Fill data in ObservableCollection using LINQ - wpf

Question

I have a structure as below.
public class CategoryClass
{
public decimal Category_ID { get; set; }
public string Category_Name { get; set; }
//public System.Nullable<char> _Category_Type;
public ObservableCollection<DAL.SubCategoryClass> SubCat { get; set; }
}
public class SubCategoryClass
{
public decimal Sub_Category_ID { get; set; }
public string Sub_Category_Name { get; set; }
public decimal Category_ID { get; set; }
}
I need to fill data using LINQ.
I have some code here, please correct me to solve it.
public ObservableCollection<DAL.CategoryClass> GetCategoryandSubCategory()
{
var cat = from c in dbc.Categories
select new DAL.CategoryClass
{
Category_ID = c.Category_ID,
Category_Name = c.Category_Name,
SubCat = from d in dbc.Sub_Categories
where d.Category_ID == c.Category_ID
select new DAL.SubCategoryClass
{
Sub_Category_ID = d.Sub_Category_ID,
Sub_Category_Name = d.Sub_Category_Name,
Category_ID = d.Category_ID
}
};
}
Also suggest me some examples of validation tech in WPF.

Answer 1

One option is to just return an IEnumerable.
That may serve your needs.
If you need an ObservableCollection then you need to new it.
For List just .ToList()
As for validation one question at time.
Start with searching MSDB for validation.
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
System.Diagnostics.Debug.WriteLine(OCint.Count.ToString());
}
List<SimpleClass> baseList = new List<SimpleClass> { new SimpleClass(1), new SimpleClass(2), new SimpleClass(3) };
public IEnumerable<SimpleClass> iEint
{
get { return baseList.Where(x => x.ID < 3).Select(w=> new SimpleClass(w.ID)); }
}
public List<SimpleClass> Lint
{
get { return iEint.ToList(); ; }
}
public ObservableCollection<SimpleClass> OCint
{
get { return new ObservableCollection<SimpleClass>(iEint); }
}
}
public class SimpleClass
{
public Int32 ID { get; private set; }
public SimpleClass ( Int32 id) { ID = id; }
}

Answer 2

public IEnumerable<DAL.CategoryClass> GetCategoryandSubCategory()
{
ObservableCollection<DAL.SubCategoryClass> s = new ObservableCollection<DAL.SubCategoryClass>();
var cat = from c in dbc.Categories
select new DAL.CategoryClass
{
Category_ID = c.Category_ID,
Category_Name = c.Category_Name,
SubCat =s.Add( from d in dbc.Sub_Categories
where d.Category_ID == c.Category_ID
select new DAL.SubCategoryClass
{
Sub_Category_ID = d.Sub_Category_ID,
Sub_Category_Name = d.Sub_Category_Name,
Category_ID = d.Category_ID
}
};).ToList()
return cat ;
}
hope it work with u

Answer 3

If you want GetCategoryandSubCategory() returns ObservableCollection that is refreshed automatically when dbc.Categories changes or CategoryClass (SubCotegory) properties change, you can use my ObservableComputations library. Using that library you can code:
public ObservableCollection<DAL.CategoryClass> GetCategoryandSubCategory()
{
var cat = dbc.Categories.Selecting(c =>
new DAL.CategoryClass
{
Category_ID = c.Category_ID,
Category_Name = c.Category_Name,
SubCat = dbc.Sub_Categories
.Filtering(d => d.Category_ID == c.Category_ID)
.Selecting(d => new DAL.SubCategoryClass
{
Sub_Category_ID = d.Sub_Category_ID,
Sub_Category_Name = d.Sub_Category_Name,
Category_ID = d.Category_ID
})
});
}
To make code above working dbc.Categories and dbc.Sub_Categories must be of type ObservableCollection and all the classes mentioned in the code must implement INotifyPropertyChanged.