I like to create a DB model in ASP.Net Core 3.1. I am using Code First approach with EF Core 3.1.
I like to create a model for this relationship-
So, there is one Employee table and every employee has multiple bosses and each has multiple sub-ordinates. But every boss and every subordinate are employees also. What I have done is something like this-
Employee Model-
public class Employee
{
[HiddenInput(DisplayValue = false), Display(Name = "ID")]
[Key()]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Column(Order = 1)]
public Guid? Id { get; set; } = Guid.NewGuid();
[Column("Name"), Required(ErrorMessage = "Term Name should be given"), Display(Name = "Term Name", Prompt = "Please Give Term Name")]
[DataType(DataType.Text)]
public string Name { get; set; }
public ICollection<Boss> Bosses { get; set; }
public ICollection<Subordinate> Subordinates { get; set; }
............
............
}
But I am getting this error during creating the DB model by the command Add-Migration <MigrationName>-
Unable to determine the relationship represented by navigation property 'Employee.Bosses' of type 'ICollection'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.
Can anyone please help?
direct many-to-many relations are not supported with ef core 3.1.
See this: https://learn.microsoft.com/de-de/ef/core/what-is-new/ef-core-5.0/whatsnew
If you cannot use ef core >= 5, than you have to create a navigation property to the EmployeeBoss entity.
Try this:
public partial class Employee
{
public Employee()
{
EmployeeBossEmployees = new HashSet<EmpoyeeBoss>();
EmployeeBossBosses = new HashSet<EmpoyeeBoss>();
}
[Key]
public int Id { get; set; }
[InverseProperty(nameof(EmpoyeeBoss.Employee))]
public virtual ICollection<EmpoyeeBoss> EmployeeBossEmployees { get; set; }
[InverseProperty(nameof(EmpoyeeBoss.Boss))]
public virtual ICollection<EmpoyeeBoss> EmployeeBossBosses { get; set; }
}
public partial class EmpoyeeBoss
{
[Key]
public int Id { get; set; }
public int BossId { get; set; }
public int EmployeeId { get; set; }
[ForeignKey(nameof(EmployeeId))]
[InverseProperty("EmployeeBossEmployees")]
public virtual Employee Employee { get; set; }
[ForeignKey(nameof(BossId))]
[InverseProperty("EmployeeBossBosses")]
public virtual Employee Boss { get; set; }
}
and include in your dbcontext:
public virtual DbSet<Employee> Employees { get; set; }
public virtual DbSet<EmpoyeeBoss> EmployeeBosses { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<EmpoyeeBoss>(entity =>
{
entity.HasOne(d => d.Employee)
.WithMany(p => p.EmployeeBossEmployees)
.HasForeignKey(d => d.EmployeeId)
.OnDelete(DeleteBehavior.ClientSetNull);
entity.HasOne(d => d.Boss)
.WithMany(p => p.EmployeeBossBosses)
.HasForeignKey(d => d.BossId);
});
Related
Having the following parent class:
[Table("smart_recharge_registro")]
public class SmartRechargeRegistro
{
[Key]
public int id { get; set; }
public SmartRechargeRequest request { get; set; }
public SmartRechargeProceso proceso { get; set; }
public SmartRechargeResponse response { get; set; }
}
Which in turn references the following child classes:
[Table("smart_recharge_request")]
public class SmartRechargeRequest
{
public String nombreDeUsuario { get; set; }
public String passwordDeUsuario { get; set; }
public String msisdnSuscriptor { get; set; }
}
and:
[Table("smart_recharge_proceso")]
public class SmartRechargeProceso
{
[Key]
public int id { get; set; }
public String carrierId { get; set; }
public String cliente { get; set; }
public String network { get; set; }
}
and lastly:
[Table("smart_recharge_response")]
public class SmartRechargeResponse
{
public Boolean responseSuccess { get; set; }
public int responseCode { get; set; }
public String? responseDetails { get; set; }
}
The Add-Migration and Update-Database command execute without problems. However, when I try to save
await _repository.RegistroColeccion.AddAsync(registro);
await _repositorio.SaveChangesAsync();
I get the following error:
Microsoft.EntityFrameworkCore.DbUpdateException: Could not save changes. Please configure your entity type accordingly.
