The series continues here in part 2. Reverse engineering is the process of scaffolding entity type classes and a DbContext class based on a database schema. In a project select add new item, data, ADO. Once installed right click on a project to create the complete structure. Scaffolding can also be done through the power shell interface in Visual Studio which take a good deal of knowledge to get it right.
There are four tables from a SQL-Server database used to present customer data in a DataGridView, a customer table, a contact table, a contact type and a country table where the parent table, customer contains primary keys for each of the child tables. The DbContext class more tables than necessary for this article for future lessons. There are also several custom methods which provide access to the ChangeTracker to determine changes to the data. The method name is GetPrimaryKeyValue.
Implementing INotifyPropertyChanged Interface is considered the glue to allowing form controls such as a DataGridView to know when a underlying value has changed which coupled with the sortable BindingList see below allows immediate updates to be done using ListChanged event of the BindingList.
Each property to be displayed in the DataGridView were created at design time to specify the column type and DataPropertyName which indicates the property within the customer list to display. Meanwhile, you need to write "plumbing" code yourself to handle them.
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An ORM also helps to keep track of changes to those objects, and when instructed, it will also persist those changes back to the database for you. Entity Framework can generate the necessary database commands for reading or writing data in the database and execute them for you. If you're querying, you can express your queries against your domain objects using LINQ to entities. Entity Framework will execute the relevant query in the database and then materialize results into instances of your domain objects for you to work within your app.
Most ORMs typically map domain types directly to the database schema. Entity Framework has a more granular mapping layer so you can customize mappings, for example, by mapping the single entity to multiple database tables or even multiple entities to a single table. Entity Framework is where all of the forward moving investment is being made, which has been the case for a number of years already.
For developers who are used to database focused development, the biggest shift with Entity Framework is that it lets you focus on your business domain. What it is that you want your application to do without being limited by what the database is able to do? With Entity Framework, the focal point is referred to as a conceptual model.
It's a model of the objects in your application, not a model of the database you use to persist your application data. Your conceptual model may happen to align with your database schema or it may be quite different. You can use a Visual Designer to define your conceptual model, which can then generate the classes you will ultimately use in your application.
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