This example shows the advanced hierarchy model of Telerik RadGrid. You can set the table relations declaratively or programmatically through the
GridTableView.ParentTableRelation
property. Each entry in this collection consists of a relation key names. These key names have to be also populated in each GridTableView
DataKeyNames array.
When these properties are specified correctly, Telerik RadGrid will be able to determine the child records of each GridTableView when the control builds the hierarchy, without handling the DetailTableDataBind event.
In order to achieve this you must set the
ParentTableRelation property of every detail table view to indicate how its data table links to the parent table view's data table.
ParentTableRelation is a collection of
GridRelationFields objects. Each object specifies the link between a single field in the detail table and the corresponding field in the parent table.
It does this using two properties:
- The MasterKeyField property is the name of a field in the data source of the parent table. This property must match exactly a string in the DataKeyNames collection of the parent table view.
- The DetailKeyField property is the name of a field in the data source of the child table whose value must match the parent field specified by MasterKeyField.
If you are using declarative data sources, this string must match exactly the name of a SELECT parameter in the detail table view's data source.
To summarize, you need to define the
ParentTableRelations/DataKeyNames for the
MasterTableView/GridTableViews according to the database relations conventions.
And here are the exact conventions:
- the primary key column name for each table in the grid source (used for master/detail table population) should be added to the DataKeyNames collection of the respective master/detail table;
- the MasterKeyField in the GridRelationFields should match the primary key of the parent table in the corresponding relation;
- the DetailKeyField in the GridRelationFields should match the foreign key of the child table in the corresponding relation.
There is one more detail if you use declarative binding using
DataSource controls under .NET 2.x/3.x:You should have
WHERE clause in the
SelectCommand of the second DataSource
control which to filter the records for the child table. The
WHERE clause should include the
DetailKeyField from the
ParentTableRelation definition between the master/child table.
Furthermore, that same field has to be included in the
SelectParameters of the second DataSource (with exactly the same
Name value)
An important detail is that every
GridRelationFields
should have only one field name for
DetailKeyField and
MasterKeyField. For multi-hierarchy relations you can use multiple relation fields as in the example below:
<ParentTableRelation>
<telerik:GridRelationFields DetailKeyField="ID1" MasterKeyField="ID1" />
<telerik:GridRelationFields DetailKeyField="ID2" MasterKeyField="ID2" />
<telerik:GridRelationFields DetailKeyField="ID3" MasterKeyField="ID3" />
</ParentTableRelation>
Note that hierarchical grid structure is not supported with simple data-binding (calling DataBind()). See the
Simple data binding demo from the
Populating with data
section for more info about the limitations of this binding mode.
You can also check out the different load modes of the grid by changing the setting at the top of the demo