Download asp:ObjectDataSource ID

Data Access in ASP.NET 2.0
Bradley Millington
Program Manager
Web Platform and Tools
Agenda
• Visual Web Developer 2005 & SQL Server 2005
– All you need to build rich data-driven apps!
– Free Express Editions of both products
• ASP.NET Data Controls
– Enable declarative data binding in ASP.NET 2.0
• Scenarios Covered
–
–
–
–
–
–
–
Creating and connecting to a database in VS
Selecting and displaying data in a web page
Sorting, paging, updating, deleting, inserting data
Caching, filtering, master-details, parameters
Binding to business objects (DAL, BLL)
Data binding in custom templated UI
Hierarchical data (XML, SiteMap)
ASP.NET 2.0 and Data Controls
• Data access/presentation too hard in ASP.NET V1
– No declarative model for data acquisition/manipulation
– Common scenarios required 100s of lines of code
• 2.0 provides easy and powerful declarative model
– Handle stateless Web model for data scenarios
– Do not require developer to be aware of page lifecycle events
– Enable rich and pluggable data access storage providers
• Common UI scenarios with little to zero code
–
–
–
–
Selecting and displaying data
Sorting, paging, caching data
Updating, inserting, deleting data
Filtering, master-details (parameterization)
ASP.NET 2.0 and Data Controls
• Data Source Controls
– Non-UI controls (no rendering)
– Represent different backend data sources
• Databases, Business Objects, XML, or Web Services
– Can cache, sort, page, filter, update, delete, insert data
– Expose data through tabular or hierarchical interfaces
• Data-bound Controls
– UI controls to render data
• GridView, DetailsView, FormView, TreeView, Menu
– Auto-bind to data exposed from a data source
– Fetches data at the appropriate time in lifecycle
– Can take advantage of data source capabilities
Data Control Types
Data-bound Control
<asp:GridView
<asp:TreeView
DataSourceId=“MySource”
runat=“server”/>
runat=“server”> …
Data Source Control
<asp:XmlDataSource
<asp:ObjectDataSource
<asp:SqlDataSource
Id=“MySource”
DataFile=“Bookstore.xml”
TypeName=“CustomersDB”
ConnectionString=“…”
XPath=“/bookstore/book[@genre=‘fiction’]”
SelectMethod=“GetCustomersByRegion”
SelectCommand=“select id from authors”
runat=“server” />
Database
Business
Object
XML
Document
demo
Binding to Databases with
SqlDataSource
Bradley Millington
Program Manager
Web Platform and Tools
Binding to Objects
• Most applications encapsulate data logic from
presentation layer as a best practice
– Embedding SQL code in a page is not ideal
• ObjectDataSource enables declarative binding to
middle-tier objects
– Select, update, insert, delete, filter and cache data
– Supports custom paging and sorting
<asp:ObjectDataSource
Id=“MySource”
TypeName=“CustomersDB”
SelectMethod=“GetCustomers”
UpdateMethod=“UpdateCustomer”
DeleteMethod=“DeleteCustomer”
InsertMethod=“InsertCustomer”
runat=“server” />
Binding to Objects
• Select method can return any Object
or IEnumerable list, collection, or array
• GetProducts() -> ProductCollection
• GetProductsDataSet() -> DataSet
• GetProduct (int productId) -> Product
• Update, Insert, Delete methods
take individual fields or data item object
• UpdateProduct (int id, String name, double price, bool inStock)
• UpdateProduct (Product p) // p.Name, p.Price, p.InStock …
• DeleteProduct (int id)
• Property or parameter names must match selected fields
for GridView/DetailsView automatic
updates/deletes/inserts
Binding to Objects
Web Page
<asp:ObjectDataSource
ID = ObjectDataSource1
TypeName = OrdersComponent
SelectMethod = GetOrders
UpdateMethod = UpdateOrder
