Nested objects to one object using Automapper

Question

Have a requirement to map name (Class A) and phone number (Class B) to Class C which has both Name and PhoneNumber. A person (name) can have more than one phone numbers.

public class A
{
    public int ID { get; set; }
    public string Name { get; set; }
    public virtual IList<B> B { get; set; }
}

public class B
{
    public int A_ID { get; set; }
    public string PhoneNumber { get; set; }
}

public class C
{
    public string Name { get; set; }
    public string PhoneNumber { get; set; }
}

Getting A class (which has B) details from the database and it needs to be mapped to Class C.

public class Activity
{
    public IList<C> GetContacts(string name)
    {
        using (ModelEntities ctx = new ModelEntities())
        {
            Mapper.CreateMap<A, C>();
            Mapper.CreateMap<B, C>();

            var result =
                ctx.A.SingleOrDefault(ss => ss.Name == name);

        }
    }
}

Can anyone help me to map using Automapper?

Thanks

A person (name) can have more than one phone numbers... Aside from not showing any attempt, you haven't described what should happen in this scenario. Class C expects one number per one name. — Jonesopolis
– Jonesopolis, Commented Dec 11, 2015 at 16:25
Class C should provide all the records from the db. If we have records 1. Sam | 0786878768, 2. Sam|065765768, 3. Isaac | 8976897987, 4. Philip | 232342, GetContacts should fetch all 4 records. — techy
– techy, Commented Dec 11, 2015 at 16:28
That makes no sense. Class C can't provide all the records, IEnumerable<C> perhaps could, but you can't have a single instance represent multiple instances. — Chris Pratt
– Chris Pratt, Commented Dec 11, 2015 at 16:32
Yes I meant IList<C>, GetContacts return type is IList<C>. Will update my comment as well. — techy
– techy, Commented Dec 11, 2015 at 16:36

Chris Pratt · Accepted Answer · 2015-12-11 16:39:30Z

1

AutoMapper cannot map from a single instances to multiple instances. It either must be instance to instance or enumerable to enumerable. The best path forward I can see is to simply map your IList<B> to IList<C> and then back-fill the Name property. Something along the lines of:

var c = Mapper.Map<IList<C>>(a.B);
c.ToList().ForEach(m => m.Name = a.Name);

However, unless your mapping is hella more complex than this, AutoMapper is overkill. You could simply do:

var c = a.B.Select(b => new C { Name = a.Name, PhoneNumber = b.PhoneNumber });

answered Dec 11, 2015 at 16:39

Chris Pratt

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1 Comment

techy Over a year ago

Thanks. I'll try this.

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