I recently needed to change the type of three properties in a model class from string to an ICollection custom type as shown below.
There are also three classes (SpecialType, TypeToAdd, TypeToRemove) that were added that have a primary key ID, name (string), qty (int) and a FK to corresponding Subscriptions_Regular_Id.
I ran the migration, then update-database to script, but when I ran the script in SSMS console it left off the three ICollection properties below. It did create the three dependent tables with their foreign keys back to the parent, but I can't understand why it's not creating these three ICollection properties. Something simple I'm overlooking I'm sure and wanted to get some input if anyone might have a suggestion.
public class Subscriptions
{
[Key]
public int Subscriptions_Regular_Id { get; set; }
public string CustomerNumber { get; set; }
public string Type { get; set; }
public int TypeQty { get; set; }
public ICollection<SpecialType> SpecialType { get; set; }
public ICollection<TypeToAdd> TypeToAdd { get; set; }
public ICollection<TypeToRemove> TypeToRemove { get; set; }
}
For context:
Subscriptions can have many SpecialTypes, TypeToAdd, and TypeToRemove
SpecialTypes, TypeToAdd, TypeToRemove can be tied to only one Subscription.
Thanks in advance for any input.
====== EDIT ======
Adding 3 ICollection classes:
public class TypeToAdd
{
[Key]
public int TypeToAddId { get; set; }
public string TypeToAdd { get; set; }
public int Qty { get; set; }
public int Subscriptions_Regular_Id { get; set; }
public Subscriptions Subscriptions { get; set; }
}
The other two classes are the same as above other than the first two property names (they are TypeToRemove and SpecialType).
but I can't understand why it's not creating these three ICollection properties
Collection Navigation Properties are implemented using seperate tables with foreign keys. Relational databases don't have multi-valued attributes, so that's just how related collections are implemented in an RDBMS.
Try to change the classes to this
public class Subscription
{
[Key]
public int Id { get; set; }
public string CustomerNumber { get; set; }
public string Type { get; set; }
public int TypeQty { get; set; }
[InverseProperty(nameof(TypeToAdd.Subscription))]
public ICollection<TypeToAdd> TypeToAdds { get; set; }
[InverseProperty(nameof(SpecialType.Subscription))]
public virtual ICollection<SpecialType> SpecialTypes { get; set; }
[InverseProperty(nameof(TypeToRemove.Subscription))]
public ICollection<TypeToRemove> TypeToRemoves { get; set; }
}
public class TypeToAdd
{
[Key]
public int Id { get; set; }
public string TypeToAdd { get; set; }
public int Qty { get; set; }
public int SubscriptionId { get; set; }
[ForeignKey(nameof(SubscriptionId))]
[InverseProperty("TypeToAdds")]
public virtual Subscription Subscription { get; set; }
}
SpecialType and TypeToRemove classes should be configured the same way as TypeToAdd.
Related
I'm studying EF6 and think I know quite a bit already, but couldn't find a good solution (yet) for this:
Suppose I have the following model classes:
class LivingRoom {
public int Id { get; set; }
public string Name { get; set; }
public PersonTypeId { get; set; }
public IList<Person> Persons { get; set; }
}
class Person {
public int Id { get; set; }
public int PersonTypeId { get; set; }
public string Name { get; set; }
}
With these model classes I'm able to save and load via DbContext without any problem. Thanks to the navigation property in the "parent" LivingRoom class, the Persons collection will be included in this process. I don't have to load/save them separately.
UPDATE: Forgot the logical PersonTypeId field which will be used for determining which Persons should be in the collection property.
So far so good.
But EF6 is creating a FK in the Persons table, pointing to the LivingRooms table, which seems logical.
But what if I'm going to use the Persons table for a lot more other parent entities, like eg. "Bus" and "Plane", and therefore don't want to have a dependency (= FK field in LivingRooms table) in the Persons table?
Can I achieve this (don't create the FK field) without breaking the "include child list" load/save process as described?
If yes, how? And if no, why not?
NB: Please understand that I want to learn the best techniques. So good advice, to not doing this, is also welcome.
