About Mandatory Text and Conditional Mandatory Text

Canvas enables the developer to mark the item as mandatory or conditional mandatory enabling the developer to effectively handle user input.

For example:
Consider a case like making a Text Area (TXT_MESSAGE_DESC) as mandatory based on the check box (CHK_PROCEED_WOUT_MESG).
If the check box is selected, the user needs to enter values in the text area.

• If the check box is not selected, the user must enter values.

You can mark the TXT_MESSAGE_DESC as conditional mandatory and can write the cbxprevalidate as shown:
this.fm.registerHandler("cbxprevalidate", function(fm, config) {
//fm.getValue API is used to get the value of particular field.
if(fm.getValue("CHK_PROCEED_WOUT_MESG")=='Y')
{
//This API is used to marks a invalid field as Valid.
fm.clearInvalid("TXT_MESSAGE_DESC");
return [true, true];
}
else {
//This API is used to marks a invalid field as Valid.
fm.markInvalid("TXT_MESSAGE_DESC", "Please, Enter the message");
return false;
}
});
For more details of form APIs, see Form and Form Item APIs.
The form items are divided into five categories as follows:

• Data Entry
• Data Selection
• Toggle
• Action
• Display

Container items are divided into four categories as follows:

• Containers
• Fillers
• Information Fields
• Component