---> MySql.Data.MySqlClient.MySqlException (0x80004005): Cannot add
or update a child row: a foreign key constraint fails
(beservicebroker_dev.registro_eventos_srdotnet, CONSTRAINT
FK_registro_eventos_srdotnet_SmartRechargeProceso_procesoid FOREIGN
KEY (procesoid) REFERENCES smartrechargeproceso (id) O)
To solve the problem, I tried to create one-to-one relationships following this tutorial
modelBuilder.Entity<SmartRechargeRegistro>()
.HasOne(s => s.request)
.WithOne(r => r.SmartRechargeRegistro)
.HasForeignKey<SmartRechargeRequest>(r => r.id);
modelBuilder.Entity<SmartRechargeRegistro>()
.HasOne(s => s.proceso)
.WithOne(p => p.SmartRechargeRegistro)
.HasForeignKey<SmartRechargeProceso>(p => p.id);
modelBuilder.Entity<SmartRechargeRegistro>()
.HasOne(s => s.response)
.WithOne(r => r.SmartRechargeRegistro)
.HasForeignKey<SmartRechargeResponse>(r => r.id);
Inside SmartRechargeRequest, SmartRechargeProceso and SmartRechargeResponse, added the following:
[JsonIgnore]
public SmartRechargeRegistro SmartRechargeRegistro { get; set; }
Also added inside SmartRechargeRequest and SmartRechargeResponse an id
[Key]
public int id { get; set; }
I'm still unable to test the endpoint because the SmartRechargeRequest and SmartRechargeResponse are completely disfigured in the swagger (even if the [JsonIgnore] or [IgnoreDataMember] annotations are set) due to the presence of that SmartRechargeRegistro object.
I'm pretty sure my solution is misguided and I'm getting the process completely wrong.
What would be the proper way to map one-to-one relationships for this case? Any help will be appreciated.
Please note that in reality, these classes are huge (dozens of properties), so it's not possible to merge all of them on a single table.
I have a web api where I am trying to get sum and count of a related table. Using .net core 3 and EF Core 3.1.8.
This is what I have tried:
_context.Books
.Include(r => r.BookCategories)
.Include(r => r.Resources)
.Include(r => r.Ratings.GroupBy(g => g.Bookid).Select(s => new { SumAllVotes = s.Sum(item => item.Rating) }))
.ToListAsync();
But I just get an error message. (see below).
I find it difficault debugging with EF Core as I dont know where it is going wrong. Have been trying a couple of hours, but whatever I write I get the same error message.
Thought maybe you guys were able to see what was wrong.
What I want
I am trying to get Sum of all Rating inside table Ratings.
Rating contains only 0 or 1. And I am trying to sum ratings on each bookid. I wanted to have it in this class public int SumAllVotes { get; set; }.
Because I list out all Books...and one of the properties will then be SumAllVotes. (And also CountAllVotes, when I have finished this problem).
By the end I will have a SumAllVotes and CountAllVotes and can calculate the percentage of how many have pressed "1".
Error message:
An unhandled exception occurred while processing the request.
InvalidOperationException: Lambda expression used inside Include is
not valid.
Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.ProcessInclude(NavigationExpansionExpression
source, Expression expression, bool thenInclude)
What I have tried:
[HttpGet]
public async Task<ActionResult<IEnumerable<Books>>> GetBooks()
{
Guid userid = Guid.Parse(this.User.FindFirst(ClaimTypes.NameIdentifier).Value);
return await _context.Books
.Include(r => r.BookCategories)
.Include(r => r.Resources)
.Include(r => r.Ratings.GroupBy(g => g.Bookid).Select(s => new { SumAllVotes = s.Sum(item => item.Rating) }))
.ToListAsync();
}
Books and Ratings are defined as -
public partial class Books
{
public Books()
{
Bookmarks = new HashSet<Bookmarks>();
Comments = new HashSet<Comments>();
Favourites = new HashSet<Favourites>();
BookCategories = new HashSet<BookCategories>();
Resources = new HashSet<Resources>();
Ratings = new HashSet<Ratings>();
}
public int Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public byte Scaleoffun { get; set; }
public byte Scaleoflearning { get; set; }
public int? Goal { get; set; }
public int? Secondgoal { get; set; }
public int? Thirdgoal { get; set; }
public int? Subjectid { get; set; }
public int? Categoryid { get; set; }
public string Language { get; set; }
public string Estimatedtime { get; set; }
public string Image { get; set; }
public int? File { get; set; }
public int? Ownerid { get; set; }
public DateTime Createdon { get; set; }
public DateTime? Lastmodifiedon { get; set; }
