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C#: How to refresh Entity Framwork 6 entity list?

Posted on 2016-09-25
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Last Modified: 2016-09-29
I've got a class library that includes a static Account entity (it's called by an external program so almost everything has to be static). Account has a list of Alert entities among other things. I've now added a website where I can add, update and delete Alerts for each account to the database, but I'm struggling with figuring out how the class library should reload the Alerts on a timer.

Basically what I want to do is something like myaccount.Alerts.Reload(), but there is no Reload (or Refresh) function in EF 6.

Any suggestions?
TIA!
Dennis
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Question by:Dennis_Gundersen
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8 Comments
 
LVL 70

Expert Comment

by:Éric Moreau
ID: 41815937
You can call the Refresh method of your object context as shown in https://msdn.microsoft.com/en-us/library/bb896255(v=vs.110).aspx:

YourObjectContext.Refresh(RefreshMode.StoreWins, YourEntity);

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Author Comment

by:Dennis_Gundersen
ID: 41815942
Unfortunately, that function is gone in EF 6. db.Refresh(...), simply doesn't show up in my project. It must have been supplanted by something else, but I can't find it anywhere.

Re
Dennis
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LVL 70

Expert Comment

by:Éric Moreau
ID: 41815948
what is db? Surely not an ObjectContext!
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Author Comment

by:Dennis_Gundersen
ID: 41815952
Yes, "db" is my static variable for the DbContext. I believe the ObjectContext has been replaced some time ago.

Re
D
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LVL 70

Accepted Solution

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Éric Moreau earned 2000 total points
ID: 41815956
A DbContext is not an ObjectContext! Convert it like this:
var context = new YourDbContext();
var adapter = (IObjectContextAdapter)context;
var objectContext = adapter.ObjectContext;

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Author Comment

by:Dennis_Gundersen
ID: 41815976
OK, that's smart, but I still see one problem. I don't want to update the complete Account entity, since that would entail loading potentially millions on rows of Result and Order entities for that Account as well. I just want to reload myaccount.Alerts (which would probably be 5-6 rows only).
I'm thinking it may be possible with something like this:

            using (var context = new HGContext())
            {
                var adapter = (IObjectContextAdapter)context;
                var objectContext = adapter.ObjectContext;
                objectContext.Refresh(System.Data.Entity.Core.Objects.RefreshMode.StoreWins, acc.Alerts);
            }

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I'm then assuming that this would take my static Account entity and only refresh it's Alerts collection. Am I understanding this correctly?

Re
D
0
 
LVL 70

Expert Comment

by:Éric Moreau
ID: 41815990
I have situations where I refresh only one entity (table). What you wrote (acc.Alerts) should work. If you want to be sure of what is getting refreshed, open the SQL Profiler to see the query.
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Author Comment

by:Dennis_Gundersen
ID: 41815995
Alright then, this sounds very promising. It's going to take me a while to actually test this out completely, but I'm hopeful and will just add another question of something should fail with the finer details.
Thank you very, very much!
Re
Dennis
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