List Field - ASP.NET DropDownList with validation
List Field is an ASP.NET Web control rendered as a labeled drop down list that allows user
to select, display and validate a single item from the drop down list.
Implementation
List Field is implemented by the ListField class.
Documentation
Click here to see the documentation
of the ListField class.
Validations
List Field supports validations in the following execution order.
- Not null validation
- Regular expression validation
- Compare to value validation
- Compare to control validation
- Custom validation
Custom Validation
List Field supports custom validation at both client-side and server-side. To setup
the custom validation error message, use the ListField.CustomValidation.Message property;
to setup client-side custom validation, use the ListField.CustomValidation.ClientValidator
property to specify the name of a JavaScript function that is used to perform client-side custom validation;
to setup server-side custom validation, handle the server-side CustomValidate event.
The custom client validator function must take one parameter which in run-time will receve the
validation context as a JSON object in the following format:
{"source":dropDownListId, "data":selectedItem, "callback":callbackFunction}.
Here the "source" contains the id of the drop down list; "data" is a JSON object that contains
the data of the selected item in this format: {"index":selectedIndex, "value":selectedValue, "text":selectedText};
"callback" contains a function that can be used during asynchronous custom validation
to notify the XField's Client Validation Engine about the result of the validation.
To perform synchronous custom validation, add validation logic in the custom client validator you
provide, and return a boolean value to indicate whether the field data passes the validation or not.
To perform asynchronous (Ajax) custom validation, first save the callback function somewhere
(typically in a global variable); then setup Ajax call to the server-side to handle custom validation.
After the Ajax call completes, notify the XField's Client Validation Engine about the result of
the validation by invoking the saved callback with a boolean value to indicate whether the
field data passes the validation or not.
View Custom Validation Demo of List Field.
Go to top