Get the Entity Name when calling SaveChanges in Entity Framework 6.1.3

asp.net-mvc c# entity-framework entity-framework-6

Question

I am trying to override the SaveChanges() method in my DbContext class, this because I try to get the name of the entity with a row added, deleted or updated an the respective ID of the row and the action performed.

I don't know how to do this.

This is with logs actions purposes.

Greetings in advance.

1
2
6/7/2017 4:40:07 AM

Accepted Answer

You need to override SaveChanges method of DbContext and use ChangeTracker to track the changes made to entities before it gets saved to database.public

public class ChangeLog  
{
    public string EntityName { get; set; }
    public string PropertyName { get; set; }
    public string OldValue { get; set; }
    public string NewValue { get; set; }
}

public override int SaveChanges()  
{
    var modifiedEntities = ChangeTracker.Entries()
        .Where(p => p.State == EntityState.Modified).ToList();

    foreach (var change in modifiedEntities)
    {
        var entityName = change.Entity.GetType().Name;

        foreach(var prop in change.OriginalValues.PropertyNames)
        {
            var originalValue = change.OriginalValues[prop].ToString();
            var currentValue = change.CurrentValues[prop].ToString();
            if (originalValue != currentValue)
            {
                ChangeLog log = new ChangeLog()
                {
                    EntityName = entityName,
                    PropertyName = prop,
                    OldValue = originalValue,
                    NewValue = currentValue,
                };
                ChangeLogs.Add(log);
            }
        }
    }        
    return base.SaveChanges();
}

In above snippet we have queried change tracker api to fetch the entities that are modified

var modifiedEntities = ChangeTracker.Entries()
        .Where(p => p.State == EntityState.Modified).ToList();

Same way you can query entities that are added and deleted.

Edit

object GetPrimaryKeyValue(DbEntityEntry entry)  
{
        var stateEntry = ((IObjectContextAdapter)this).ObjectContext.ObjectStateManager.GetObjectStateEntry(entry.Entity);
        return stateEntry.EntityKey.EntityKeyValues[0].Value;
}

Note: If you have Identity Insert set to On then for added entity above snippet will not work.

4
6/8/2017 6:35:16 AM


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