public string Active { get; set; }
public string Url { get; set; }
public Guid Userid { get; set; }
public byte? Grade { get; set; }
[NotMapped]
public int SumAllVotes { get; set; }
[NotMapped]
public int CountAllVotes { get; set; }
public virtual Categories Category { get; set; }
public virtual Curriculum GoalNavigation { get; set; }
public virtual Users Owner { get; set; }
public virtual Curriculum SecondgoalNavigation { get; set; }
public virtual Subjects Subject { get; set; }
public virtual Curriculum ThirdgoalNavigation { get; set; }
public virtual ICollection<Bookmarks> Bookmarks { get; set; }
public virtual ICollection<Comments> Comments { get; set; }
public virtual ICollection<Favourites> Favourites { get; set; }
public virtual ICollection<BookCategories> BookCategories { get; set; }
public virtual ICollection<Resources> Resources { get; set; }
public virtual ICollection<Ratings> Ratings { get; set; }
}
public partial class Ratings
{
public int Id { get; set; }
public int? Bookid { get; set; }
public string Type { get; set; }
public Int16? Rating { get; set; }
public Guid Userid { get; set; }
public string Subject { get; set; }
public DateTime Createdon { get; set; }
public DateTime? Modifiedon { get; set; }
public byte? Active { get; set; }
public virtual Books Book { get; set; }
//public virtual Users User { get; set; }
}
These are some other solutions I have tried, but got the same error message:
.Include(r=> r.Ratings.Sum(i=>i.Rating))
and
.Include(r => new { m = r.Ratings.GroupBy(g => g.Bookid) })
You don't need to group child entities by parent's Id. When you Include one-to-many child entities, they are added to their parent's child list, and hence grouped by their parent's identity, based on the relationship between them. All you need to do is tell EF what values you want from that child list.
Change your query to -
_context.Books
.Include(r => r.BookCategories)
.Include(r => r.Resources)
.Include(r => r.Ratings)
.Select(p => new
{
// set ALL the primitive properties from Books entity
Id = p.Id,
Title = p.Title,
// etc ...
// set the computed properties
CountAllVotes = p.Ratings.Count,
SumAllVotes = p.Ratings.Sum(x => x.Rating)
// set the related entities
BookCategories = p.BookCategories,
Resources = p.Resources
})
.ToListAsync();
AutoMapper has a ProjectTo method that generates the required query and does the projection (the Select part) automatically. You can use that to avoid the hassle of setting all those properties manually.
I suggest you don't use Include with Select. Read article how to make queries with Projection (Select). Note, that Rating.Rating is nullable and you need to handle this. Here is a possible code sample:
var view = await _context.Books
.Where(your condition)
.Select(item => new
{
//Todo: fill other props
SumAllVotes = item.Ratings.Sum(rating => (Int16?) rating.Rating),
CountAllVotes = item.Ratings.Count,
})
.ToListAsync()
I get empty migration builder when I change a class name in EF core.
In older EFs , it usually auto generate the code for renaming tables.
But not working in EF core
public class EventComment : Comment
{
[Key]
public int CommentID { get; set; }
public int? ParentID { get; set; }
public virtual EventComment Parent { get; set; }
public int EventID { get; set; }
public virtual EventMaster EventMaster { get; set; }
}
public class Comment
{
public string CommentTitle { get; set; }
public string CommentDetails { get; set; }
public int UpVoteCount { get; set; }
public int DownVoteCount { get; set; }
public int CommentEmotion { get; set; }
public string CommentedByID { get; set; }
public virtual ApplicationUser ApplicationUser { get; set; }
}
now changing EventComment to CommentMaster. The migration is empty.
I use fluent API for configuring
builder.Entity<EventComment>()
.HasOne(e => e.EventMaster)
.WithMany()
.HasForeignKey(m => m.EventID);
builder.Entity<EventComment>()
.HasOne(e => e.ApplicationUser)
.WithMany()
.HasForeignKey(m => m.CommentedByID);
builder.Entity<EventComment>()
.HasOne(e => e.Parent)
.WithMany()
.HasForeignKey(x => x.ParentID);
This is because of the EF Core default table mapping convention (highlights are mine):
By convention, each entity will be setup to map to a table with the same name as the DbSet<TEntity> property that exposes the entity on the derived context. If no DbSet<TEntity> is included for the given entity, the class name is used.
