Description Field - ASP.NET Web control for long text data entry and validation
Description Field is an ASP.NET Web control rendered as a labeled HTML textarea tag that is used to
enter, display and validate long descriptional textual data.
Implementation
Description Field is implemented by the DescriptionField class.
Documentation
Click here to see the documentation
of the DescriptionField class.
Validations
Description Field supports validations in the following execution order.
- Not null validation
- Text length validation
- Regular expression validation
- Compare to value validation
- Compare to control validation
- Custom validation
Custom Validation
Description Field supports custom validation at both client-side and server-side. To setup
the custom validation error message, use the DescriptionField.CustomValidation.Message property;
to setup client-side custom validation, use the DescriptionField.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":textBoxId, "data":inputText, "callback":callbackFunction}.
Here the "source" contains the id of the text box; "data" contains the text of the text box;
"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 Description Field.
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