First , it's better to handle FK in Person Table ourself to do that web have this :
class LivingRoom
{
public int Id { get; set; }
public string Name { get; set; }
public IList<Person> Persons { get; set; }
}
class Person
{
public int Id { get; set; }
public string Name { get; set; }
public LivingRoom LivingRoom { get; set; }
public int LivingRoomId { get; set; }
}
now If you have others Entities Like Bus and ... so we have
public class Bus
{
public int Id { get; set; }
public ICollection<Person> People { get; set; }
}
and Updated Person class is :
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public LivingRoom LivingRoom { get; set; }
public int LivingRoomId { get; set; }
public Bus Bus{ get; set; }
public int BusId { get; set; }
}
you can set FK in Person Table as Nullable to do this :
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public LivingRoom LivingRoom { get; set; }
public int? LivingRoomId { get; set; }
public Bus Bus{ get; set; }
public int? BusId { get; set; }
}
As you can see We set BusId and LivingRoomId as nullable or you can just set one of them that you want
Note : You need to add some mapper to tell EF which field id FK and something like this ,...
Very simple question but it looks like I'm trying to implement a simple one-to-many relationship between two models.
So far, what I have is this :
A product class :
public class Products
{
public long Id { get; set; }
public long Code { get; set; }
public DateTime DateCreated { get; set; }
public DateTime DateModified { get; set; }
public Boolean Reviewed { get; set; }
[ForeignKey("BundleId")]
public int BundleId { get; set; }
public virtual Bundles Bundle { get; set; }
}
And the Defects class looks like this:
public class Defects
{
public long Id { get; set; }
public String Description { get; set; }
public String Picture { get; set; }
public DateTime DateCreated { get; set; }
[ForeignKey("ProductId")]
public int ProductId { get; set; }
public Products Product { get; set; }
[ForeignKey("UserId")]
public int UserId { get; set; }
public virtual Users User { get; set; }
}
I thought that I did not need to add an ICollection of Defects to the Products class because it's a "simple" one-to-many relationship and this code would be enought to be able to get the ID of a Product in the Defects class (I don't need more).
But, of course I get an exception :
The property 'ProductId' cannot be configured as a navigation property. The property must be a valid entity type and the property should have a non-abstract getter and setter
How may I solve that issue ?
I might be doing someting wrong with my two foreign keys but since I declared the name of the foreign keys, I assumed it would have been enought.
Thanks for your attention.
This is what your relationship can be distilled to.
Please note that ForeignKey annotation is applied to navigation property with the name of the key property.
If you build one-to-many relationship - then ICollection is absolutely necessary. Otherwise where's the "many"
public class Products
{
public int Id { get; set; }
public virtual List<Defects> Bundle { get; set; }
}
public class Defects
{
public long Id { get; set; }
public int ProductId { get; set; }
[ForeignKey("ProductId")]
public Products Product { get; set; }
}
FK can also be applied to the key property. But in that case you have to put the name of the instance of related class there
public class Defects
{
public long Id { get; set; }
[ForeignKey("Product")]
public int ProductId { get; set; }
public Products Product { get; set; }
}
I am getting the weirdest error. I'm using code first to initial my database. I have 2 entities that have a many to many relationship. If I attempt to initialize either ICollection in the constructor I get the following error when trying trying to use the context to add a value (initially build the database vie entity framework)
The number of members in the conceptual type 'ClubCraftManager.DataAccess.Club' does not match with the number of members on the object side type 'ClubCraftManager.Model.Models.Club'. Make sure the number of members are the same.
public class Club
{
public Club()
{
this.ClubCrafters = new List<Crafter>();
}
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public virtual Guid ClubIdGuidId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public bool IsActive { get; set; }
public Guid ClubMangerId { get; set; }
[ForeignKey("ClubMangerId")]
public virtual Crafter ClubManager { get; set; }
public virtual ICollection<Crafter> ClubCrafters { get; }
}
If I leave the classes as the following no error, but I hate not initialing Collections and or lists, leaves yourself open for null values later on....
public class Club
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public virtual Guid ClubIdGuidId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public bool IsActive { get; set; }
public Guid ClubMangerId { get; set; }
[ForeignKey("ClubMangerId")]
public virtual Crafter ClubManager { get; set; }
public virtual ICollection<Crafter> ClubCrafters { get; set; }
}
Any idea what's going on here...?
