I can't find way to add a unique constraint to my field with using attribute:
public class User
{
[Required]
public int Id { get; set; }
[Required]
// [Index("IX_FirstAndSecond", 2, IsUnique = true)] not supported by core
public string Email { get; set; }
[Required]
public string Password { get; set; }
}
I'm using these packages:
"Microsoft.EntityFrameworkCore": "1.0.1",
"Microsoft.EntityFrameworkCore.SqlServer": "1.0.1",
"Microsoft.EntityFrameworkCore.SqlServer.Design": "1.0.1",
"Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final",
On EF core you cannot create Indexes using data annotations.But you can do it using the Fluent API.
Like this inside your {Db}Context.cs
:
protected override void OnModelCreating(ModelBuilder builder)
{
builder.Entity<User>()
.HasIndex(u => u.Email)
.IsUnique();
}
...or if you're using the overload with the buildAction:
protected override void OnModelCreating(ModelBuilder builder)
{
builder.Entity<User>(entity => {
entity.HasIndex(e => e.Email).IsUnique();
});
}
You can read more about it here : Indexes
Also if you want to create Unique constrains on multiple columns you can simply do this (following @Sampath's link)
class MyContext : DbContext
{
public DbSet<Person> People { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Person>()
.HasIndex(p => new { p.FirstName, p.LastName })
.IsUnique(true);
}
}
public class Person
{
public int PersonId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
Since Entity Framework Core (EF Core) 5.0 we can configure Unique Indexes via Data Annotations.
It is little different to e.g. EF6, because we cannot set it on the property itself but instead on the class.
[Index(nameof(EmailAddress), IsUnique = true)]
public class User
{
[Key]
public Guid Id { get; set; }
[Required]
public string FullName { get; set; }
[Required]
public string EmailAddress { get; set; }
}
For further information on Indexes and Data Annotations see: https://docs.microsoft.com/en-us/ef/core/modeling/indexes?tabs=data-annotations
Index
attribute is on namespace Microsoft.EntityFrameworkCore
and requires the Microsoft.EntityFrameworkCore
nuget package. I had the models and DbContext on separate projects, and was having a hard time finding it thinking it was on System.ComponentModel.DataAnnotations
(it's not).
Solution for EF Core
public class User
{
public int Id { get; set; }
public string Name { get; set; }
public string Passport { get; set; }
}
public class ApplicationContext : DbContext
{
public DbSet<User> Users { get; set; }
public ApplicationContext()
{
Database.EnsureCreated();
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=efbasicsappdb;Trusted_Connection=True;");
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().HasAlternateKey(u => u.Passport);
//or: modelBuilder.Entity<User>().HasAlternateKey(u => new { u.Passport, u.Name})
}
}
DB table will look like this:
CREATE TABLE [dbo].[Users] (
[Id] INT IDENTITY (1, 1) NOT NULL,
[Name] NVARCHAR (MAX) NULL,
[Passport] NVARCHAR (450) NOT NULL,
CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED ([Id] ASC),
CONSTRAINT [AK_Users_Passport] UNIQUE NONCLUSTERED ([Passport] ASC)
);
If you just want to enforce uniqueness of a column then you want a unique index rather than an alternate key. In EF, alternate keys provide greater functionality than unique indexes because they can be used as the target of a foreign key.
Ef core support unique configuration.
protected override void OnModelCreating(ModelBuilder builder)
{
builder.Entity<Account>()
.HasIndex(account => account.Email)
.IsUnique();
}
Ef core support multiple unique keys
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Account>()
.HasKey(account => new { account.Id, account.Email, account.RoleId });
}
Don't forget run ef core command to make migration and update the database
>> dotnet ef migrations add MigrationName -c YourDbContextName
>> dotnet ef database update -c YourDbContextName
To use it in EF core via model configuration
public class ApplicationCompanyConfiguration : IEntityTypeConfiguration<Company>
{
public void Configure(EntityTypeBuilder<Company> builder)
{
builder.ToTable("Company");
builder.HasIndex(p => p.Name).IsUnique();
}
}
The OP is asking about whether it is possible to add an Attribute to an Entity class for a Unique Key. The short answer is that it IS possible, but not an out-of-the-box feature from the EF Core Team. If you'd like to use an Attribute to add Unique Keys to your Entity Framework Core entity classes, you can do what I've posted here
public class Company
{
[Required]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid CompanyId { get; set; }
[Required]
[UniqueKey(groupId: "1", order: 0)]
[StringLength(100, MinimumLength = 1)]
public string CompanyName { get; set; }
[Required]
[UniqueKey(groupId: "1", order: 1)]
[StringLength(100, MinimumLength = 1)]
public string CompanyLocation { get; set; }
}
For someone who is trying all these solution but not working try this one, it worked for me
protected override void OnModelCreating(ModelBuilder builder)
{
builder.Entity<User>().Property(t => t.Email).HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute("IX_EmailIndex") { IsUnique = true }));
}
None of these methods worked for me in .NET Core 2.2 but I was able to adapt some code I had for defining a different primary key to work for this purpose.
In the instance below I want to ensure the OutletRef field is unique:
public class ApplicationDbContext : IdentityDbContext
{
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Outlet>()
.HasIndex(o => new { o.OutletRef });
}
}
This adds the required unique index in the database. What it doesn't do though is provide the ability to specify a custom error message.
We can add Unique key index by using fluent api. Below code worked for me
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().Property(p => p.Email).HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute("IX_EmailIndex") { IsUnique = true }));
}
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HasAlternateKey