The IsConcurrencyToken method is used to specify that a property should be included in a WHERE clause in an UPDATE or DELETE statement as part of concurrency management.
language-csharp
|
public class SampleContext : DbContext
{
public DbSet<Author> Authors { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Author>()
.Property(a => a.FirstName).IsConcurrencyToken()
modelBuilder.Entity<Author>()
.Property(a => a.LastName).IsConcurrencyToken();
}
}
public class Author
{
public int AuthorId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Biography { get; set; }
public ICollection<Book> Books { get; set; }
}
When applied to a byte array property in combination with the ValueGeneratedOnAddOrUpdate method, the IsConcurrencyToken method denotes that the property should map to a database type that provides automatic row-versioning, such as the SQL Server rowversion type:
language-csharp
|
public class SampleContext : DbContext
{
public DbSet<Author> Authors { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Author>()
.Property(a => a.RowVersion)
.IsConcurrencyToken()
.ValueGeneratedOnAddOrUpdate();
}
}
public class Author
{
public int AuthorId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Biography { get; set; }
public ICollection<Book> Books { get; set; }
public byte[] RowVersion { get; set; }
}
Data Annotations
The Data Annotations equivalents are the IsConcurrencyToken method is the ConcurrencyCheck attribute and the Timestamp attribute.
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