I have struggling to get ICollection value in entity framework. I am using version 6.
Class Navigation_Functions
[Table("Navigation_Functions")]
public class Navigation_Functions
{
public Navigation_Functions()
{}
[Key]
public int Function_ID { get; set; }
[StringLength(250)]
[Required(ErrorMessage = "Required Title")]
[Display(Name = "Function Title")]
public string FunctionName { get; set; }
[Required(ErrorMessage = "Required Hierarchy Level")]
[Display(Name = "Hierarchy Level")]
public int Hierarchy_Level { get; set; }
public ICollection<Navigation_FunctionController> Navigation_FunctionController { get; set; }
}
Class Navigation_Controller
[Table("Navigation_FunctionController")]
public class Navigation_FunctionController
{
public Navigation_FunctionController()
{ }
[Key]
public int ControllerID { get; set; }
[StringLength(250)]
[Required]
public string ControllerName { get; set; }
public ICollection<Navigation_Functions> Navigation_Functions { get; set; }
}
Middle Class to break many-to-many relationship
[Table("Navigation_FunctionInController")]
public class Navigation_FunctionInController
{
public Navigation_FunctionInController()
{
}
[Key]
public int FunctionInController_ID { get; set; }
[Key]
[ForeignKey("Navigation_Functions")]
public int Function_ID { get; set; }
[Key]
[ForeignKey("Navigation_FunctionController")]
public int ControllerID { get; set; }
public Navigation_FunctionController Navigation_FunctionController { get; set; }
public Navigation_Functions Navigation_Functions { get; set; }
}
so when I run following code, I get all navigation_controller for navigation_function
public IEnumerable<Navigation_Functions> GetAllFunctions()
{
using(var _uow = new FunctionsNavigation_UnitOfWork())
{
var entities = _uow.Navigation_Functions_Repository.GetAll();
return entities.ToList();
}
}
I add virtual to model as
public virtual ICollection<Navigation_Functions> Navigation_Functions { get; set; }
public virtual ICollection<Navigation_FunctionController> Navigation_FunctionController { get; set; }
and I am getting following error to read data
You don't need to create the many to many relationship table, Entity framework will do that for you. All you need is to declare your properties as virtual, all use the include method.
more details here or here
Make sure to set ICollection method as "virtual"
e.g.
public virtual ICollection Courses { get; set; }
Here is an example:
http://www.entityframeworktutorial.net/code-first/configure-many-to-many-relationship-in-code-first.aspx
Keep in mind if the intersection table contains one or more properties (which are not part of the Primary Key), then don't create an intersection table, just use to ICollection in both entities. However, if there is one or more properties in the intersection, then create the intersection class. This is how the EF Designer works.
For a project at work I have created entities similar to the following:
public class ObjectA
{
public Guid ObjectAGUID { get; set; } // key
public string Name { get; set; }
public int Number { get; set; }
}
public class ObjectB
{
public Guid ObjectBGUID { get; set; } //key
public string Name { get; set; }
public int Number { get; set; }
}
public class Note
{
public Guid NoteGUID { get; set; } // key
public Guid AssociationGUID { get; set; }
public string Text { get; set; }
public string NoteType { get; set; }
}
Both ObjectA and ObjectB have a 1-Many relationship with Note where Note.AssociatedGUID is the dependent property to A and B's respective entity key. In other words, A and B can have any number Note entities associate with either one.
My problem:
When I create a new ObjectA and a new Note where Note.AssociatedGUID = ObjectA.ObjectAGUID , I get the following error on DBContext.SaveChanges():
Entities in 'Entities.Notes' participate in the 'ObjectBNote' relationship. 0 related 'ObjectB' were found. 1 'ObjectB' is expected.
Musings
If I want to have Notes for both ObjectA and ObjectB do I need to create separate Note entities,say NoteA and NoteB, to do this? If so this seems redundant.
Or, do I need to have a separate nullable foreign key on Note for each parent entity? While more manageable this seems a little overkill as well.
public class Note
{
public System.Guid NoteGUID { get; set; }
public System.Guid? ObjectAGUID { get; set; }
public System.Guid? ObjectBGUID { get; set; }
public string Text { get; set; }
public string NoteType { get; set; }
}
Help?