The required field validator in Struts can be used to check if field is non-null. It can be used in either of the following forms:

• • XML: using type=”required” attribute in <validator> or <field-validator> elements.
  • Annotation: using @RequiredFieldValidator annotation type to annotate setter method of the field or action method (plain-validator).

One example usage of this validator is to validate a field whose value is pulled from a dropdown list which may contain no items (the items are generated dynamically).

 

1. Struts Required Field Validator XML

Usage:

• Field-validator syntax:
  

  <field name="fieldName">
  	<field-validator type="required">
  		<message>validation error message</message>
  	</field-validator>
  </field>

   

• Plain-validator syntax:
  

  <validator type="required">
  		<param name="fieldName">myField</param>
  		<message>validation error message</message>
  </validator>

   

Parameters:

Parameter name	Description
fieldName	Name of the field to validate. Required if using plain validator syntax.

 

Struts Required Field Validator XML Examples:

• Field-validator example:
  

  <field name="myJob">
  	<field-validator type="required">
  		<message>You must specify your job.</message>
  	</field-validator>
  </field>

   

• Plain-validator example:
  

  <validator type="required">
  	<param name="fieldName">myJob</param>
  	<message>Please specify your current job.</message>
  </validator> 

  

2. Struts @RequiredFieldValidator Annotation

Usage: Put the @RequiredFieldValidatorannotation before the setter method or action method (in case of using plain-validator) in the following form:

@RequiredFieldValidator(param1 = "param 1 value", param2 = "param 2 value", ...)

Parameters:

Parameter name	Required	Default value	Description
message	Yes		validation error message.
key	No		i18n key for validation error message.
messageParams	No		Additional parameters to customize the message.
fieldName	No		Specifies field name in case this validator type is plain-validator.
shortCircuit	No	false	Whether this validator is short circuit.
type	No	ValidatorType.FIELD	type of the validator: field-validator (FIELD) or plain-validator (SIMPLE).

 

Struts @RequiredFieldValidator Examples:

• Basic field-validator:
  

  @RequiredFieldValidator(message = "Please specify your current job.")
  public void setMyJob(String myJob) {
  	this.myJob = myJob;
  }

   

• Specifying i18n key for the message:
  

  @RequiredFieldValidator(message = "Default message", key = "form.validation.job")
  public void setMyJob(String myJob) {
  	this.myJob = myJob;
  }

   

• Plain-validator (annotating the action method):
  

  @RequiredFieldValidator(type = ValidatorType.SIMPLE,
  	message = "Please specify your current job.",
  	fieldName = "myJob")
  public String execute() {
  	return SUCCESS;
  } 

 

Related Struts Form Validation Tutorials:

• Struts Form Handling Tutorial
• Struts Form Validation Tutorial
• Struts Date Range Field Validator Example
• Struts Integer Range Field Validator Example
• Struts String Length Field Validator Example
• Struts URL Validator Example
• Struts Field Expression Validator Example

 

Other Struts Tutorials:

• Introduction to Struts 2 framework
• Struts beginner tutorial (Eclipse + Tomcat + XML)
• Struts Beginner Tutorial with Annotations
• Struts beginner tutorial with Convention Plugin (zero-configuration)
• How to handle exceptions in Struts
• Send e-mail with attachments in Struts
• Struts File Upload Tutorial
• Struts - Spring - Hibernate Integration Tutorial