I have the following entity:
public class Module
{
public Module()
{
SubModules = new List<Module>();
}
public int Id { get; set; }
public string Title { get; set; }
public string Action { get; set; }
public string Controller { get; set; }
public string Icon { get; set; }
public List<Module> SubModules { get; set; }
}
Which, when initialised through Code First generates the following table Schema:
CREATE TABLE [dbo].[Modules](
[Id] [int] IDENTITY(1,1) NOT NULL,
[Title] [nvarchar](max) NULL,
[Action] [nvarchar](max) NULL,
[Controller] [nvarchar](max) NULL,
[Icon] [nvarchar](max) NULL,
[Module_Id] [int] NULL,
CONSTRAINT [PK_dbo.Modules] PRIMARY KEY CLUSTERED
(
[Id] ASC
)WITH (STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF)
)
GO
ALTER TABLE [dbo].[Modules] WITH CHECK ADD CONSTRAINT [FK_dbo.Modules_dbo.Modules_Module_Id] FOREIGN KEY([Module_Id])
REFERENCES [dbo].[Modules] ([Id])
GO
ALTER TABLE [dbo].[Modules] CHECK CONSTRAINT [FK_dbo.Modules_dbo.Modules_Module_Id]
GO
The problem is that when I populate this table with a parent module (Module_Id of null) and two child modules (Module_Id of the parent Module) and query the DBContext's collection of Modules, I get the parent module with it's collection of child modules correctlly, but I also get the child modules returned by themselves.
So the Modules collection in the DbContext looks a bit like this:
ParentModule
---Child Module
---Child Module
Child Module
Child Module
What I need is for those two Child Modules to not be returned as Modules in their own right, but only as the children of the parent.
Hope I've explained this ok.
I would add a ParentModuleId property (int?) to your Module class.
public class Module
{
public Module()
{
SubModules = new List<Module>();
}
public int Id { get; set; }
public string Title { get; set; }
public string Action { get; set; }
public string Controller { get; set; }
public string Icon { get; set; }
public int? ParentModuleId { get; set; }
[ForeignKey("ParentModuleId")]
public virtual ICollection<Module> SubModules { get; set; }
}
Notice how I have also added a ForeignKey attribute to the SubModules list to ensure that the new ParentModuleId property is used as the foreign key column.
This way you can manually check for the presence of a parent module.
You can then get the "root modules" like this:
var rootModules = context.Modules.Where(x => x.ParentModuleId == null);
If you need that a lot, you can also create an extension method:
public IQueryable<Module> WithoutParent(this IQueryable<Module> modules)
{
return modules.Where(x => x.ParentModuleId == null);
}
var rootModules = context.Modules.WithoutParent();
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments