CODEWITHSUNDEEP
c#.netautomapper
Gan3i
Gan3i

Reputation: 107

how to map only if destination object doesn't have a value in Automapper

I have a mapper in place and I need to perform a conditional mapping, Condition is, map the value from source to destination only if the destination property value is null. How would I do that? 

.ForMember(o => o.EmployeeId, opt => opt.MapFrom(u => u.EmployeeId))

I want to assign value to EmployeeId only if it does't have a value already.

Upvotes: 2

Views: 2355

Answers (2)

Allen Rufolo
Allen Rufolo

Reputation: 1202

Late answer but may help someone. This is what ended up working for me in ASP Net 6

//Only add email address if email is null or empty on the destination user object
CreateMap<UserProfile, User>()
            .ForMember(dest => dest.Email, opt => opt.PreCondition((src, dest, ctx) => string.IsNullOrEmpty(dest.Email)));

Upvotes: 0

Caleb Krise
Caleb Krise

Reputation: 21

The method of IMemberConfigurationExpression .MapFrom() has the overload that takes an IDestination void MapFrom<TResult>(Func<TSource, TDestination, TResult> mappingFunction); In your mapping function you can check the destination object.

Example:

.ForMember(dest => dest.EmployeeId, opt => opt.MapFrom((src, dest) => dest ?? src.EmployeeId))

Upvotes: 2

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