DeleteMethod = DeleteOrder
DataSourceID = ObjectDataSource1
Returns IEnumerable of Orders
• Order.OrderID
• Order.OrderName
• Order.OrderDate
OrderItemsComponent
OrdersComponent
CompaniesComponent
Northwind
Database
demo
Binding to Objects with
ObjectDataSource
Bradley Millington
Program Manager
Web Platform and Tools
Data Source Paging
• Previous example does paging in UI layer
– ObjectDataSource returns all data rows
– GridView performs paging by rendering subset of rows
• Paging also supported on data source interface
– Select (int startRowIndex, int maxRows)
– Can be implemented in user-defined stored proc or custom
method
• Data-bound controls (e.g., GridView) can use data
source paging, if supported by data source
– Don’t need to page in the UI layer
– Useful (required) for large amounts of data
Programmability And Events
• Creating, Created
– Raised before/after object instantiated
– Can assign to ObjectInstance
• Selecting, Filtering, Updating, Deleting, Inserting
– Raised before operation
– Can optionally cancel event
– Can validate and manipulate parameters
• Selected, Updated, Inserted, Deleted
– Raised after operation complete
– Can check and handle exceptions
– Can obtain return values and out params
• Disposing
– Raised prior to releasing object
– Dispose() will be called if object implements IDisposable
– Can optionally cancel
Data Source Events
Page.aspx.vb
Sub MySource_Selecting(ByVal sender As Object,
ByVal e As SqlDataSourceCommandEventArgs)
Dim cmd As System.Data.SqlClient.SqlCommand = e.Command
cmd.Parameters(“UserId”).Value = User.Identity.Name
End Sub
Page.aspx
<asp:SqlDataSource ID=“MySource” …
OnSelecting=“MySource_Selecting”
SelectCommand=“sp_GetUserPreferences”
runat=“server”/>
Filtering and Master-Details
• Select Method or Command may be parameterized
• GetCustomersByCountry (int countryCode) -> CustomersCollection
• GetOrdersForCustomer (String customerId) -> OrdersCollection
• GetProduct (int productId) -> Product
• Data source parameter collections enable declarative
associations to values
–
–
–
–
–
–
–
QueryStringParameter
ControlParameter
SessionParameter
FormParameter
CookieParameter
ProfileParameter
Static Parameter
Filtering Data
Orders.aspx?company=Microsoft
OrdersComponent
Web Page
<asp:ObjectDataSource ID = ObjectDataSource1
TypeName = OrdersComponent
OrderItemsComponent
SelectMethod = GetOrdersBy
<SelectParameters>
CompaniesComponent
<asp:QueryStringParameter
Name=“companyName”
Northwind
QueryStringField=“company”/>
Database
</SelectParameters>
Filtering Data
Web Page
<asp:ObjectDataSource
ID = ObjectDataSource2
TypeName = CompaniesComponent
SelectMethod = GetCompanies
OrdersComponent
Developer API
<asp:ObjectDataSource ID = Page
ObjectDataSource1
TypeName = OrdersComponent
OrderItemsComponent
SelectMethod = GetOrdersBy
<SelectParameters>
CompaniesComponent
<asp:ControlParameter
Name= companyName
Northwind
ControlID= DropDownList1 />
Database
</SelectParameters>
Master-Details (1 Page)
Web Page
<asp:GridView ID = GridView1
AutoGenerateSelectButton = true
OrdersComponent
<asp:ObjectDataSource ID = ObjectDataSource2
TypeName = OrdersComponent
OrderItemsComponent
SelectMethod = GetOrderBy
<SelectParameters>
<asp:ControlParameter
CompaniesComponent
Name= orderID
Northwind
ControlID= GridView1 />
Database
</SelectParameters>
Master-Details (2 Page)
Master Page
Details Page
<asp:GridView ID = GridView1
<ColumnFields>
<asp:HyperLinkField … />
</ColumnFields>
OrdersComponent
<asp:ObjectDataSource ID = ObjectDataSource2
TypeName = OrdersComponent
OrderItemsComponent
