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2010-10-01T20:02:34.087
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I think you misunderstood MergeOption.OverwriteChanges. By default, anytime the ObjectContext performs a query, if any of the returned objects already exist in the cache the newly returned copies of those objects are ignored. Please note that it all happens based on the EntityKeys. Basically the EntityKeys of the objects returned from a query are checked, and if an object with the same EntityKey (in the same EntitySet, in your case, Lectures) already exists in the cache, the existing object is left untouched. However, if you enable <a href="http://msdn.microsoft.com/en-us/library/system.data.objects.mergeoption.aspx" rel="noreferrer">OverwriteChanges</a>, then it will Replace the current values of existing entities with values coming from the database, even if the in-memory entity has been edited. As you can see you are adding a Lecture to the student that is totally new to Student and it will not be overwritten since its EntityKey is different than the ones that coming from database as per your LoadProperty() call. One solution would be to just simply clear all the Lectures from your student object just before LoadProperty(): <pre><code>public void CancelChanges() { _context.Refresh(RefreshMode.StoreWins, this); this.Lectures.Clear(); _context.LoadProperty(this, (o) => o.Lectures, MergeOption.OverwriteChanges); } </code></pre>
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1. POEntity Framework POCO - Refresh a navigation property
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1. USMorteza Manavi
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1. COThanks a lot for the explanation - it has made a lot of things a lot clearer in my head. And the solution you proposed is very handy - I just updated my code and the thing actually works.
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2. COYou are very welcome, I'm glad it helped :)
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Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.