Target Framework: .Net Core 2.1
EntityFrameworkCore: 2.1.4
I've encountered some behaviour I don't understand when calling SaveChanges()
. As the title says: I'm having valid GUIDs that have a Foreign Key relation with the same table being replaced with NULLs when inserting new records.
This is only happening for a specific column though, and only when EF generates the SQL for the changes made in the context. I can insert the same values fine inside SSMS.
For the purposes of demonstration I have created a minimal repository on GitHub that you can use to recreate the exact problem I'm encountering, but in a nutshell if you have an entity like this:
public class Account
{
[Key]
public Guid AccountId { get; set; }
#region Audit
public Guid? AddedByAccountId { get; set; }
public DateTime AddedOnUtc { get; set; }
public Guid? ModifiedByAccountId { get; set; }
public DateTime ModifiedOnUtc { get; set; }
#endregion Audit
#region Navigation Properties
[ForeignKey(nameof(AddedByAccountId))]
public virtual Account AddedByAccount { get; set; }
[ForeignKey(nameof(ModifiedByAccountId))]
public virtual Account ModifiedByAccount { get; set; }
#endregion Navigation Properties
}
And a derived DbContext implementation like this:
public class EntityFrameworkDbContext : DbContext
{
public EntityFrameworkDbContext(DbContextOptions<EntityFrameworkDbContext> options)
: base(options)
{
}
public DbSet<Account> Accounts { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Account>(entity =>
{
// For some reason this self referencing key generates a unique
// constraint in the migration script if we don't set this here.
// "ModifiedByAccountId" does not have this issue! I suspect this might
// the root cause of the NULL data issue.
entity.HasIndex(e => e.AddedByAccountId).IsUnique(false);
});
}
}
Inserting anything into the context should yield the same results. For example:
private void InitialiseDatabase()
{
var systemAccount = new Account
{
AccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
AddedByAccountId = null,
AddedOnUtc = DateTime.UtcNow,
ModifiedByAccountId = null,
ModifiedOnUtc = DateTime.UtcNow
};
var otherAccounts = new List<Account>
{
new Account
{
AccountId = Guid.Parse("015b76fc-2833-45d9-85a7-ab1c389c1c11"),
AddedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
AddedOnUtc = DateTime.UtcNow,
ModifiedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
ModifiedOnUtc = DateTime.UtcNow
},
new Account
{
AccountId = Guid.Parse("538ee0dd-531a-41c6-8414-0769ec5990d8"),
AddedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
AddedOnUtc = DateTime.UtcNow,
ModifiedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
ModifiedOnUtc = DateTime.UtcNow
},
new Account
{
AccountId = Guid.Parse("8288d9ac-fbce-417e-89ef-82266b284b78"),
AddedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
AddedOnUtc = DateTime.UtcNow,
ModifiedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
ModifiedOnUtc = DateTime.UtcNow
},
new Account
{
AccountId = Guid.Parse("4bcfe9f8-e4a5-49f0-b6ee-44871632a903"),
AddedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
AddedOnUtc = DateTime.UtcNow,
ModifiedByAccountId = Guid.Parse("35c38df0-a959-4232-aadd-40db2260f557"),
ModifiedOnUtc = DateTime.UtcNow
}
};
_dbContext.Add(systemAccount);
_dbContext.AddRange(otherAccounts);
try
{
_dbContext.SaveChanges();
}
catch (Exception ex)
{
// Just checking to see if anything was being raised.
}
}
Will generate the following SQL (captured using SQL Server Profiler and formatted for readability):
exec sp_executesql N'SET NOCOUNT ON;
INSERT INTO [Accounts]
(
[AccountId],
[AddedByAccountId],
[AddedOnUtc],
[ModifiedByAccountId],
[ModifiedOnUtc]
)
VALUES
(
@p5,
@p6,
@p7,
@p8,
@p9
),
(
@p10,
@p11,
@p12,
@p13,
@p14
),
(
@p15,
@p16,
@p17,
@p18,
@p19
),
(
@p20,
@p21,
@p22,
@p23,
@p24
);
',N'@p5 uniqueidentifier,
@p6 uniqueidentifier,
@p7 datetime2(7),
@p8 uniqueidentifier,
@p9 datetime2(7),
@p10 uniqueidentifier,
@p11 uniqueidentifier,
@p12 datetime2(7),
@p13 uniqueidentifier,
@p14 datetime2(7),
@p15 uniqueidentifier,
@p16 uniqueidentifier,
@p17 datetime2(7),
@p18 uniqueidentifier,
@p19 datetime2(7),
@p20 uniqueidentifier,
@p21 uniqueidentifier,
@p22 datetime2(7),
@p23 uniqueidentifier,
@p24 datetime2(7)',
@p5='015B76FC-2833-45D9-85A7-AB1C389C1C11',
@p6=NULL,
@p7='2018-11-10 14:29:25.5363017',
@p8='35C38DF0-A959-4232-AADD-40DB2260F557',
@p9='2018-11-10 14:29:25.5363022',
@p10='538EE0DD-531A-41C6-8414-0769EC5990D8',
@p11=NULL,
@p12='2018-11-10 14:29:25.5363031',
@p13='35C38DF0-A959-4232-AADD-40DB2260F557',
@p14='2018-11-10 14:29:25.5363034',
@p15='8288D9AC-FBCE-417E-89EF-82266B284B78',
@p16=NULL,
@p17='2018-11-10 14:29:25.5363039',
@p18='35C38DF0-A959-4232-AADD-40DB2260F557',
@p19='2018-11-10 14:29:25.5363042',
@p20='4BCFE9F8-E4A5-49F0-B6EE-44871632A903',
@p21='35C38DF0-A959-4232-AADD-40DB2260F557',
@p22='2018-11-10 14:29:25.5363047',
@p23='35C38DF0-A959-4232-AADD-40DB2260F557',
@p24='2018-11-10 14:29:25.5363047'
I suspect that this issue has its roots in the "IsUnique(false")
line of code I highlighted in the second snippet as this only happens for the AddedByAccountId
property/column. However, if I don't include this line then the migration script created will add on a unique constraint (which I don't want).
Has anyone encountered issues with either constraints being created when they shouldn't or (more importantly) NULL values replacing actual data on insert?
Cheers.
// For some reason this self referencing key generates a unique
// constraint in the migration script if we don't set this here.// "ModifiedByAccountId" does not have this issue! I suspect this might
// the root cause of the NULL data issue.
You suspect it right. EF Core is confused from the 2 self referencing navigation properties and wrongly decides (could be a bug) that they represent a single One-to-one relationship:
One to one relationships have a reference navigation property on both sides. They follow the same conventions as one-to-many relationships, but a unique index is introduced on the foreign key property to ensure only one dependent is related to each principal.
Of course what you want is two one-to-many relationships, so rather than fixing the index (which won't help as you already saw), just map them explicitly:
modelBuilder.Entity<Account>().HasOne(e => e.AddedByAccount).WithMany();
modelBuilder.Entity<Account>().HasOne(e => e.ModifiedByAccount).WithMany();