I need help creating the relationship in entity framework as everything I have tried gives me errors when trying to add the migration or if I get passed that then I try to update the database and get an error about indexes with the same name.
public class Profile
{
public Profile()
{
Environments = new HashSet<Environment>();
}
[Key]
public int Id { get; set; }
public string VersionCreated { get; set; }
public string DiskLocation { get; set; }
public string Name { get; set; }
public DateTime DateTime { get; set; }
public virtual Product Product { get; set; }
public virtual Instance OriginalInstance { get; set; }
public virtual ICollection<Environment> Environments { get; set; }
}
public class Instance
{
public Instance()
{
TestResults = new HashSet<TestResult>();
Environments = new HashSet<Environment>();
}
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Version { get; set; }
public string UserFriendlyName { get; set; }
public virtual Product Product { get; set; }
public virtual Profile LastKnownProfile { get; set; }
public virtual Computer Computer { get; set; }
public virtual ICollection<TestResult> TestResults { get; set; }
public virtual ICollection<Environment> Environments { get; set; }
}
The problem with the above classes is that the OrginalInstance property on the Profile class and the LastKnownProfile in the Instance class are supposed to just be foreign keys to those specific tables and they probably won't be the same very often. They can also both possibly be null.
I have tried:
modelBuilder.Entity<Instance>().HasRequired(i => i.LastKnownProfile);
modelBuilder.Entity<Profile>().HasRequired(p => p.OriginalInstance);
This gave me an Unable to determine the principal end of an association between the types 'EcuWeb.Data.Entities.Instance' and 'EcuWeb.Data.Entities.Profile'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations. error.
and with:
modelBuilder.Entity<Instance>().HasRequired(i => i.LastKnownProfile).WithOptional();
modelBuilder.Entity<Profile>().HasRequired(p => p.OriginalInstance).WithOptional();
The database adds a foreign key reference back to itself.
...that the OrginalInstance property on the Profile class and the
LastKnownProfile in the Instance class are supposed to just be foreign
keys to those specific tables and they probably won't be the same very
often. They can also both possibly be null.
In this case you actually want two one-to-many relationships between Profile and Instance if I don't misunderstand your quote above. It would mean that many Profiles can have the same OriginalInstance and that many Instances can have the same LastKnownProfile. The correct mapping would look like this then:
modelBuilder.Entity<Profile>()
.HasOptional(p => p.OriginalInstance)
.WithMany()
.Map(m => m.MapKey("OriginalInstanceId"));
modelBuilder.Entity<Instance>()
.HasOptional(i => i.LastKnownProfile)
.WithMany()
.Map(m => m.MapKey("LastKnownProfileId"));
The lines with MapKey are optional. Without them EF will create a foreign key with a default name.
Also note that you must use HasOptional (instead of HasRequired) if "both can possibly be null".
Related
I have 3 entities: Person, User, and Location.
A Person can have multiple Locations
A User can have multiple Locations
My entities are set up as such:
public class Person
{
public Guid Id { get; set; }
public string Name { get; set; }
public virtual IList<Location>? Locations { get; set; }
}
public class PersonEntityTypeConfiguration : IEntityTypeConfiguration<Person>
{
public void Configure(EntityTypeBuilder<Person> builder)
{
builder
.HasMany(b => b.Locations)
.WithOne(b => b.Person)
.HasForeignKey(b => b.PersonId)
.IsRequired(false);
}
}
public class User
{
public Guid Id { get; set; }
public Guid? Username { get; set; }
public virtual IList<Location>? Locations { get; set; }
}
public class UserEntityTypeConfiguration : IEntityTypeConfiguration<User>
{
public void Configure(EntityTypeBuilder<User> builder)
{
builder
.HasMany(b => b.Locations)
.WithOne(b => b.User)
.HasForeignKey(b => b.UserId)
.IsRequired(false);
}
}
public class Location : UdbObject
{
public Guid Id { get; set; }
public string Description { get; set; }
[ForeignKey(nameof(Person))]
public Guid? PersonId { get; set; }
public virtual Person? Person { get; set; }
[ForeignKey(nameof(User))]
public Guid? UserId { get; set; }
public virtual User? User { get; set; }
}
Problem: I tried to insert a User into my SQL Server DB. This user has one Location object within its IList<Location>? Locations collection. I am getting the following error: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Locations_Persons_PersonId".
