AutoMapper: Why is UseValue only executed once

问题

Why is UseValue only executed once? I need to call the TeamRepository for each request.

How can I achieve this?

Mapping from TeamEmployee to TeamEmployeeInput:

CreateMap<TeamEmployee, TeamEmployeeInput>()
    .ForMember(x => x.Teams, x => x.UseValue(GetTeamEmployeeInputs()))
    .ForMember(d => d.SelectedTeam, s => s.MapFrom(x => x.Team == null ? 0 : x.Team.Id));

private IEnumerable<TeamDropDownInput> GetTeamEmployeeInputs()
{
    Team[] teams = CreateDependency<ITeamRepository>().GetAll();
    return Mapper.Map<Team[], TeamDropDownInput[]>(teams);
}

Domain object:

public class TeamEmployee : Entity
{
    public virtual Employee Employee { get; set; }
    public virtual Team Team { get; set; }
}

View model objects:

public class TeamEmployeeInput
{
    public int? Id { get; set; }
    public string EmployeeLastName { get; set; }
    public string EmployeeEMail { get; set; }
    public string EmployeeFirstName { get; set; }

    public int SelectedTeam { get; set; }

    public IList<TeamDropDownInput> Teams { get; set; }
}


public class TeamDropDownInput : IDropdownList
{
    public int Id { get; set; }
    public string Text { get; set; }
}

回答1:

Try the MapFrom option. It provides a delegate that will be called each time a map happens. From a quick DateTime test and my command window this seems to work.

Something like:

public class Foo {
    public DateTime bar { get; set; }
}

public class Foo1
{
    public DateTime bar1 { get; set; }
}
Mapper.CreateMap<Foo, Foo1>()
    .ForMember(x => x.bar1, opt => opt.MapFrom(x => DateTime.Now)); // not using x, your function returns the value for bar1

I have to point out that this is not the way AutoMapper is designed to work. AutoMapper should map properties from one model to another. So if the data does not exist on modelA you should not map that data to modelB.

Your code change would be:

CreateMap<TeamEmployee, TeamEmployeeInput>()
    .ForMember(x => x.Teams, x => x.MapFrom(x => GetTeamEmployeeInputs()))

来源：https://stackoverflow.com/questions/4662863/automapper-why-is-usevalue-only-executed-once

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mapping

viewmodel

automapper