json - Get related array from another table by foreign key -

i'm using sql server 2012, mvc webapi, automapper , entity framework. in database have 2 tables one-to-many relation, example categories , products; category can have more products product can have 1 category. want json each category contains array of related products products.categoryid field.

this made after search in internet:

public class categoriesviewmodel {     public string categoryname { get; set; }     public ienumerable<productsviewmodel> products { get; set; } }  public class productsviewmodel {     public string name { get; set; } }  public static class viewmodelmapper {     public static tdestination map<tdestination>(object source)     {         return mapper.map<tdestination>(source);     }      public static void registermaps()     {         automapper.mapper.initialize(config =>         {             config.createmap<products, productsviewmodel>().reversemap();             config.createmap<categories, categoriesviewmodel>()                 .formember(dest => dest.products, opt => opt.mapfrom(src => src.products))                 .reversemap();         }     } }  // repository public ienumerable<categoriesviewmodel> getcategories() {     return viewmodelmapper.map<ienumerable<categoriesviewmodel>>(context.categories); }  //business logic public ienumerable<categoriesviewmodel> getcategories() {     return repository.getcategories(); }  [route("categories"), httpget] public ihttpactionresult getcategories() {     return ok(bl.getcategories()); } 

my result list of categories , empty or null products array , cannot find solution.

how can reach result? thank you

edit:

entity framework models

public partial class category {     [system.diagnostics.codeanalysis.suppressmessage("microsoft.usage", "ca2214:donotcalloverridablemethodsinconstructors")]     public category()     {         this.products = new hashset<product>();     }      public int categoryid { get; set; }     public string categoryname { get; set; }      [system.diagnostics.codeanalysis.suppressmessage("microsoft.usage", "ca2227:collectionpropertiesshouldbereadonly")]     public virtual icollection<product> products { get; set; } }  public partial class product {     public int productid { get; set; }     public int categoryid { get; set; }     public string productname { get; set; }      public virtual category category { get; set; } } 

category , product examples, ignore if view model property names not same.

i suspect have lazy loading off.

so 1 solution turn on, not suggest it, because execute many database queries.

a better option use eager loading:

return viewmodelmapper.map<ienumerable<categoriesviewmodel>>(     context.categories.include(c => c.products)); 

or

return viewmodelmapper.map<ienumerable<categoriesviewmodel>>(     context.categories.include("products")); 

but best option automapper use projectto method queryableextensions:

retirn context.categories.projectto<categoriesviewmodel>(); 

for reasons explained in link.