Perform action when an entity is updated in Entity Framework-CodePudding

Is there a way to run code when an entity is updated? For example I have an entity that is updated many places in my code. I want to be able to update a DateTimeUpdated field any time that entity is updated without changing every function that updates that entity.

CodePudding user response：

This is typically done by overriding the SaveChanges method in the DbContext.

Start by introducing a base class or a common interface for your editable entities that you want to track the DateTimeUpdated for:

public abstract class EditableEntityBase
{
    public DateTime DateTimeUpdated { get; internal set; } 
}

Your entities that you want to track this for should extend this class or implement a contract interface that will expose the property.

Then in your DbContext, override the SaveChanges method and insert:

var updatedEntities = ChangeTracker.Entries()
    .Where(x => x.State == EntityState.Modified)
    .Select(x => x.Entity)
    .OfType<EditableEntityBase>();
foreach (var entity in updatedEntities)
{
    entity.DateTimeUpdated = DateTime.Now; // or DateTime.UtcNow
}

return base.SaveChanges();

You can also include x.State == EntityState.Added for new records, though generally I'd rely on a Default at the DB to capture it on insert.