Get data by ForeignKey

Question

I have MainClass and a ChildData.

I need to get ChildData given a MainClass.

The MainClass has a Property called ChildClassProperty. ChildData has got a ForeignKey to MainClass. How do I get the ChildData using LINQ?

so far:

using (var ctx = Csla.Data.ObjectContextManager<DB.Data.Entities>.GetManager(Model.EntitiesDatabase.Name))
{
    var xxx = from a in ctx.ObjectContext.ChildData where a...
}

Answer 1

ChildData has a foreign key to MainClass. Do something like:

Entities:

public ChildData
{
    public int Id { get; set; } // primary key
    public int MainClassId { get; set; } // foreign key
    public string Data { get; set; }
}

public MainClass
{
    public int Id { get; set; } // primary key
    public string Data { get; set; }
}

Queries:

public IQueryable<ChildData> GetChildData(int mainClassId)

using (var ctx = Csla.Data.ObjectContextManager<DB.Data.Entities>.GetManager(Model.EntitiesDatabase.Name))
{
    return ctx.ObjectContext.ChildData.Where(x => x.MainClassId == mainClassId);
}

or by passing in a full MainClass instance:

public IQueryable<ChildData> GetChildData(MainClass mainClass)

using (var ctx = Csla.Data.ObjectContextManager<DB.Data.Entities>.GetManager(Model.EntitiesDatabase.Name))
{
    return ctx.ObjectContext.ChildData.Where(x => x.MainClassId == mainClass.Id);
}