MapProperty on collections seem impossible

[JKetelaar]

So I'm a bit stuck and I'm staring at the documentation without answers at this point...

So say I have an entity class:

public class MyClass
{
    public ICollection<MyOtherClass> OtherItems { get; set; }
}

public class MyOtherClass
{
    public string Name { get; set; }
}

And a view class:

public class MyViewClass
{
    public IEnumerable<MyOtherViewClass> ViewItems { get; set; }
}

public class MyOtherViewClass
{
    public string SomeName { get; set; }
}

Now I want to map these to each other. Of course the mapping of OtherItems to ViewItems is fairly straight forward with MapProperty:

[MapProperty(nameof(MyClass.OtherItems), nameof(MyViewClass.ViewItems))]

But how do I map Name to SomeName?
I've already tried the following options:

1. Using MapProperty

[MapProperty("MyClass.OtherItems.Name", "MyViewClass.ViewItems.SomeName")]

Which does not seem to work;

Error RMG005

2. Using a custom method on the collection

    private static IEnumerable<MyOtherViewClass> ToView(this ICollection<MyClass> values)
    {
        return new List<MyOtherViewClass>();
    }

Which is then not used to map.

3. Using a custom method on the collection

    private static MyOtherViewClass ToView(this MyClass value)
    {
        return new MyOtherViewClass();
    }

Which is then also not used to map.

I'm out of ideas. Am I overseeing something or is this a bug?

[TimothyMakkison]

Hey, sorry to hear your stuck, 2/3 would be the recommended way of handling your issue. Unfortunately the function signatures are invalid.

1. Using MapProperty

[MapProperty("MyClass.OtherItems.Name", "MyViewClass.ViewItems.SomeName")]

This won't work for two reasons.

Firstly the member path is invalid as you have specified the type of the source and taget objects (MyClass & MyViewClass) therefore mapperly will look for members of the name MyClass inside MyClass.

Secondly OtherItems and ViewItems are enumerable so its not possible to map Name and SomeName, what you've done in 2. and 3. is the correct way to handle enumerables.

2. Using a custom method on the collection

It looks like you've made a mistake in your example you should use IEnumerable<MyOtherViewClass> ToView(this ICollection<MyOtherClass> values) which generates:

public static partial global::Riok.Mapperly.Sample.MyViewClass MapTo(global::Riok.Mapperly.Sample.MyClass src)
{
    var target = new global::Riok.Mapperly.Sample.MyViewClass();
    target.ViewItems = ToView(src.OtherItems);
    return target;
}

3. Using a custom method on the collection

Same issue as above:

[MapProperty(nameof(MyOtherClass.Name), nameof(MyOtherViewClass.SomeName))]
private static partial MyOtherViewClass MapToOtherViewClass(MyOtherClass src);

public static partial global::Riok.Mapperly.Sample.MyViewClass MapTo(global::Riok.Mapperly.Sample.MyClass src)
{
    var target = new global::Riok.Mapperly.Sample.MyViewClass();
    target.ViewItems = MapToIEnumerable(src.OtherItems);
    return target;
}

private static partial global::Riok.Mapperly.Sample.MyOtherViewClass MapToOtherViewClass(global::Riok.Mapperly.Sample.MyOtherClass src)
{
    var target = new global::Riok.Mapperly.Sample.MyOtherViewClass();
    target.SomeName = src.Name;
    return target;
}

private static global::System.Collections.Generic.IEnumerable<global::Riok.Mapperly.Sample.MyOtherViewClass> MapToIEnumerable(global::System.Collections.Generic.ICollection<global::Riok.Mapperly.Sample.MyOtherClass> source)
{
    var target = new global::Riok.Mapperly.Sample.MyOtherViewClass[source.Count];
    var i = 0;
    foreach (var item in source)
    {
        target[i] = MapToOtherViewClass(item);
        i++;
    }
    return target;
}

[JKetelaar]

This is incredibly informative, thank you so much. I completely missed the fact you can define mappers which are partial, but implicitly called (private).