I am getting the following error when trying to run a query in EF.
A specified Include path is not valid. The EntityType 'InvestmentClub' does not declare a navigation property with the name 'ClubMembers'.
Query
return _context.InvestmentClubs.Where(x => x.InvestmentClubId == clubId)
.Include(x => x.Policies).Include(x => x.ClubMembers).FirstOrDefault();
Investmentclub class
public class InvestmentClub
{
public int InvestmentClubId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public int CreatedBy { get; set; }
public DateTime DateCreated { get; set; }
public InvestmentClubType ClubType { get; set; }
//Navigation properties
[ForeignKey("CreatedBy")]
public ApplicationUser ApplicationUser { get; set; }
public ICollection<InvestmentClubMember> ClubMembers;
public ICollection<InvestmentClubPolicy> Policies;
}
InvestmentClubPolicy class
public class InvestmentClubPolicy
{
public int InvestmentClubPolicyId { get; set; }
public int InvestmentClubId { get; set; }
public DateTime DateAdded { get; set; }
public string PolicyStatement { get; set; }
public AjoPolicyStatus PolicyStatus { get; set; }
public InvestmentClub InvestmentClub { get; set; }
}
I did not specify the properties as virtual as I didn't want eager loading of the related objects. Could this be the reason for the error? All help is eagerly anticipated.
public ICollection<InvestmentClubMember> ClubMembers;
should be
public virtual ICollection<InvestmentClubMember> ClubMembers { get; set; }
...or better yet,
public virtual ICollection<InvestmentClubMember> ClubMembers { get; protected set; }
It needs to be virtual in order for the dynamic proxy subclass to be able to populate the navigation property. They will not eager load automatically just because the property is virtual.
The .Include extension method is what does the eager loading.
ClubMembers is declared as a field, but EntityFramework requires it to be a property. Declare it as following:
public ICollection<InvestmentClubMember> ClubMembers { get; set; };
Related
I'm using EF core, and I have a many-to-many relationship between two entity
IotaProject <--> User
Here's entities & dto related to the question
public class IotaProject
{
[Key]
public int Id { get; set; }
[Required]
public string ProjectName { get; set; }
[Required]
public DateTime Create { get; set; }
public ICollection<ProjectOwnerJoint> Owners { get; set; } = new List<ProjectOwnerJoint>();
}
public class ProjectOwnerJoint
{
public int IotaProjectId { get; set; }
public IotaProject IotaProject { get; set; }
public int UserId { get; set; }
public User User { get; set; }
}
public class User
{
[Key]
public int Id { get; set; }
[Required]
public string FullName { get; set; }
[Required]
public string ShortName { get; set; }
[Required]
public string Email { get; set; }
public ICollection<ProjectOwnerJoint> OwnedProjects { get; set; } = new List<ProjectOwnerJoint>();
}
public class ApplicationDbContext : DbContext
{
public DbSet<IotaProject> IotaProjects { get; set; }
public DbSet<User> Users { get; set; }
public DbSet<ProjectOwnerJoint> ProjectOwnerJoint { get; set; }
}
public class IotaProjectDisplayDto
{
public int Id { get; set; }
public string ProjectName { get; set; }
public DateTime Create { get; set; }
public UserMinDto Owner { get; set; }
public int Count { get; set; }
public IEnumerable<UserMinDto> Reviewers { get; set; }
}
public class UserMinDto
{
public int Id { get; set; }
public string FullName { get; set; }
public string ShortName { get; set; }
}
Following LINQ is the problem, the LINQ purpose is to convert IotaProject to IotaProjectDisplayDto, and key part is that Owners property of IotaProject is ICollection and Owner property in IotaProjectDisplayDto is just one single element UserMinDto, so I only need to get the first element of IotaProject's Owners and that's FirstOrDefault() comes.
IEnumerable<IotaProjectDisplayDto> results = _db.IotaProjects.Select(x => new IotaProjectDisplayDto
{
Id = x.Id,
ProjectName = x.ProjectName,
Create = x.Create,
Owner = x.Owners.Select(y => y.User).Select(z => new UserMinDto { Id = z.Id, FullName = z.FullName, ShortName = z.ShortName }).FirstOrDefault()
});
return results;
it throws run-time exception
Expression of type 'System.Collections.Generic.List`1[ToolHub.Shared.iota.UserMinDto]' cannot be used for parameter
of type 'System.Linq.IQueryable`1[ToolHub.Shared.iota.UserMinDto]'
of method 'ToolHub.Shared.iota.UserMinDto FirstOrDefault[UserMinDto](System.Linq.IQueryable`1[ToolHub.Shared.iota.UserMinDto])' (Parameter 'arg0')
I'm guessing it's probably related to deferred execution, but after read some posts, I still can't resolve it.
Any tips would be appreciated.
Right now, the only way I can get this work is I change type of Owner property in IotaProjectDisplayDto into IEnumrable, which will no longer need FirstOrDefault() to immediate execution. And later on, I manually get the first element in the client to display.
This issue happened in Microsoft.EntityFrameworkCore.SqlServer 3.0.0-preview7.19362.6
I end up downgrade to EF core stable 2.2.6 as Ivan suggested in comment, and everything works fine.
I am trying to make a simple website that tracks students, programs, and classes. I've created the entities and I'm getting an error when trying to add the migration.
"The entity type 'Program' requires a primary key to be defined."
I have tried using the [Key] attribute and there is an Id field. The other table was created just fine. What else should I try?
