CODEWITHSUNDEEP
entity-frameworkentity-framework-coremany-to-manyautomapper
Oleg Sh
Oleg Sh

Reputation: 9013

Automapper: map many-to-many

I have the following model:

public class Device
{
    public string DeviceId { get; set; }
    public string DeviceName { get; set; }

    private ICollection<TagDevice> _tagDevices;
    public virtual ICollection<TagDevice> TagDevices { get => _tagDevices ?? (_tagDevices = new List<TagDevice>()); protected set => _tagDevices = value; }

}

public class Tag : BaseEntity
{
    public string Name { get; set; }

    private ICollection<TagDevice> _tagDevices;
    public virtual ICollection<TagDevice> TagDevices { get => _tagDevices ?? (_tagDevices = new List<TagDevice>()); protected set => _tagDevices = value; }
}


public class TagDevice
{
    public int TagId { get; set; }
    public string DeviceId { get; set; }

    public virtual Tag Tag { get; set; }
    public virtual Device Device { get; set; }
}

I have DTO class:

public class TagDisplayDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime CreatedAt { get; set; }
    public DateTime? UpdatedAt { get; set; }
    public int TimesUsed { get; set; }
    public int CarrierId { get; set; }
}

public class DeviceDisplayDto
{
    public string DeviceId { get; set; }
    public string DeviceName { get; set; }

    public List<TagDisplayDto> Tags { get; set; }    
}

now, I want to create mapping for DeviceDisplayDto with Tags filled:

        CreateMap<Device, DeviceDisplayDto>()
            .ForMember(d => d.Tags, opt => opt.MapFrom(s => s.TagDevices...))
            ;

TagDevices is collection and not a Tag type, each element of collection has property with Tag type. How to create it?

Upvotes: 0

Views: 137

Answers (1)

Prolog
Prolog

Reputation: 3354

You can use Select() on collection of TagDevices to transform it into list of TagDisplayDtos:

CreateMap<Device, DeviceDisplayDto>()
    .ForMember(deviceDisplayDto => deviceDisplayDto.Tags, options =>
        options.MapFrom(device => device.TagDevices.Select(tagDevice => new TagDisplayDto
        {
            CarrierId = 123,                // TODO
            CreatedAt = DateTime.UtcNow,    // TODO
            Id = tagDevice.TagId,
            Name = tagDevice.Tag.Name,
            TimesUsed = 0,                  // TODO
            UpdatedAt = DateTime.UtcNow,    // TODO
        }).ToList()));

I marked some properties as TODO since I don't know the whole model you are using and some properties are missing. You'll need to fill it out on your own. At least that code should get you started.

Edit #1

As Lucian suggested, even better solution is to fully use AutoMapper functionality. Create mappings between two models:

  • from Device to DeviceDisplayDto
  • from TagDevice to TagDisplayDto
CreateMap<Device, DeviceDisplayDto>()
    .ForMember(deviceDisplayDto => deviceDisplayDto.Tags, options =>
        options.MapFrom(device => device.TagDevices));
CreateMap<TagDevice, TagDisplayDto>()
    .ForMember(tagDisplayDto => tagDisplayDto.CarrierId, options =>
        options.MapFrom(tagDevice => 123))                          // TODO
    .ForMember(tagDisplayDto => tagDisplayDto.CreatedAt, options =>
        options.MapFrom(tagDevice => DateTime.UtcNow.AddDays(-60))) // TODO
    .ForMember(tagDisplayDto => tagDisplayDto.Id, options =>
        options.MapFrom(tagDevice => tagDevice.TagId))
    .ForMember(tagDisplayDto => tagDisplayDto.Name, options =>
        options.MapFrom(tagDevice => tagDevice.Tag.Name))
    .ForMember(tagDisplayDto => tagDisplayDto.TimesUsed, options =>
        options.MapFrom(tagDevice => 0))                            // TODO
    .ForMember(tagDisplayDto => tagDisplayDto.UpdatedAt, options =>
        options.MapFrom(tagDevice => DateTime.UtcNow));             // TODO

That way, mapping logic defined above is reusable. Similarly to my first solution, you'd have to fill out properties marked with TODO on your own.

Upvotes: 1

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