Auto Mapper convert from string to Int

Question

I am creating a simple MVC4 application

I have a automapper

 Mapper.CreateMap<SourceClass, DestinationClass>()
      .ForMember(dest => dest.IntphoneNo, 
                  opt => opt.MapFrom(src => src.Stringphoneno));

IntphoneNo is of DataType int ( IntphoneNo is an variable of my class Person) Source attribute Stringphoneno is of Datatype string.

When i am mapping , i am getting follwoing error.

An exception of type 'AutoMapper.AutoMapperMappingException' occurred in AutoMapper.dll but was not handled in user code

But when i am changing the Dataype of IntphoneNo from int to string then my program is running successfully.

Unfortunately i cant change the Datatype inmy model

Is theer any way to change Datatupe in mapping .. Something like below

.ForMember(dest => dest.IntphoneNo, 
                  opt => opt.MapFrom(src => src.Int32(Stringphoneno));

After some research I came one step futher ..
If my StringPhoneNo is = 123456
then follwoing code is working. I dont need to parse it to string

Mapper.CreateMap<SourceClass, DestinationClass>()
      .ForMember(dest => dest.IntphoneNo, 
                  opt => opt.MapFrom(src => src.Stringphoneno));

but when my StringPhoneNo is = 12 3456 ( there is a space after 12) then my code is not working. Is there any way to trim spaces in Stringphoneno (Stringphoneno i am geting from webservice) in automapper.

Something like below..

Mapper.CreateMap<SourceClass, DestinationClass>()
      .ForMember(dest => dest.IntphoneNo, 
                  opt => opt.MapFrom(src => src.Trim(Stringphoneno))); 

Answer 1

Mapper.CreateMap<SourceClass, DestinationClass>() 
    .ForMember(dest => dest.IntphoneNo, 
        opt => opt.MapFrom(src => int.Parse(src.Stringphoneno)));

Here is some sample working code using the map described

class SourceClass
{
    public string Stringphoneno { get; set; }
}

class DestinationClass
{
    public int IntphoneNo { get; set; }
}

var source = new SourceClass {Stringphoneno = "8675309"};
var destination = Mapper.Map<SourceClass, DestinationClass>(source);

Console.WriteLine(destination.IntphoneNo); //8675309

Answer 2

The problem you may face is when it is unable to parse the string, one option would be to use a ResolveUsing:

Mapper.CreateMap<SourceClass, DestinationClass>() 
.ForMember(dest => dest.intphoneno, opts => opts.ResolveUsing(src =>
                double.TryParse(src.strphoneno, out var phoneNo) ? phoneNo : default(double)));

Answer 3

Yuriy Faktorovich's solution can be generalized for all strings that should be converted to ints by defining an extension method for IMappingExpression and usage of some custom attribute:

[AttributeUsage(AttributeTargets.Property)]
public class StringToIntConvertAttribute : Attribute
{
}

// tries to convert string property value to integer
private static int GetIntFromString<TSource>(TSource src, string propertyName)
{
    var propInfo = typeof(TSource).GetProperty(propertyName);
    var reference = (propInfo.GetValue(src) as string);
    if (reference == null)
        throw new MappingException($"Failed to map type {typeof(TSource).Name} because {propertyName} is not a string);

    // TryParse would be better
    var intVal = int.Parse(reference);
    return intVal;
}

public static IMappingExpression<TSource, TDestination> StringToIntMapping<TSource, TDestination>(this IMappingExpression<TSource, TDestination> expression)
{
    var srcType = typeof(TSource);
    foreach (var property in srcType.GetProperties().Where(p => p.GetCustomAttributes(typeof(StringToIntConvertAttribute), inherit: false).Length > 0))
    {
        expression.ForMember(property.Name, opt => opt.MapFrom(src => GetIntFromString(src, property.Name)));
    }

    return expression;
}

In order to make this work, the following steps must be performed:

1. Mapping between source and destination must append the mapping extension. E.g.:

   var config = new MapperConfiguration(cfg =>
   {
      // other mappings
   
      cfg.CreateMap<SrcType, DestType>().StringToIntMapping();
   });
   

2. Apply the attribute to all source string properties that must automatically be converted to integer values

Answer 4

Here's a simpler, but less scalable approach. Whenever you call Mapper.Initialize, remember to call .ToInt() or you'll get a run time error.

public class NumberTest
{
    public static void Main(string[] args)
    {
        Console.WriteLine("".ToInt());
        // 0
        Console.WriteLine("99".ToInt());
        // 99
    }
}

public static class StringExtensions
{
    public static int ToInt(this string text)
    {
        int num = 0;
        int.TryParse(text, out num);
        return num;
    }
}

// Use like so with Automapper
.ForMember(dest => dest.WidgetID, opts => opts.MapFrom(src => src.WidgetID.ToInt()));