Three tables are needed to be joined together.
Table [Package]
ID (int)
ContainerID (int)
Code (string)
Code2 (string)
Table [UserHasPackages]
UserID (Comes from Identity tables) (string)
PackageID (int)
Table [Container]
ID (int)
Name (string)
Description (string)
Into a viewmodel that represents an object I'd like to display in my view:
public class CustomViewModel
{
public int ID { get; set; }
public string Name { get; set; } // Container.Name
public string Code { get; set; } // Package.Code
public string Code2 { get; set; } // Package.Code2
}
But I'm having problems doing the join:
List<CustomViewModel> list = new List<CustomViewModel>();
list = context.Packages.Join(
context.Containers,
p => p.ContainerID,
c => c.ID,
(p, c) => new { p, c})
.Join( //error is here
context.UserHasPackages,
a => a.p.ID,
b => b.ApplicationUserId,
(a, b) => new { a, b })
.Select(f => new CustomViewModel
{
ID = f.p.ID,
Name = f.c.Name,
Code = f.p.Code,
Code2 = f.p.Code2
}).ToList();
Type arguments for method cannot be inherited from the usage. Try specifying the type arguments explicitly.
Is there another way to do two joins (as described) that's the more-proper way?
SOLUTION
Method based syntax is a no-go here, had to go with query syntax:
var query = (from package in context.Packages
join container in context.Containers on package.ContainerID equals container.ID
join userHasPackage in context.UserHasPackages on package.ID equals userHasPackage.PackageID
where userHasPackage.UserID == "SomeUser"
select new CustomViewModel
{
ID = package.ID,
Name = container.Name,
Code = package.Code,
Code2 = package.Code2
}).ToList();
I'm assuming that you want to join the UserHasPackages table because you wanted to filter the results for a specific user (I just put in a 'SomeUser' because I'm not sure where the 'UserHasPackages.ApplicationUserId' came from) since it is not included on the view model.
I believe something like the following should work:
var list = context.Packages
.Join(context.Containers, p => p.ContainerID, c => c.ID, (p, c) => new { p, c })
.Join(context.UserHasPackages, pc => pc.p.ID, u => u.PackageID, (pc, u) => new { pc.p, pc.c, u })
.Where(pcu => pcu.u.UserID == "SomeUser")
.Select(pcu => new
{
pcu.p.ID,
pcu.c.Name,
pcu.p.Code,
pcu.p.Code2
});
You could also do this using the query syntax:
var query = from package in context.Packages
join container in context.Containers on package.ContainerID equals container.ID
join userHasPackage in context.UserHasPackages on package.ID equals userHasPackage.PackageID
where userHasPackage.UserID == "SomeUser"
select new
{
package.ID,
container.Name,
package.Code,
package.Code2
};
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