[英]how to map only if destination object doesn't have a value in Automapper
我有一个映射器,我需要执行条件映射,条件是,map 仅当目标属性值为 null 时,才从源到目标的值。我该怎么做?
.ForMember(o => o.EmployeeId, opt => opt.MapFrom(u => u.EmployeeId))
仅当 EmployeeId 还没有值时,我才想为它赋值。
IMemberConfigurationExpression
.MapFrom()
具有重载,该重载采用 IDestination void MapFrom<TResult>(Func<TSource, TDestination, TResult> mappingFunction);
在您的映射函数中,您可以检查目标对象。
例子:
.ForMember(dest => dest.EmployeeId, opt => opt.MapFrom((src, dest) => dest.EmployeeId ?? src.EmployeeId))
应该能帮到你
CreateMap<YOURMODEL,YOURMODEL2>()
.ForMember(dest => dest.EmployeeId, opt => {
opt.PreCondition(src => src.EmployeeId != null);
opt.MapFrom(src => src.EmployeeId);
另一种方式
CreateMap<SourceClass, TargetClass>()
.ForMember(d => d.EmployeeId, o => o.MapFrom(s => s.EmployeeId))
.ForAllMembers(o => o.Condition((src, dest, value) => value != null));
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