DataSource for Entity Framework in WPF > Simple Binding |
We’ll begin by creating a new Windows Forms project in Visual Studio.
Note: When you install DataSource for Entity Framework, ComponentOne EF6.x DBContext Code Generation Templates will be added to each version of Visual Studio that C1DataSource supports. These templates ensure that the DBContext models that you create, provide entities that support INotifyPropertyChanged.
At this point, the C1DataSource has created an application-wide object (an EntityDataCache) that represents the Northwind database and has application scope. Additional C1DataSource objects on other forms will share that same object. As long as they are part of the same application, all C1DataSource objects share the same ObjectContext.
This unified object context is one of the main advantages C1DataSource provides. Without it, you would have to create multiple object contexts throughout the application, and each would have to be synchronized with the others and with the underlying database separately. This would be a non-trivial task, and any errors could compromise the integrity of the data. The unified object context handles that for you transparently. It efficiently caches data and makes it available to all views in a safe, consistent way.
Now that our C1DataSource has an ObjectContext to work with, we will go on to specify the entity sets it will expose to the application through its ViewSources collection. Note that if you are familiar with ADO.NET, you can think of the C1DataSource as a DataSet and the ViewSources collection as DataView objects.
For this simple example, Products is all that is really necessary, but we could continue to create ViewSources within this C1DataSource in exactly the same way. We might, for example, create a ViewSource based on the Categories entity set allowing us to have a form that would be used to show the master-detail relationship between Categories and their Products. Conversely, there is no need to define all of the ViewSources that you might need in one single C1DataSource. You could have a separate C1DataSource for each ViewSource that you need. All you need to do is ensure that the C1DataSource components that you use utilize the same ContextType.
In reality we’ll only want to bring a small subsection of the data contained within our database back to the client at any one time. This avoids overloading the client and network and also ensures that we are only presenting data that is relevant to the task our end user is engaged in. The traditional approach to this has been to create code (typically SQL queries) that we would run against the database to achieve our desired results. With C1DataSource, we can make use of the designer surface to achieve our goal without the need to write code by specifying server-side filters as property settings.
Using exactly the same methodology, you can add SortDescriptors and GroupDescriptors to provide sorting and grouping on the data you retrieve.
With our C1DataSource configured, add a grid control to the form. This can be DataGridView, a C1FlexGrid or indeed any grid that you are familiar with. Set the grid’s DataSource property to the name of the C1DataSource (if you haven’t specifically named the C1DataSource, then this will be c1DataSource1) and its DataMember property to Products. The DataMember property will, in fact, display a drop-down list of all the ViewSources (or Entity Sets) that we defined for the C1DataSource.
At this point, the grid will automatically generate columns for all the fields in the Product type, and most grids will allow you to further customize these columns and their layout via their built-in designers.
You could continue to add more controls to this form and bind them to specific items in the Products collection. To illustrate this point, add a TextBox control to the form. From the Properties window, expand the DataBindings section and bind its Text property to the ProductName, as illustrated.
Save, build and run the application again, and this time notice how the name of the product currently selected in the grid appears in the TextBox that you have just added to the form. If you then edit the product name in either control, the change will be immediately reflected in the other.