Use data source controls
🚧 Important This topic applies to sites using Web Forms.
One of the more influential groups of controls included in Optimizely Content Management System (CMS) is the data source controls. One of the major benefits of using these controls is that they minimize the need for code-behind for day-to-day operations involving reading data and populating various lists, trees, and so on. The controls support all or a few of the select, insert, update, and delete operations.
Some benefits of using the controls are:
- Minimized need for plumbing code in code-behind.
- Built-in support for selecting, inserting, updating, and deleting.
- A contract that fits many of the built-in .NET controls and third-party controls.
You can categorize the data source controls as Hierarchical, Tabular, or both, depending on how they can deliver data.
- Hierarchical data source controls expose data in a hierarchical fashion (parent-child), which you can use for tree views such as the TreeView and Menu controls in ASP.NET.
- Most controls serve data in a tabular fashion, which you can use to list controls such as the Repeater, DataList, GridView, and so on.
📘 Note An important difference between hierarchical and tabular data sources are that hierarchical data sources are read-only whereas the tabular data sources can support inserting, updating, and deleting.
The following controls implement the IHierarchicalDataSource interface and can generate data for tree view controls or menus:
- PageDataSource
- CategoryDataSource
- FileSystemDataSource
To create your own tabular data source controls, use the base class GenericDataSource.
Use a CMS data source control
You should use the data source classes in markup. You should not code against or inherit from them, so you should not need to add your code-behind. If you do need additional functionality, you should inherit from the GenericDataSource control and create classes that suit your needs.
The data source controls work as any standard control in an .aspx page.
Element attribute and query parameter
When you populate a data source, you usually use a QueryStringParameter to read a selection of objects from the database. You can define a value for a member of the object as an attribute in the asp element and as a parameter in the query string. In this case, the query string definition precedes the asp attribute. Consider the following example:
<EPiServer:CategoryDataSource
runat="server"
ID="CategoryData"
IncludeRootCategory="true">
<SelectParameters>
<asp:QueryStringParameter
Name="ID"
QueryStringField="ID"
Type="Int32" />
<asp:QueryStringParameter
Name="IncludeRootCategory"
QueryStringField="IncludeRootCategory"
Type="Boolean"
DefaultValue="false" />
</SelectParameters>
</EPiServer:CategoryDataSource>Because IncludeRootCategory is defined twice (being set to true in the tag definition and false in the QueryStringParameter), the value set in the query string parameter is used. If no query string parameter named IncludeRootCategory is specified, it is the default value that is used, in this case, false. For information about using parameters with Data Source Controls, see Microsoft’s article Using Parameters with Data Source Controls.
📘 Note You should not use certain words to use as parameter names for http requests. For example, ID causes a conflict if you try to use it as a parameter name for one of your http requests, because ID is used to identify aspx pages in CMS. If the page had an ID of 200, every call to the CategoryDataSource would try to fetch categories with a parent ID of 200. You can solve the issue by adding text to certain words, such as changing ID to CategoryID.
Create data source controls
Designing data source controls is a matter of inheriting from the GenericDataSource class. The following lines of code show how the TabDefinitionDataSource is defined. There is little code involved in getting access to the basic functionality.
public class TabDefinitionDataSource:
GenericDataSource<TabDefinition, TabDefinitionCollection, int> {
protected override TabDefinition CreateItem(List<TabDefinition> items) {
return new TabDefinition();
}
protected override List< TabDefinition> ListItems() {
return ToList(TabDefinition.List());
}
protected override TabDefinition LoadItem(int key) {
return TabDefinition.Load(key);
}
protected override void SaveItem(TabDefinition item) {
item.Save();
}
protected override void DeleteItem(TabDefinition item) {
item.Delete();
}
}GenericDataSource<TObject, TCollection, TKey> has the following type parameters:
Name | Explanation | Example |
|---|---|---|
TObject | The business object type | TabDefinition |
TCollection | A collection type that holds objects of type TObject | TabDefinitionCollection or List<TabDefinition> |
TKey | The data type of the primary key | int |
Business Objects Before creating your data source control type, have a class, your business object, that handles the data you want to present. In the sample above, the class used for this is TabDefinition. This class is responsible for reading and saving data from the database.
Suppose you do not need to implement a specialized behavior in your collection of business objects. In that case, you can use the generic List provided by the .NET Framework as described in the following short sample:
...
...
public class MyObjectDataSource :
GenericDataSource<MyObject, List<MyObject>, int>
{
...
...Map between control properties and data source parameters
A common way to limit a result set of a data source control is to provide its parameters in the SelectParameters collection (see Parameter), which most CMS data source controls support by allowing overrides of certain control properties by a parameter value. You can specify the following properties using Parameters for a given CMS data source control. The parameter name must correspond to the property name.
PageDataSource
- AccessLevel – EPiServer.Security.AccessLevel
- PageLink – EPiServer.Core.PageReference
- PageLinkProperty – String
- IncludeRootPage – Bool
SearchDataSource
- AccessLevel – EPiServer.Security.AccessLevel
- PageLink – EPiServer.Core.PageReference
- PageLinkProperty – String
- IncludeRootPage – Bool
- OnlyWholeWords – Bool
- SearchQuery – String
- SearchFiles – Bool
- SearchLocations – String
- MainCatalog – String
- MainScope – String
- MaxAllowHits – Integer
CategoryDataSource
- IncludeRootCategory – Bool
FileSystemDataSource
LanguageDataSource
PageDefinitionDataSource
- Dynamic – Bool
- PageTypeID – Integer
PageDefinitionTypeDataSource
- ID – Integer
TabDefinitionDataSource
- ID – Integer
MembershipUserDataSource
- UserName – string
SoftLinkDataSource
- PageLink – EPiServer.Core.PageReference
- ListReferencing – Bool