Assuming we had a few posts tagged with 'entity-framework' and 'asp. One final thing to note about Local is that because it is an ObservableCollection performance is not great for large numbers of entities. Therefore if you are dealing with thousands of entities in your context it may not be advisable to use Local.
As described in the previous sections this means that it will automatically stay in sync with the contents of the context and the contents of the context will automatically stay in sync with it.
Note that you do need to pre-populate the Local collection with data for there to be anything to bind to since Local never causes a database query. An easy way to make this work is to use an ObservableCollection for the navigation property. In most cases entities removed from a navigation property will not be automatically marked as deleted in the context.
For example, if you remove a Post object from the Blog. Posts collection then that post will not be automatically deleted when SaveChanges is called. If you need it to be deleted then you may need to find these dangling entities and mark them as deleted before calling SaveChanges or as part of an overridden SaveChanges. The code above uses the Local collection to find all posts and marks any that do not have a blog reference as deleted.
The ToList call is required because otherwise the collection will be modified by the Remove call while it is being enumerated. In most other situations you can query directly against the Local property without using ToList first. Windows Forms does not support full fidelity data binding using ObservableCollection directly. However, you can still use the DbSet Local property for data binding to get all the benefits described in the previous sections.
This is not an appropriate place for a full Windows Forms data binding sample but the key elements are:. Many of the examples in this series use the Entry method to return a DbEntityEntry instance for an entity. SqlClient' ADO. NET provider could not be loaded. Make sure the provider assembly is available to the running application.
I have double checked my references and I have EntityFramework. SqlServer and System. Data both added into my project. The connection string I use to connect to the data base and declare the service provide is below.
I am pretty new to this entire thing and was just handed someone elses code so I am trying to learn on the flow. This is my first encounter with this so any direction would be appreciated. I had the same problem in my integration test assembly i'm using ms visual studio unit testing framework for this and i've solved it by adding EF assemblies to deployment items in.
SqlServer assembly there SqlProviderServices class resides in it. So i've just added both EF 6 assemblies to my deployment items and now everything is ok. You can try to copy EntityFramework. SqlServer assembly to your web server directory to see if it works. This video and step-by-step walkthrough provide an introduction to Database First development using Entity Framework.
Database First allows you to reverse engineer a model from an existing database. The model is stored in an EDMX file. The classes that you interact with in your application are automatically generated from the EDMX file. This video provides an introduction to Database First development using Entity Framework. Presented By : Rowan Miller.
You will need to have at least Visual Studio or Visual Studio installed to complete this walkthrough. If you are using Visual Studio , you will also need to have NuGet installed. Typically when you are targeting an existing database it will already be created, but for this walkthrough we need to create a database to access. The database server that is installed with Visual Studio is different depending on the version of Visual Studio you have installed:. Blogging as the database name.
Select OK and you will be asked if you want to create a new database, select Yes. The new database will now appear in Server Explorer, right-click on it and select New Query. Copy the following SQL into the new query, then right-click on the query and select Execute.
Select Data from the left menu and then ADO. Select the connection to the database you created in the first section, enter BloggingContext as the name of the connection string and click Next.
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