After creating the T-Shirt form bean, we'll add some validation on the T-shirt form data. In this tutorial, we will add a restriction on the T-shirt text's length while allowing any type of character:

1. In com.extensions.tshirt.sfweb.formbean, create a new package named validator.impl
2. In com.extensions.tshirt.sfweb.formbean.validator.impl, create a Java class named TshirtFormBeanValidator and add the following code below:

                  CoreTutorial2/tutorial2-ext-storefront/src/main/java/com/extensions/tshirt/sfweb/formbean/validator/impl/TshirtFormBeanValidator.java
   package com.extensions.tshirt.sfweb.formbean.validator.impl;
   
   import java.util.Map;
   
   import com.extensions.tshirt.sfweb.formbean.ExtShoppingItemFormBean;
   import com.extensions.tshirt.sfweb.formbean.TshirtFormBean;
   
   import org.owasp.esapi.ESAPI;
   import org.springframework.validation.Errors;
   
   import com.elasticpath.sfweb.formbean.ShoppingItemFormBean;
   import com.elasticpath.sfweb.formbean.validator.impl.ProductFormBeanValidator;
   
   /**
    * Validates {@link TshirtFormBean} data.
    */
   public class TshirtFormBeanValidator extends ProductFormBeanValidator {
   
   	private static final String ESAPI_ANYTHING_VALIDATOR = "Anything";
   	private static final int FRONT_MAX_LEN = 100;
   	private static final int BACK_MAX_LEN = 100;
   
   	private Map<String, String> errorCodeMap;
   
   	/**
   	 * {@inheritDoc}
   	 *
   	 * Ensures the T-Shirt's front and back text are not greater than 100 characters.
   	 */
   	public void validate(final ShoppingItemFormBean formBean, final Errors errors,
   							final int shoppingItemIndex) {
   
   		// validate quantity
   		super.validate(formBean, errors, shoppingItemIndex);
   
   		// validate t-shirt front and back text lengths
   		ExtShoppingItemFormBean extShoppingItemFormBean = (ExtShoppingItemFormBean) formBean;
   		TshirtFormBean tshirtFormBean = extShoppingItemFormBean.getTshirtFields();
   
   		validateFrontText(tshirtFormBean, errors, shoppingItemIndex);
   		validateBackText(tshirtFormBean, errors, shoppingItemIndex);
   	}
   
   	private void validateFrontText(final TshirtFormBean tshirtFormBean, final Errors errors,
   									final int shoppingItemIndex) {
   		String prefix = "cartItems[" + shoppingItemIndex + "].tshirtFields.";
   
   		boolean frontTextisValid = ESAPI.validator().isValidInput("tshirt_frontText",
   				tshirtFormBean.getFrontText(), ESAPI_ANYTHING_VALIDATOR, FRONT_MAX_LEN, true);
   
   		if (!frontTextisValid) {
   			addError(prefix + "frontText", getErrorCodeMap().get("errorFrontTextSize"), errors);
   		}
   	}
   
   	private void validateBackText(final TshirtFormBean tshirtFormBean, final Errors errors,
   									final int shoppingItemIndex) {
   		String prefix = "cartItems[" + shoppingItemIndex + "].tshirtFields.";
   
   		boolean backTextisValid = ESAPI.validator().isValidInput("tshirt_backText",
   				tshirtFormBean.getBackText(), ESAPI_ANYTHING_VALIDATOR, BACK_MAX_LEN, true);
   
   		if (!backTextisValid) {
   			addError(prefix + "backText", getErrorCodeMap().get("errorBackTextSize"), errors);
   		}
   	}
   
   	public Map<String, String> getErrorCodeMap() {
   		return errorCodeMap;
   	}
   
   	public void setErrorCodeMap(final Map<String, String> errorCodeMap) {
   		this.errorCodeMap = errorCodeMap;
   	}
   }
               

3. In ext-storefront-webapp/src/main/webapp/WEB-INF/security/ESAPI.properties, add the following property at the end of the file:

   Validator.Anything=^.*$
   

   The TshirtFormBeanValidator will use this regular expression to allow any character in the front and back text fields.