SelectMethod = GetOrderBy
<SelectParameters>
<asp:QueryStringParameter
CompaniesComponent
Name= orderID
Northwind
QueryStringField= ID />
Database
</SelectParameters>
demo
Filtering and Master-Details
Bradley Millington
Program Manager
Web Platform and Tools
Data Binding In Templates
• V1 data binding syntax too verbose
– <%# DataBinder.Eval(Container.DataItem, “field”
[,formatString]) %>
• Simplified data binding syntax in ASP.NET 2.0
– <%# Eval(“field” [,formatString]) %> // 1-way databinding
– <%# Bind(“field” [,formatString]) %> // 2-way databinding
• New two-way data binding syntax
– Enables templated controls to retrieve input values,
passed to automatic updates, inserts, deletes
– Supported in GridView, DetailsView controls (TemplateField)
– Support in new FormView control (fully-templated DetailsView)
– Not supported for DataList (V1 control)
demo
Data Binding in Templates
Bradley Millington
Program Manager
Web Platform and Tools
Caching Data
• Caching is a best practice, but many developers
don’t do this – it’s too hard in V1!
• Data sources can automatically cache data
– Manages cache key and dependencies for you
– Completely transparent to data-bound controls
<asp:ObjectDataSource …
EnableCaching=“true”
CacheDuration=“[time in seconds]”
CacheExpirationPolicy=“[absolute|sliding]”
CacheKeyDependency=“Customers”
SelectMethod=“GetCustomers”
TypeName=“CustomersDB”
runat=“server” />
• Can also manage caching yourself in business
object layer
SQL Cache Invalidation
• Retains cache entry until database table changes
– Only invalidates when backend data is stale
• Built on SQL Server 2005 notifications
– Supported on SQL7, SQL2k, or SQL Express via polling
• Enabled with SqlCacheDependency property on
OutputCache directive and data source controls
– SqlDataSource supports notifications or polling
– ObjectDataSource supports polling only
• Can use still use notifications in DAL/BLL code
<asp:SqlDataSource …
EnableCaching=“true”
CacheDuration=“Infinite”
SqlCacheDependency=
“conn:table|CommandNotification”
demo
Data Source Caching
Bradley Millington
Program Manager
Web Platform and Tools
Hierarchical Data
• Hierarchical data sources
– Expose data as parent-child relationships
– <asp:XmlDataSource/>
– <asp:SiteMapDataSource/>
• Hierarchical data-bound controls
– Use a navigator to walk the tree structure
– <asp:TreeView/>
– <asp:Menu/>
• Can also bind tabular (list) controls to
hierarchical data
– Only top-level data items are rendered
Hierarchical Data
• Can also bind to XML in a template
– Can bind anywhere in the hierarchy
• New XPath databinding syntax
– XPath(“books/genre/@name”)
– Returns simple value, e.g., “Fiction”
• New XPathSelect syntax
– XPathSelect(“books/genre[@name=‘Fiction’]”)
– Returns a list, e.g., IEnumerable of book elements
– Can be enumerated directly, or bound to the
DataSource property of a list control
demo
Binding to Hierarchical Data
Bradley Millington
Program Manager
Web Platform and Tools
Summary
• Visual Web Developer Express and SQL Server
Express make it easy to build data-driven apps!
• ASP.NET 2.0 data source controls dramatically
simplify data-binding over v1.x
• Integrates easily with middle-tier data
components and business objects
• Retains the flexibility of v1.x for complex
scenarios requiring code
• Provides a model that third-party data providers
can easily extend
Resources
• My Slides and Demos
– http://www.bradmi.net/presentations
• ASP.NET 2.0 Quickstarts
– http://www.asp.net/quickstart
• ASP.NET Forums
– http://www.asp.net/forums
• Nikhil Kothari's Blog
– http://www.nikhilk.net