automapper. How to make it ignore properties in Destination for which there is no match in Source?

Question

.NET

There are classes BLL.Story (fewer properties) and DAL.Story (more properties).
When converting from DAL.Story to BLL.Story everything works. If you perform the reverse operation, then an exception is thrown:
{"Missing type map configuration or unsupported mapping.
Mapping types: RuntimeType -> Type System.RuntimeType -> AgilityTracker.DAL.Type
Destination path: Story.Type.Type
Source value: AgilityTracker.BLL .DataModel.Story"}
I assume that the mapper does not know how to fill in the fields in the Destination, which are not in the Source.
How to set up a mapper so that in such cases these fields are filled with default values ​​that are defined for their types, respectively?

Answer 1

Decision:

using System.Linq;
using System.Reflection;
using AutoMapper;

namespace AgilityTracker.BLL.Extension
{
    public static class MappingExpressionExtension
    {
        /// <summary>
        /// Игнорирует свойства в Destination для которых нет соотвествия в Source
        /// </summary>
        public static IMappingExpression<TSource, TDest> IgnoreAllUnmapped<TSource, TDest>(this IMappingExpression<TSource, TDest> expression)
        {
            var destinationProperties = typeof(TDest).GetProperties().Select<PropertyInfo, string>(s => s.Name);
            var sourceProperties = typeof(TSource).GetProperties().Select<PropertyInfo, string>(s => s.Name);
            var difference = destinationProperties.Except(sourceProperties);
            difference.Each(item => expression.ForMember(item, o => o.Ignore()));
            return expression;
        }
    }
}

Usage:

using AgilityTracker.BLL.Extension;
...
Mapper.CreateMap<Story, DAL.Story>()
                .IgnoreAllUnmapped();

There is no standard method, as I understand it, in AutoMapper?