Struts Required String Validator Example

The Struts validation framework provides the required string validator in order to check a String field is not null and not empty (“”). It comes with two flavors:

• • XML: using type=”requiredstring” attribute in <validator> or <field-validator> elements.
  • Annotation: using @RequiredStringValidator annotation type to annotate setter method of the field.

1. Struts Required String Validator XML

Usage:

• Field-validator syntax:
  

  <field name="fieldName">
  	<field-validator type="requiredstring">
  		<param name="param name">param value</param>
  		<message>validation error message</message>
  	</field-validator>
  </field>

   

• Plain-validator syntax:
  

  <validator type="requiredstring">
  		<param name="param name">param value</param>
  		<message>validation error message</message>
  </validator> 

Parameters:

Struts Required String Validator XML Examples:

• Field-validator example:
  

  <field name="firstName">
  	<field-validator type="requiredstring">
  		<param name="trim">false</param>
  		<message>You must enter your first name</message>
  	</field-validator>
  </field>

   

• Plain-validator example:
  

  <validator type="requiredstring">
  	<param name="fieldName">firstName</param>
  	<param name="trim">false</param>
  	<message>You must enter your first name</message>
  </validator> 

2. Struts @RequiredStringValidator Annotation

Usage: Annotate setter method of the String field by:

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

Parameters:

Struts @RequiredStringValidator Annotation Examples:

• Basic field-validator:
  

  @RequiredStringValidator(message = "Please enter your first name")
  public void setFirstName(String firstName) {
  	this.firstName = firstName;
  }

   

• Specifying i18n key for the message:
  

  @RequiredStringValidator(message = "Default message", key = "form.validation.firstName")
  public void setFirstName(String firstName) {
  	this.firstName = firstName;
  }

   

• Plain-validator (annotating the action method):
  

  @RequiredStringValidator(type = ValidatorType.SIMPLE, fieldName = "firstName",
  	message = "Please enter your first name")
  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 Required Field 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

About the Author:

Nam Ha Minh is certified Java programmer (SCJP and SCWCD). He began programming with Java back in the days of Java 1.4 and has been passionate about it ever since. You can connect with him on Facebook and watch his Java videos on YouTube.