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Updated Documentation to Reflect Changes in #11696 (#12877)

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Liam Cottrell 2019-06-14 12:39:50 +01:00 committed by Luke Latham
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aspnetcore/data/ef-mvc/concurrency.md
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@ -149,7 +149,7 @@ Replace the existing code for the HttpPost `Edit` method with the following code
[!code-csharp[](intro/samples/cu/Controllers/DepartmentsController.cs?name=snippet_EditPost)]
The code begins by trying to read the department to be updated. If the `SingleOrDefaultAsync` method returns null, the department was deleted by another user. In that case the code uses the posted form values to create a department entity so that the Edit page can be redisplayed with an error message. As an alternative, you wouldn't have to re-create the department entity if you display only an error message without redisplaying the department fields.
The code begins by trying to read the department to be updated. If the `FirstOrDefaultAsync` method returns null, the department was deleted by another user. In that case the code uses the posted form values to create a department entity so that the Edit page can be redisplayed with an error message. As an alternative, you wouldn't have to re-create the department entity if you display only an error message without redisplaying the department fields.
The view stores the original `RowVersion` value in a hidden field, and this method receives that value in the `rowVersion` parameter. Before you call `SaveChanges`, you have to put that original `RowVersion` property value in the `OriginalValues` collection for the entity.