I guess this is different from the previous EF. The essential part is that although you renamed the entity class, if you keep the old DbSet property name, the table name will not change.
How can I make many to many relation between AspNetRoles from Identity 3.0 and my custom table? I want simple 3 table, with both PermissionId and RoleId, something like AspNetUsersRole. I have something like this:
public class Permission
{
public int PermissionId { get; set; }
public string Name { get; set; }
public virtual ICollection<ApplicationRole> Roles { get; set; }
}
public class ApplicationRole : IdentityRole
{
public virtual ICollection<Permission> Permissions { get; set; }
}
But when I want to add migration, I got error:
Unable to determine the relationship represented by navigation property 'ApplicationRole.Permissions' of type 'ICollection<Permission>'. Either manually configure the relationship, or ignore this property from the model.
EF Core (EF7) does not currently support many to many relationship without a join entity. (Reference)
So, what you should do is to create an entity class for the join table and mapping two separate one-to-many relationships. Like;
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<PostTag>()
.HasKey(t => new { t.PostId, t.TagId });
modelBuilder.Entity<PostTag>()
.HasOne(pt => pt.Post)
.WithMany(p => p.PostTags)
.HasForeignKey(pt => pt.PostId);
modelBuilder.Entity<PostTag>()
.HasOne(pt => pt.Tag)
.WithMany(t => t.PostTags)
.HasForeignKey(pt => pt.TagId);
}
public class PostTag
{
public int PostId { get; set; }
public Post Post { get; set; }
public string TagId { get; set; }
public Tag Tag { get; set; }
}
Regarding to this question answer, it can be done more easily like this-
class Photo
{
public int Id { get; set; }
public ICollection<PersonPhoto> PersonPhotos{ get; set; }
}
class PersonPhoto
{
public int PhotoId { get; set; }
public Photo Photo { get; set; }
public int PersonId { get; set; }
public Person Person { get; set; }
}
class Person
{
public int Id { get; set; }
public ICollection<PersonPhoto> PersonPhotos{ get; set; }
}
Be sure to configure PersonPhoto with a composite key:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<PersonPhoto>().HasKey(x => new { x.PhotoId, x.PersonId });
}
To navigate, use a Select:
// person.Photos
var photos = person.PersonPhotos.Select(c => c.Photo);
Add This namespace-
using Microsoft.AspNetCore.Identity;
public class Permission
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int PermissionId { get; set; }
public string Name { get; set; }
public string UserIdFK { get; set; } //Foreign Key of Identity tbl
[ForeignKey("UserIdFK")]
public IdentityUser UserDetail { get; set; }
}
That's it, Happy coding :)
I'm quite new to EF, and I'm not really sure how to do this.
I have a many-to-many relationship, exactly like this:
When I try to add a resource (Recurso) to a profile (Perfil), I get the following error:
Invalid object name 'dbo.RecursoPerfils
Where the hell did RecursoPerfils come from?
How can I specify (preferably through attribute annotation) the table name for this relationship?
See the models below:
[Table("Perfil")]
public class Perfil
{
public Perfil()
{
this.Usuarios = new List<Usuario>();
this.Recursos = new List<Recurso>();
}
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int IdPerfil { get; set; }
[Required]
public string Descricao { get; set; }
public virtual ICollection<Usuario> Usuarios { get; set; }
public virtual ICollection<Recurso> Recursos { get; set; }
}
[Table("Recurso")]
public class Recurso
{
public Recurso()
{
this.Perfis = new List<Perfil>();
}
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int IdRecurso { get; set; }
[Required]
public string NomeRecurso { get; set; }
[Required]
public string Descricao { get; set; }
public virtual ICollection<Perfil> Perfis { get; set; }
}
You need to use Fluent API to configure the table name of the join table.
public class MyContext : DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Perfil>()
.HasMany(p => p.Recursos)
.WithMany(r => r.Perfis)
.Map(mc =>
{
mc.MapLeftKey("IdPerfil");
mc.MapRightKey("IdRecurso");
mc.ToTable("PerfilRecurso");
});
}
}
You can go through this Fluent API relationship mapping tutorial for more info