Getting all changes made to an object in the Entity Framework

Question

Getting all changes made to an object in the Entity Framework

c# entity-framework

Question

Is there a way to get all the changes made to a object in the Entity Framework before it saves all changes. The reason for this is that i want to create a log table in our clients database:

so...

Is there a way to get the current database values(old) and the new values(current) before changes are saved?

If not, how can i achieve this in a generic way, so all my View Models can inherit from this?(I am using the MVVM + M Structure)

Willem

Popular Answer

For EF5 upwards you can log your changes in the SaveChanges() method like this:

    public override int SaveChanges()
    {

        var changes = from e in this.ChangeTracker.Entries()
                      where e.State != System.Data.EntityState.Unchanged
                      select e;

        foreach (var change in changes)
        {
            if (change.State == System.Data.EntityState.Added)
            {
                // Log Added
            }
            else if (change.State == System.Data.EntityState.Modified)
            {
                // Log Modified
                var item = change.Cast<IEntity>().Entity;
                var originalValues = this.Entry(item).OriginalValues;
                var currentValues = this.Entry(item).CurrentValues;

                foreach (string propertyName in originalValues.PropertyNames)
                {
                    var original = originalValues[propertyName];
                    var current = currentValues[propertyName];

                    if (!Equals(original, current))
                    {
                        // log propertyName: original --> current
                    }
                }

            }
            else if (change.State ==  System.Data.EntityState.Deleted)
            {
                // log deleted
            }
        }
        // don't forget to save
        base.SaveChanges();
    }

JÃ¼rgen Steinblock

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Panagiotis Kanavos · Accepted Answer · 10/25/2016 1:19:57 AM

You can use ObjectContext's ObjectStateManager,GetObjectStateEntry to get an object's ObjectStateEntry, which holds its original and current values in the OriginalValues and CurrentValues properties. You can get the names of the properties that changed using the GetModifiedProperties method.

You can write something like:

var myObjectState=myContext.ObjectStateManager.GetObjectStateEntry(myObject);
var modifiedProperties=myObjectState.GetModifiedProperties();
foreach(var propName in modifiedProperties)
{
    Console.WriteLine("Property {0} changed from {1} to {2}", 
         propName,
         myObjectState.OriginalValues[propName],
         myObjectState.CurrentValues[propName]);
}

Getting all changes made to an object in the Entity Framework

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