c# ef6 sqlite rowversion

In EF6, you can use the [Timestamp] attribute to mark a property as a row version in SQLite.

Here's an example of how you can define a row version property in a class using EF6 and SQLite:

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

public class YourEntity
{
    [Key]
    public int Id { get; set; }

    // Row version property
    [Timestamp]
    [Column(TypeName = "rowversion")] // Use "rowversion" in SQLite
    public byte[] RowVersion { get; set; }

    // Other properties
    public string Name { get; set; }
    public string Description { get; set; }
}

In the above code, the RowVersion property is marked with the [Timestamp] attribute, which indicates that it should be treated as a row version. Additionally, the [Column(TypeName = "rowversion")] attribute is used to specify the column type as "rowversion" in SQLite.

When you update an entity instance, EF6 will automatically check the row version value in the database against the value in the entity. If they don't match, it will throw a DbUpdateConcurrencyException, indicating that a concurrent update occurred.

Here's an example of how you can use the row version property to handle concurrency conflicts:

using (var context = new YourDbContext())
{
    var entity = context.YourEntities.Find(id);

    // Make some changes to the entity
    entity.Name = "New Name";

    try
    {
        context.SaveChanges();
    }
    catch (DbUpdateConcurrencyException ex)
    {
        // Handle concurrency conflict
        var entry = ex.Entries.Single();
        var databaseValues = entry.GetDatabaseValues();

        // Update the entity with the latest values from the database
        if (databaseValues != null)
        {
            var databaseEntity = (YourEntity)databaseValues.ToObject();
            entry.OriginalValues.SetValues(databaseEntity);
        }
        else
        {
            // Handle case where the entity was deleted in the database
            entry.State = EntityState.Deleted;
        }

        // Retry the save operation
        context.SaveChanges();
    }
}

In the above code, if a concurrency conflict occurs during the SaveChanges() operation, a DbUpdateConcurrencyException is thrown. The code then retrieves the latest values from the database and updates the entity with those values before retrying the save operation.

Note that the row version property should be of type byte[] in EF6 to store the row version value.