private static void InitialiseData(GroupJoinContext context, bool ensureOneParentHasNoChildren)
{
CheckAndAddParent(context, 1);
CheckAndAddParent(context, 2);
CheckAndAddParent(context, 3);
CheckAndAddOtherParent(context, 1);
CheckAndAddOtherParent(context, 2);
CheckAndAddChild(context, 1, 1);
CheckAndAddChild(context, 1, 2);
CheckAndAddChild(context, 2, 1);
CheckAndAddChild(context, 2, 2);
if (ensureOneParentHasNoChildren)
{
foreach (var child in context.Children.Where(x => x.ParentId == 3).ToArray())
{
context.Children.Remove(child);
}
context.SaveChanges();
}
else
{
CheckAndAddChild(context, 3, 2);
}
}
private static void CheckAndAddOtherParent(GroupJoinContext context, int id)
{
var otherParent = context.OtherParents.SingleOrDefault(x => x.Id == id);
if (otherParent == null)
{
otherParent = new OtherParent()
{
Name = "Other Parent" + id
};
context.OtherParents.Add(otherParent);
context.SaveChanges();
}
}
private static void CheckAndAddParent(GroupJoinContext context, int id)
{
var parent = context.Parents.SingleOrDefault(x => x.Id == id);
if (parent == null)
{
parent = new Parent
{
Name = "Parent" + id
};
context.Parents.Add(parent);
context.SaveChanges();
}
}
private static void CheckAndAddChild(GroupJoinContext context, int parentId, int otherParentId)
{
var child = context.Children.SingleOrDefault(x => x.ParentId == parentId && x.OtherParentId == otherParentId);
if (child == null)
{
child = new Child
{
ParentId = parentId,
OtherParentId = otherParentId
};
context.Children.Add(child);
context.SaveChanges();
}
}
static void Main(string[] args)
{
var dbContextBuilder = new DbContextOptionsBuilder <GroupJoinContext>();
dbContextBuilder.UseSqlServer("Server=.;Initial Catalog=EFCoreGroupJoin;Integrated Security=true;");
using (var context = new GroupJoinContext(dbContextBuilder.Options))
{
bool ensureOneParentHasNoChildren = false;
if (args.Length > 0 && args[0] == "-d")
{
ensureOneParentHasNoChildren = true;
}
InitialiseData(context, ensureOneParentHasNoChildren);
//var preCalcChildren = context.Children.Select(x => new
//{
// ParentId = x.ParentId,
// OtherParent = x.OtherParent.Name
//}).ToList();
//var results = context.Parents.GroupJoin(
// preCalcChildren,
// p => p.Id,
// c => c.ParentId,
// (parent, child) => new
// {
// ParentId = parent.Id,
// ParentName = parent.Name,
// Children = child.Select(x => x.OtherParent)
// });
//var results = context.Parents.GroupJoin(
// context.Children,
// p => p.Id,
// c => c.ParentId,
// (parent, child) => new
// {
// ParentId = parent.Id,
// ParentName = parent.Name,
// Children = child.Select(x => x.OtherParent.Name)
// });
var results = context.Parents.GroupJoin(
context.Children.Select(x => new
{
ParentId = x.ParentId,
OtherParent = x.OtherParent.Name
}),
p => p.Id,
c => c.ParentId,
(parent, child) => new
{
ParentId = parent.Id,
ParentName = parent.Name,
Children = child.Select(x => x.OtherParent)
});
foreach (var parent in results)
{
Console.WriteLine(parent.ParentName);
foreach (var parentChild in parent.Children)
{
Console.Write("-");
Console.WriteLine(parentChild);
}
}
}
Console.WriteLine("Press a key");
Console.ReadKey();
}
private static void DeleteOneChild(GroupJoinContext context)
{
}
