The double range field validator checks if a float/double field falls within a specified range. We can use this validator in either XML or annotation:

• • XML: specifying type=”double” attribute for <validator> or <field-validator> elements.
  • Annotation: specifying @DoubleRangeFieldValidator annotation type before field’s setter method or action method (plain-validator).

The range can be inclusive or exclusive. For example, if we specify a range of [10, 50] for a number x, then:

• • an inclusive range means: 10 <= x <= 50
  • an exclusive range means: 10 < x < 50

 

1. Struts Double Range Field Validator XML Syntax:

Usage:

• Field-validator syntax:
  

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

   

• Plain-validator syntax:
  

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

 

Parameters:

Parameter name	Required	Description
fieldName		Name of the field (required if using plain validator syntax).
minInclusive	No	The minimum inclusive value to check. It won’t be checked if omitted.
maxInclusive	No	The maximum inclusive value to check. It won’t be checked if omitted.
minExclusive	No	The minimum exclusive value to check. It won’t be checked if omitted.
maxExclusive	No	The maximum exclusive value to check. It won’t be checked if omitted.
minInclusiveExpression	No	OGNL expression to calculate the minimum inclusive value. It won’t be evaluated if omitted.
maxInclusiveExpression	No	OGNL expression to calculate the maximum inclusive value. It won’t be evaluated if omitted.
minExclusiveExpression	No	OGNL expression to calculate the minimum exclusive value. It won’t be evaluated if omitted.
maxExclusiveExpression	No	OGNL expression to calculate the maximum exclusive value. It won’t be evaluated if omitted.

 

Struts Double Range Field Validator XML Examples:

• Field-validator example using inclusive range check:

  <field name="scale">
  	<field-validator type="double">
  		<param name="minInclusive">0.5</param>
  		<param name="maxInclusive">10.5</param>
  		<message>The scale must bet between ${minInclusive} and ${maxInclusive} (inclusive)</message>
  	</field-validator>
  </field>

• Field-validator example using exclusive range check:

  <field name="scale">
  	<field-validator type="double">
  		<param name="minExclusive">0.5</param>
  		<param name="maxExclusive">10.5</param>
  		<message>The scale must be between ${minExclusive} and ${maxExclusive} (exclusive)</message>
  	</field-validator>
  </field>

• Only checking the minimum value:

  <field name="scale">
  	<field-validator type="double">
  		<param name="minInclusive">5.2</param>
  		<message>The scale must be equal or greater than ${minInclusive}</message>
  	</field-validator>
  </field>

• Using OGNL expressions:

  <field name="scale">
  	<field-validator type="double">
  		<param name="minExclusiveExpression">${minExclusiveValue}</param>
  		<param name="maxExclusiveExpression">${maxExclusiveValue}</param>
  		<message>The scale must be between ${minExclusive} and ${maxExclusive} (exclusive)</message>
  	</field-validator>
  </field> 

  In this case, the action class or the JavaBean class must implement the following methods (for example):

  public double getMinExclusiveValue() {
  	return 11.5;
  }
  
  public double getMaxExclusiveValue() {
  	return 40.3;
  } 

• Plain-validator example:
  

  <validator type="double">
  	<param name="fieldName">scale</param>
  	<param name="minInclusive">0.5</param>
  	<param name="maxInclusive">10.5</param>
  	<message>The scale must bet between ${minInclusive} and ${maxInclusive} (inclusive)</message>
  </validator> 

 

2. Struts @DoubleRangeFieldValidator Annotation

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

@DoubleRangeFieldValidator(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).
minInclusive	No		The minimum inclusive value to check.
minInclusiveExpression	No		OGNL expression used to calculate the minimum inclusive value.
maxInclusive	No		The maximum inclusive value to check
maxInclusiveExpression	No		OGNL expression used to calculate the maximum inclusive value.
minExclusive	No		The minimum exclusive value to check.
minExclusiveExpression	No		OGNL expression used to calculate the minimum exclusive value.
maxExclusive	No		The maximum exclusive value to check.
maxExclusiveExpression	No		OGNL expression used to calculate the maximum exclusive value.

 

Struts @DoubleRangeFieldValidator Examples:

• Basic field-validator:
  

  @DoubleRangeFieldValidator(
  		minInclusive = "23.5", maxInclusive = "57.8",
  		message = "The scale must bet between ${minInclusive} and ${maxInclusive} (inclusive)"
  		)
  public void setScale(double scale) {
  	this.scale = scale;
  }

   

• Specifying i18n key for the message:
  

  @DoubleRangeFieldValidator(
  		minInclusive = "23.5", maxInclusive = "57.8",
  		message = "Default message",
  		key = "form.validation.scale"
  		)
  public void setScale(double scale) {
  	this.scale = scale;
  }

   

• Plain-validator (annotating the action method):
  

  @DoubleRangeFieldValidator(
  		type = ValidatorType.SIMPLE,
  		fieldName = "scale",
  		minExclusive = "20.5",
  		maxExclusive = "78.5",
  		message = "The scale must be between ${minExclusive} and ${maxExclusive} (exclusive)"
  		)
  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 Short Range Field Validator Example
• Struts String Length Field 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