Here is the problem class:
public class Program
{
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public bool UseRanks { get; set; }
}
Here is another table that I had no problems creating a migration for:
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string CellPhone { get; set; }
public string HomePhone { get; set; }
public string WorkPhone { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string State { get; set; }
public string ZipCode { get; set; }
public DateTime BirthDate { get; set; }
}
Here is what is in my ApplicationDbContext class:
public class ApplicationDbContext : IdentityDbContext
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
: base(options)
{
}
//public DbSet<Attendance> Attendances { get; set; }
public DbSet<Person> People { get; set; }
public DbSet<Bill> Bills { get; set; }
//public DbSet<Session> Sessions { get; set; }
public DbSet<Program> Programs { get; set; }
}
I've commented out the other entities because I was trying to add them one at a time. Trying to add a migration with all the entities resulted in the same error with the same specific class.
Complete shot in the dark, but based on the name of this class, I'm guessing you're referencing the wrong Program. Make sure that your DbSet<Program> is actually using your Program entity and not something like the Program class used at the console app level. You'll likely need to explicitly use the namespace, i.e. DbSet<MyApp.Models.Program>.
You might also consider changing the name of the class to remove any chance of ambiguity. There's some class names that are just going to wreck havoc trying to use them because they'll conflict with framework stuff constantly. It's usually more hassle than it's worth just to have that particular name. Program is one of those.
You can try to use this way:
public class Program
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public bool UseRanks { get; set; }
}
Adding [Key] attribute to the Id property.
In the file ApplicationDbContext.cs, you can override OnModelCreating method:
public DbSet<Program> Programs { get; set; }
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<Program>().ToTable("Programs").HasKey(x => x.Id);
}
I am trying to create navigation properties for two table.
Here is the code.
public class CourseMaster
{
public int Id { get; set; }
public string Name { get; set; }
public int? TeamLeaderId { get; set; }
[ForeignKey("TeamLeaderId")]
public StudentMaster TeamLeader { get; set; }
public int? GroupLeaderId { get; set; }
[ForeignKey("GroupLeaderId")]
public StudentMaster GroupLeader { get; set; }
public virtual ICollection<StudentMaster> Students { get; set; }
}
public class StudentMaster
{
public int id { get; set; }
public string Name { get; set; }
public int FirstSemCourseId { get; set; }
[ForeignKey("FirstSemCourseId")]
public CourseMaster FirstSemCourse { get; set; }
public int SecondSemCourseId { get; set; }
[ForeignKey("SecondSemCourseId")]
public CourseMaster SecondSemCourse { get; set; }
public int ThirdSemCourseId { get; set; }
[ForeignKey("ThirdSemCourseId")]
public CourseMaster ThirdSemCourse { get; set; }
public int CourseMasterId { get; set; }
public CourseMaster Course { get; set; }
}
// Fluent API
modelBuilder.Entity<StudentMaster>()
.HasOne(p => p.Course)
.WithMany(b => b.Students)
.HasForeignKey(p => p.CourseMasterId);
But when i am creating migrations i am getting following error.
Unable to determine the relationship represented by navigation property 'CourseMaster.TeamLeader' of the type 'StudentMaster'. Either manually configure the relationship, or ignore this property from model.
Whether the procedure i am following is right or should i create intermediate class.
or how should i create class.
Any help are appreciated.
Thanks
I have 2 classes
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
}
and
public class PersonWebsite
{
public int Id { get; set; }
public string Website { get; set; }
public int PersonId{ get; set; }
}
I've seen stuff like this being done before
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
public ICollection<PersonWebsite> PersonWebsites{ get; set; }
}
How could I go about implementing the code that when a Person is initialized, the PersonWebsites List will automatically be initialised and get all the PersonWebsite objects that have the same PersonId as the class that calls it.
Lazy Loading:
You can make PersonWebsites property virtual:
public virtual ICollection<PersonWebsite> PersonWebsites{ get; set; }
Entity framework will load it from the database as soon as it's required.
Also this method requires you to have lazy loading enabled which is by default:
DbContext.ContextOptions.LazyLoadingEnabled = true;
Eager Loading:
You can use include to force entity framework to load PersonWebsites on the first query:
DbSet.Include(p => p.PersonWebsites);
You may also want to change your PersonWebsite class like this, in order to navigate to the person from the PersonWebsite object (using Lazy-Loading):
public class PersonWebsite
{
public int Id { get; set; }
public string Website { get; set; }
[ForeignKey("Person")]
public int PersonId{ get; set; }
public virtual Person Person {get;set;}
}
I'm trying to eager load some child entities like so:
_context.Sites.Where(x => x.ID == siteID).Include(s => s.SiteLoggers).FirstOrDefault();
However, the error I am getting is:
A specified Include path is not valid. The EntityType 'MyProject.Dal.EF.Site' does not declare a navigation property with the name 'SiteLoggers'.
What is saying is correct, as MyProject.Dal.EF.Site does not exist, the object exists in MyProject.Domain.Entities.Site
What am I missing??? Thanks!
POCOs:
namespace MyProject.Domain.Entities
{
public class Site
{
public int ID { get; set; }
public int LocationID { get; set; }
public bool Active { get; set; }
public bool Deleted { get; set; }
public string Name { get; set; }
public virtual Location Location { get; set; }
public virtual IEnumerable<SiteLogger> SiteLoggers { get; set; }
}
}
namespace MyProject.Domain.Entities
{
public class SiteLogger
{
public int ID { get; set; }
public int UID { get; set; }
public int SiteID { get; set; }
public string Name { get; set; }
public int LocationID { get; set; }
public bool Active { get; set; }
public bool Deleted { get; set; }
public virtual Site Site { get; set; }
public virtual Location Location { get; set; }
}
}
You need to use ICollection instead of IEnumerable, because EF requires that your navigation properties are defined as ICollection<T>.
public virtual ICollection <SiteLogger> SiteLoggers { get; set; }