalTypeConverters+Destination" }; Destination result = Mapper.Map<Source, Destination>(source); result.Value3.ShouldEqual(typeof (Destination));}public class DateTimeTypeConverter : ITypeConverter<string, DateTime>{ public DateTime Convert(string source) { return System.Convert.ToDateTime(source); }}public class TypeTypeConverter : ITypeConverter<string, Type>{ public Type Convert(string source) { Type type = Assembly.GetExecutingAssembly().GetType(source); return type; }}
AutoMapper中用户自定义转换
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