WebWork 2 Ajax Validation

Validation servlet vs Interceptor

• Using a validation servlet requires the app developer to map any servlet filters for any action that is to be validated to the validation servlet as well.
• Using a validation interceptor executes the validation within the context of any mapped servlet filters, as well as within the context of the action.

Custom Ajax code or Third Party Library

• The DOJO Toolkit promises to be a very flexible and powerful toolkit, however they are only ion the beginning stages. A lot of the code is coming from other dhtml toolkit projects that are very mature.
• We only require a fairly simple xmlhttp layer a the moment. Dojo have released their dojo.io.bind package http://dojotoolkit.org/intro_to_dojo_io.html which should be sufficient for us, however I think we can produce our own XmlHTTP code for now.
• I have implemented some custom xmlhttp / javascript code http://www.drivelater.com.au - do a search. It works in IE and FireFox.

Should webwork provide a static resource loader

• We need to provide a developer friendly way of exposing webwork static resources - primarily javascript files

• 1. User could copy them into a folder
     • This either requires a separate zip download or packaging these files within the jar
     • This is a bad idea because it is error prone when the user upgrades

• 1. Provide a resource loading servlet that serves the resources from the webwork jar
     requires a servlet definition and mapping in web.xml
     • could use a webwork.properties setting for the servlet prefix to allow user to 'mount' the static resources under a different prefix
       this makes jar upgrades easy and transparent
     • I have a prototype of this working in one of my apps - however it is restricted to mounting a single package on a single prefix. No support for multiple mappings.

       i.e.  mount com.opensymphony.webwork.static at /webwork 
       request /webwork/validationAjax.js 
       loads  com.opensymphony.webwork.static.validationAjax.js
       

  2. Get the validationServlet to serve the javascript code. Use '/validationServlet/client.js' as the url

• 1. Any other ideas ?

Supported Browsers

• We need to define what browsers we will support.

JavaScript API

• In webwork CVS /src/webapp/validationServlet.js contains a sample ValidationServlet client javascript class. It handles the communication with the validation servlet, and exposes callbacks for handling the errors. NOTE : I think we can re-work this a bit. I currently have lots of onWhatever callbacks. I think we should just have onErrors, and let the template designer do what they want with the Errors object.
  • Sample Usage

    var validation = new ValidationServlet('/validationServlet/client.js');
    validation.onErrors = function(inputObject, errors) {
    	// clear old errors
    	// display new errors
    }
    

  • The errors param for the onErrors callback is a javascript object that has this structure

    class Errors {
    	String[] actionErrors;
    	Map<String, String[]> fieldErrors; // fieldName is the key
    }
    

• See this in action in webwork cvs head

   
  /src/java/templates/xhtml/validation.vm
  /src/webapp/validationServlet.js
  /src/webapp/javascript-input.jsp
  

• Cloves' provided example API :

  function addError(fieldName, messages); // should messages be an array?!
  function clearError(fieldName);
  function clearErrors(formName);
  

New WebWork theme

• We need to develop a new slick looking template based on css that has full client side javascript support.
• We could mix some ideas from
  • http://www.themaninblue.com/experiment/InForm/margin.htm
  • http://www.baekdal.com/articles/Usability/usable-XMLHttpRequest/