Entity Framework 6 GUID as primary key: Cannot insert the value NULL into column 'Id', table 'FileStore'; column does not allow nulls

I have an entity with primary key "Id" which is Guid:

public class FileStore
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string Path { get; set; }
}

And some configuration:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<FileStore>().Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
    base.OnModelCreating(modelBuilder);
}

When I try to insert a record I get a following error:

Cannot insert the value NULL into column 'Id', table 'FileStore'; column does not allow nulls. INSERT fails.\r\nThe statement has been terminated.

I don't want to generate Guid manually. I just want to insert a record and get Id generated by SQL Server. If I set .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity), Id column is not Identity column in SQL Server.

How can I configure Entity Framework to autogenerate Guid in SQL Server?

Solution 1:

In addition to adding these attributes to your Id column:

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }

in your migration you should change your CreateTable to add the defaultValueSQL property to your column i.e.:

Id = c.Guid(nullable: false, identity: true, defaultValueSql: "newsequentialid()"),

This will prevent you from having to manually touch your database which, as you pointed out in the comments, is something you want to avoid with Code First.

Solution 2:

try this :

public class FileStore
 {
   [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   public Guid Id { get; set; }
   public string Name { get; set; }
   public string Path { get; set; }
 }

You can check this SO post.

Solution 3:

You can set the default value of your Id in your db to newsequentialid() or newid(). Then the identity configuration of EF should work.

Solution 4:

This works for me (no Azure), SQL 2008 R2 on dev server or localdb\mssqllocaldb on local workstation. Note: entity adds Create, CreateBy, Modified, ModifiedBy and Version columns.

public class Carrier : Entity
{
    public Guid Id { get; set; }
    public string Code { get; set; }
    public string Name { get; set; }
}

then create a mapping configuration class

public class CarrierMap : EntityTypeConfiguration<Carrier>
{
    public CarrierMap()
    {
        HasKey(p => p.Id);

        Property(p => p.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        Property(p => p.Code)
            .HasMaxLength(4)
            .IsRequired()
            .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute { IsClustered = true, IsUnique = true }));

        Property(p => p.Name).HasMaxLength(255).IsRequired();
        Property(p => p.Created).HasPrecision(7).IsRequired();
        Property(p => p.Modified)
            .HasColumnAnnotation("IX_Modified", new IndexAnnotation(new IndexAttribute()))
            .HasPrecision(7)
            .IsRequired();
        Property(p => p.CreatedBy).HasMaxLength(50).IsRequired();
        Property(p => p.ModifiedBy).HasMaxLength(50).IsRequired();
        Property(p => p.Version).IsRowVersion();
    }
}

This creates an Up method in the initial DbMigration when you execute add-migration like this

        CreateTable(
            "scoFreightRate.Carrier",
            c => new
                {
                    Id = c.Guid(nullable: false, identity: true),
                    Code = c.String(nullable: false, maxLength: 4),
                    Name = c.String(nullable: false, maxLength: 255),
                    Created = c.DateTimeOffset(nullable: false, precision: 7),
                    CreatedBy = c.String(nullable: false, maxLength: 50),
                    Modified = c.DateTimeOffset(nullable: false, precision: 7,
                        annotations: new Dictionary<string, AnnotationValues>
                        {
                            { 
                                "IX_Modified",
                                new AnnotationValues(oldValue: null, newValue: "IndexAnnotation: { }")
                            },
                        }),
                    ModifiedBy = c.String(nullable: false, maxLength: 50),
                    Version = c.Binary(nullable: false, fixedLength: true, timestamp: true, storeType: "rowversion"),
                })
            .PrimaryKey(t => t.Id)
            .Index(t => t.Code, unique: true, clustered: true);

Note: that the Id columns does not get a default value, don't worry

Now execute Update-Database, and you should end up with a table definition in your database like this:

CREATE TABLE [scoFreightRate].[Carrier] (
    [Id]         UNIQUEIDENTIFIER   DEFAULT (newsequentialid()) NOT NULL,
    [Code]       NVARCHAR (4)       NOT NULL,
    [Name]       NVARCHAR (255)     NOT NULL,
    [Created]    DATETIMEOFFSET (7) NOT NULL,
    [CreatedBy]  NVARCHAR (50)      NOT NULL,
    [Modified]   DATETIMEOFFSET (7) NOT NULL,
    [ModifiedBy] NVARCHAR (50)      NOT NULL,
    [Version]    ROWVERSION         NOT NULL,
    CONSTRAINT [PK_scoFreightRate.Carrier] PRIMARY KEY NONCLUSTERED ([Id] ASC)
);


GO
CREATE UNIQUE CLUSTERED INDEX [IX_Code]
    ON [scoFreightRate].[Carrier]([Code] ASC);

Note: we have a overridden the SqlServerMigrationSqlGenerator to ensure it does NOT make the Primary Key a Clustered index as we encourage our developers to set a better clustered index on tables

public class OurMigrationSqlGenerator : SqlServerMigrationSqlGenerator
{
    protected override void Generate(AddPrimaryKeyOperation addPrimaryKeyOperation)
    {
        if (addPrimaryKeyOperation == null) throw new ArgumentNullException("addPrimaryKeyOperation");
        if (!addPrimaryKeyOperation.Table.Contains("__MigrationHistory"))
            addPrimaryKeyOperation.IsClustered = false;
        base.Generate(addPrimaryKeyOperation);
    }

    protected override void Generate(CreateTableOperation createTableOperation)
    {
        if (createTableOperation == null) throw new ArgumentNullException("createTableOperation");
        if (!createTableOperation.Name.Contains("__MigrationHistory"))
            createTableOperation.PrimaryKey.IsClustered = false;
        base.Generate(createTableOperation);
    }

    protected override void Generate(MoveTableOperation moveTableOperation)
    {
        if (moveTableOperation == null) throw new ArgumentNullException("moveTableOperation");
        if (!moveTableOperation.CreateTableOperation.Name.Contains("__MigrationHistory")) moveTableOperation.CreateTableOperation.PrimaryKey.IsClustered = false;
        base.Generate(moveTableOperation);
    }
}

Solution 5:

It happened to me before.

When the table has been created and I added in .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity) later, the code migration somehow could not assign default value for the Guid column.

The fix:

All we need is to go to the database, select the Id column and add newsequentialid() manually into Default Value or Binding.

No need to update dbo.__MigrationHistory table.

Hope it helps.

The solution of adding New Guid() is generally not preferred, because in theory there is possibility that you might get a duplicate accidentally.

And you shouldn't worry about directly editing in the database. All Entity Framework do is automate part of our database work.

Translating

.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)

into

[Id] [uniqueidentifier] NOT NULL DEFAULT newsequentialid(),

If somehow our EF missed one thing and did not add in the default value for us, just go ahead and add it manually.