Databases Reference
In-Depth Information
LISTING 11.9
Continued
if (this.countryTemplate != null)
{
this.countryTemplate.AutoPostBack = true;
this.countryTemplate.DataBinding += this.CountryFieldValueChanged;
this.countryTemplate.FieldValueChanged += this.CountryFieldValueChanged;
}
}
protected override void ExtractValues(IOrderedDictionary dictionary)
{
dictionary[this.Column.Name] = this.ConvertEditedValue(this.textBox.Text);
}
protected void TextBox_TextChanged(object sender, EventArgs e)
{
this.OnFieldValueChanged(e);
}
private void CountryFieldValueChanged(object sender, EventArgs args)
{
this.Country = this.countryTemplate.FieldValueEditString;
}
}
}
The overridden
OnLoad
method passes the
CountryField
property value to the
FindOtherFieldTemplate
method provided by the base class,
FieldTemplateUserControl
,
to find the actual field template that was created for the
Country
property on the page. If
the country field template was found, its
AutoPostBack
property is set to
true
to make
sure that a post-back occurs when the user changes the country value and can update the
auto-completion list accordingly. The code also adds event handlers for the
DataBinding
and
FieldValueChanged
events of the country template.
The
DataBinding
event fires during initial rendering of the page, when the initial values of
the country and region properties are loaded from the database. The
FieldValueChanged
event fires during a post-back, when the user changes the country value on the page. In
both instances, you want to get the current value of the country field and use it to
provide a corresponding list of regions. As you recall from the discussion in Chapter 10,
the
Region
template uses the
AutoCompleteExtender
from the AJAX Control Toolkit to call
the
RegionCompletionService
method that provides the list of regions. The country value
serves as the
contextKey
in the web service call.
