EntityFramework get changed/modified properties after SaveChanges()

Question

I have a very simple web api method that looks like this:

    public void Put(Vehicle vehicle)
    {
        db.Entry(vehicle).State = EntityState.Modified;
        db.SaveChanges();
    }

All it does is updating the direct properties of the vehicle entity. This works fine like this. But I would now like to know which properties have actually changed? Is there a way to do this?

I probably could get the vehicle from the database first and then compare it to the modified vehicle. But maybe there is an easier way.

Thanks

You can even look into the change tracker to see what entities are set to, and do further things based on that like auditing... — Callum Linington
– Callum Linington, Commented Jul 7, 2015 at 15:00
context.ChangeTracker.Entries<ITrackedEntity>().Where(entry => entry.State == EntityState.Added) — Callum Linington
– Callum Linington, Commented Jul 7, 2015 at 15:03
as far as I can see this requires to get the vehicle from the db first: entityframeworktutorial.net/… — Timothy
– Timothy, Commented Jul 8, 2015 at 13:20
The change tracker is in memory so why would you go to the db, just read that tutorial and it doesnt say that at all..... — Callum Linington
– Callum Linington, Commented Jul 8, 2015 at 14:30

Disappointed · Accepted Answer · 2015-07-07 14:30:13Z

1

Look at this

DbContext.Entry(vehicle).OriginalValues

And compare these values with your input vehicle

answered Jul 7, 2015 at 14:30

Disappointed

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2 Comments

Timothy Over a year ago

this doesn't seem to work, Original and CurrentValues are the same

bubi Over a year ago

They are the same after serialization on database.

Timothy · Accepted Answer · 2015-07-07 14:48:14Z

0

db.Entry(vehicle).GetDatabaseValues()

I found this and it seems to work. Now I just need to compare them

answered Jul 7, 2015 at 14:48

Timothy

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2 Comments

bubi Over a year ago

"I probably could get the vehicle from the database first and then compare it to the modified vehicle. But maybe there is an easier way." :)

Timothy Over a year ago

yes but on a second thought it's probably impossible to do it without getting the vehicle from the db. EF will just write an update query with all the fields that are not PK. So from that update query there is no chance to know what has changed...

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