Here is where it is going wrong:
Since Person.Id is a Guid? object, it automatically gets set to the equivalent of Guid.Empty before it is submitted to the DB. This causes the FK conflict, since the DB sees that there is no Person object in the DB with an Id set to the equivalent of Guid.Empty.
What I've tried: I saw that in previous version of EF Core, there is a .WithOptional() method that can be used in the Fluent API, but unfortunately this method is not recognized in EF Core 7. I tried to use the .IsRequired(false) method in the API, and it probably works from the DB standpoint, but my problem is that the GUID-based Id property is being set to Guid.Empty on the server before being passed to the DB, so .IsRequired(false) doesn't have the opportunity to do its job.
Am I missing something? Is there some other way to configure this?
Solution: I had a PersonDto that had a property public Guid Id { get; set; } instead of Guid? and it was being mapped back to the Person object with Guid.Empty loaded in it. Duh.
Just make them M2M relationships and the foreign keys will all be in bridge tables. eg
public class Location : UdbObject
{
public Guid Id { get; set; }
public string Description { get; set; }
public virtual ICollection<Person> Persons { get; } = new HashSet<Person>();
public virtual ICollection<User> Users { get; } = new HashSet<User>();
}
I'm missing something when using the data annotations.
This is my first class
[Table("PriceFeed")]
public class PriceFeed : History
{
public PriceFeed()
{
this.Votes = new List<PriceVote>();
this.History = new List<PriceFeed__History>();
}
[Key]
public long Id { get; set; }
[ForeignKey("Store")]
public long Store_Id { get; set; }
[ForeignKey("Item")]
public long Item_Id { get; set; }
[Required]
public decimal Price { get; set; }
public Store Store { get; set; }
public Item Item { get; set; }
public virtual ICollection<PriceFeed__History> History { get; set; }
}
And this is my second class
[Table("PriceFeed__History")]
public class PriceFeed__History : History
{
[Key]
public long Id { get; set; }
[ForeignKey("PriceFeed")]
public long PriceFeed_Id { get; set; }
[Required]
public decimal Price { get; set; }
public virtual PriceFeed PriceFeed { get; set; }
}
When I run the add-migration, it creates the database correctly but when I try to access PriceFeed.History it gives me an error
{"Message":"An error has occurred.","ExceptionMessage":"A specified Include path is not valid. The EntityType 'Verdinhas.Web.Contexts.PriceFeed' does not declare a navigation property with the name 'PriceFeed__History'."
I always worked with API Fluent and typed by myself the code like
.Entity<Student>()
.HasRequired<Standard>(s => s.Standard)
.WithMany(s => s.Students)
.HasForeignKey(s => s.StdId);
But now I'm using the data annotations and when I generate the migration, it does not create the "withmany" like the above.
What am I doing wrong?
The issue has nothing to do with Data Annotations which seems to be correct in your model.
As mentioned in the comments, the exception is caused by a code that tries to use Include method with string "'PriceFeed__History" - you seem to think that you should specify the related entity types, but in fact you need to specify the navigation property names, which in your case is "History".
I have three classes
public class SPR
{
public int ID { get; set; }
public string SubmittedBy { get; set; }
public virtual ICollection<SPRItem> AllItems { get; set; }
}
public class SPRItem
{
[Key]
public int ID { get; set; }
public string manufacturer { get; set; }
[ForeignKey("SPRItemDetails")]
public virtual SPRItemDetails ItemDetails { get; set; }
public string requestedMinimumQuantity { get; set; }
public virtual SPR SPR { get; set; }
}
public class SPRItemDetails
{
public int ID { get; set; }
public string ItemNumber { get; set; }
public virtual SPRItem SPRItem { get; set; }
}
So the SPR class has a collection of SPRItem and which has the ItemDetails object.
I have a web API method which maps the data to the SPR object and fills in the SPRItem list and ItemDetails object. But whenever I am trying to save it using Entity Framework code first I am getting this error
{"Message":"An error has occurred.","ExceptionMessage":"Unable to determine the principal end of an association between the types 'SharePoint.MultiSPR.Service.Models.SPRItemDetails' and 'SharePoint.MultiSPR.Service.Models.SPRItem'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.
This is my Context
public System.Data.Entity.DbSet<SharePoint.MultiSPR.Service.Models.SPR> SPRs { get; set; }
public System.Data.Entity.DbSet<SharePoint.MultiSPR.Service.Models.SPRItem> SPRItem { get; set; }
public System.Data.Entity.DbSet<SharePoint.MultiSPR.Service.Models.SPRItemDetails> SPRItemDetails { get; set; }
Can someone please tell me how to configure the relations correctly.
