Entity Framework - refresh objects from database

Question

I\'m having trouble with refreshing objects in my database. I have an two PC\'s and two applications.

On the first PC, there\'s an application which communicates with my

Answer 1

Another possibility is to use MergeOption to decide how you want to manage the objects in the context. For example MergeOption.OverwriteChanges will overwrite the object context with values from the data source.

For more info see http://msdn.microsoft.com/en-us/library/system.data.objects.mergeoption.aspx

Answer 2

As of EF 4.1 you can use AsNoTracking() method on your entities.

return myEntities.Measurements.AsNoTracking();

Note that AsNoTracking() will not add the entities to your context for tracking, but merely return them fresh from your data store.

For more info see http://blogs.msdn.com/b/adonet/archive/2011/02/05/using-dbcontext-in-ef-feature-ctp5-part-11-load-and-asnotracking.aspx

Answer 3

This should work:

public static Entities myEntities = new Entities();

public static Measurement GetLastMeasurement(int conditionId)
{
    myEntities.Refresh(RefreshMode.StoreWins, myEntities.Measurements);
    var allMeasurements = myEntities.Measurements.ToList();//retrieves all measurements from database

    return (from measurement in allMeasurements
            where measurement.ConditionId == conditionId
            select measurement).OrderByDescending(cd => cd.Timestamp).First();
}

What sense makes caching when you refresh store every time you want to use it? You could chage it to:

public Measurement GetLastMeasurement(int conditionId)
{
    var entities = new Entities();
    return (from measurement in entities.Measurements
            where measurement.ConditionId == conditionId
            select measurement).OrderByDescending(cd => cd.Timestamp).First();
}

It also look up in database with every call, but makes much less operations.