Get first object in child collection inside projection - linq

Question

I have the following entities:
public class Mark {
public Int32 Id { get; set; }
public DateTime Created { get; set; }
public virtual ICollection<MarkLocalized> MarksLocalized { get; set; }
} // Mark
public class MarkLocalized {
public Int32 Id { get; set; }
public String Culture { get; set; }
public String Name { get; set; }
public virtual Mark Mark { get; set; }
} // MarkLocalized
Given a culture, for example "en", I need to get all Marks, their localized name for the given culture and map them to a MarkModel:
public class MarkModel {
public Int32 Id { get; set; }
public String Name { get; set; }
} // MarkModel
I tried the following:
Context context = new Context();
context.Marks
.SelectMany(x => x.MarksLocalized, (y, z) =>
new MarkModel {
Id = y.Id,
Name = z.Name,
Slug = z.Slug
});
But I need only the MarksLocalized which culture is equal to the given culture.
How can I do this?
Thank you,
Miguel

Answer 1

You can add Where inside SelectMany:
Context context = new Context();
context.Marks
.SelectMany(x => x.MarksLocalized.Where(x => x.Culture == "en"), (y, z) =>
new MarkModel {
Id = y.Id,
Name = z.Name,
Slug = z.Slug
});
But should be more clear with syntax query:
from m in new Context.Marks
from l in m.MarksLocalized
where l.Culture == "en"
select new MarkModel { m.ID, m.Name, l.Slug }
which should be translated into following query by compiler:
context.Marks
.SelectMany(x => x.MarksLocalized, (m, l) => new { m, l })
.Where(x => x.l.Culture == "en")
.Select(x => new MarkModel { x.m.ID, x.m.Name, x.l.Slug })
which should produce exact same results as first one.