Thanks
In a 1:1 relation you always have to indicate the principal and the dependent entity. The principal entity is the one that is most independent of the other, in this case SPRItem, presumably.
Next thing to decide is whether the relationship should be optional or required. I think, judging by the entity names, an SPRItemDetails will never exist without an SPRItem, so the relationship is 1:0..1 (not 0..1:0..1). Here's how to configure that:
modelBuilder.Entity<SPRItem>()
.HasOptional(si => si.ItemDetails)
.WithRequired(id => id.SPRItem);
This creates (or requires) an SPRItemDetails table having a primary key that's also a foreign key to SPRItem.
I get the following error when using Entity Framework:
Unable to determine the principal end of an association between the types
'xxx.Domain.Entities.UserSettings' and 'xxx.Domain.Entities.User'. The
principal end of this association must be explicitly configured using either
the relationship fluent API or data annotations.
Here are the two Entity classes:
public class User
{
[Key, Column("un")]
public string Username { get; set; }
public int Level { get; set; }
public virtual UserSettings UserSettings { get; set; }
}
public class UserSettings
{
[Key]
public string Username { get; set; }
public int ActiveRefresh { get; set; }
[ForeignKey("Username")]
public virtual User User { get; set; }
}
I am not sure how to resolve this error. I am stuck with the database design so I can't update that to fix the issue. Is there a way using Fluent Api to get these associations working?
A User can have a UserSettings object. This is the relationship that is desired.
It looks like you need a one to zero-or-one relationship
// Configure the primary key for the User
modelBuilder.Entity<User>()
.HasKey(t => t.Username);
// Map one-to-zero or one relationship
modelBuilder.Entity<UserSettings>()
.HasRequired(t => t.User)
.WithOptional(t => t.UserSettings);
This is not tested! Remove all the annotations from the entity classes. The link to Fluent API relationships in my comment above has more examples of the different kinds of relationship.
using anotations :
public class User
{
[Key, Column("un")]
public string Username { get; set; }
public int Level { get; set; }
//here is your foreign to UserSettings
public int? UserSettingsID{ get; set; }
[ForeignKey("UserSettingsID")] // not needed if you're using the '%ID' convention
//Navigation property
public virtual UserSettings UserSettings { get; set; }
}
public class UserSettings
{
//UserSettings PK
public int UserSettingsID{ get; set; }
public int ActiveRefresh { get; set; }
}
I assume here that you don't need to retrieve the user from his settings
I am using code first and EF 4.1 im my MVC3 App and have two models that have two
relationships between them. Here is the classes that refers to these models:
public class Cattle
{
public int CattleID { get; set; }
public int FarmID { get; set; }
public int SituationID { get; set; }
public int DiscardID { get; set; }
public int Stamp { get; set; }
public string Sex { get; set; }
public string Condition { get; set; }
public virtual Farm Farm { get; set; }
[InverseProperty("Cattles2")]
public virtual ICollection<Farm> Farms { get; set; }
}
public class Farm
{
public int FarmID { get; set; }
public string Name { get; set; }
public virtual ICollection<Cattle> Cattles { get; set; }
public virtual ICollection<Cattle> Cattles2 { get; set; }
}
One relationship is one to one or many cause a catle can only be in a farm and a farm can contains many catles. Another relationship is many to many that a catle can be transferred between farms and i would generate a third table to store the transfers using Fluent API. I also would like to insert a Date property to the new table and don´t know how to do it.Here is the code in the FarmContext inside the OnModelCreating method:
modelBuilder.Entity<Catle>()
.HasMany(c => c.Farms).WithMany(i => i.Catles)
.Map(t => t.MapLeftKey("CatleID")
.MapRightKey("FarmID")
.ToTable("CatleTransfer"));
When i build the project it seems to work fine and the generated tables Catle and Farm are fed by the FarmInitializer but some information that points to this relationship is missing in the index page of Catle. its appearing in blank to me. Here is the code that gets the information:
#Html.DisplayFor(modelItem => item.Farm.Name)
I need Knowing what i am doing wrong or if there is a more appropriate method to resolve that issue.
You may need to be specific about the relationship when dealing with multiple joins.
Try adding a Foreign Key attribute to your Farm navigation property.
[ForeignKey("FarmID")]
public virtual Farm Farm { get; set; }