Data Binding. Data Binding

Transcription

1 Data Binding Data Binding How to Populate Form Controls? Specify the data in the control s properties Not dynamic: can t get data from a database Write code that uses the control s object model This is okay if you need to populate a simple value or list, but quickly gets too complicated for populating sophisticated displays Data binding Create an object that holds the data (DataSet, Array, string, int, etc.) Associate that object with the control

2 Data Binding What Is It? Provides a single simple yet powerful way to populate Web controls with data Enables clean separation of code from UI Supports binding to any data source Properties, expressions, method calls Collections (Array, Hashtable, etc.) DataSet, DataTable, DataView, DataReader XML Data Sources Window Drag and drop operations Dragging/dropping tables from Data Sources Window onto form will create instances of: DataSet, TableAdapter, BindingSource BindingNavigator with nav/add/delete/save controls Bound control(s) Use Data Sources window to configure: Whether table will be edited with DataGridView or Details mode (individual controls) Mapping of detail control types to column data types (shortcut to Windows Forms Designer/Data UI Customization node in Options dialog)

3 Data Source Options Database (DataSet) Any ADO.NET data source Web Service Bind to parameterized methods of a Web service, for select, update, delete, and insert operations Object Bind to instances of classes and their properties (more later!) WinForms 2.0 Data Binding Introduction to Objects Typed DataSet DataTable, TableAdapter BindingSource [BindingNavigator]

4 Strongly-Typed DataSets As before Consist of DataTables, Relations, Constraints Drag/drop from Server Explorer is supported Based on XML schema and code-behind class Also consists of TableAdapters Encapsulate a DataAdapter and a Connection Enhanced Typed Dataset Designer Instead of XSD Designer earlier Partial class support TableAdapters Have Queries (methods for handling selects, updates, inserts, deletes) Queries exists as methods Fully customizable and extendable Can be re-used across multiple forms Have Connection property Connection string typically stored in web/app.config; default value applied in WinForms apps.

5 BindingSource: Basics Acts as broker between bound controls and actual data source DataSource, DataMember Point to typed DataSet, DataTable AllowEdit, AllowNew, AllowRemove Filter, Sort properties Run time: RemoveFilter, RemoveSort methods BindingSource Run time members MovePrevious, MoveNext, MoveFirst, MoveLast, Position, Count properties (handles all navigation) AddNew, Insert(index, obj) methods RemoveCurrent, RemoveAt(index), Remove(obj) EndEdit, CancelEdit methods Works with edits and inserts/new s Use of most of these is optional due to

6 BindingNavigator UI provider that wraps navigation and maintenance functionality of BindingSource Not like old VB data control Has UI component Specialized toolstrip Has tray component too Selecting one will select both Members that associate ToolStrip controls with specific actors DeleteItem = bindingnavigatordeleteitem (ToolStripButton) How It All Connects DataSource Complex Control DataSet DataTable DataMember DataSource Column BindingSource BindingSource Property DataBinding BindingNavigator Simple Control Changes control contents via navigation, maintenance

7 Complex and Simple Binding Scenarios Complex Binding DataGridView.DataSource = BindingSource SimpleBinding TextBox.Text (and other controls/string-based properties) bound to member of BindingSource BindingNavigator.BindingSource = BindingSource