Lift

Question

I would like to use an autocomplete with ajax. So my goal is to have:

When the user types something in the text field, some suggestions provided by the server appear (I have to find suggestions in a database)
When the user presses "enter", clicks somewhere else than in the autocomplete box, or when he/she selects a suggestion, the string in the textfield is sent to the server.

I first tried to use the autocomplete widget provided by lift but I faced three problems:

it is meant to be an extended select, that is to say you can originally only submit suggested values.
it is not meant to be used with ajax.
it gets buggy when combined with WiringUI.

So, my question is: How can I combine jquery autocomplete and interact with the server in lift. I think I should use some callbacks but I don't master them.

Thanks in advance.

UPDATE Here is a first implementation I tried but the callback doesn't work:

private def update_source(current: String, limit: Int) = {   
  val results = if (current.length == 0) Nil else /* generate list of results */
  new JsCmd{def toJsCmd = if(results.nonEmpty) results.mkString("[\"", "\", \"", "\"]") else "[]" }
}   

def render = {
  val id = "my-autocomplete"
  val cb = SHtml.ajaxCall(JsRaw("request"), update_source(_, 4))
  val script = Script(new JsCmd{
    def toJsCmd = "$(function() {"+
      "$(\"#"+id+"\").autocomplete({ "+
      "autocomplete: on, "+
      "source: function(request, response) {"+
        "response("+cb._2.toJsCmd + ");"  +
      "}"+
      "})});"
  })

  <head><script charset="utf-8"> {script} </script></head> ++
  <span id={id}> {SHtml.ajaxText(init, s=>{ /*set cell to value s*/; Noop}) }   </span>
}

So my idea was:

to get the selected result via an SHtml.ajaxText field which would be wraped into an autocomplete field
to update the autocomplete suggestions using a javascript function

Dave Whittaker · Accepted Answer

Here's what you need to do.

1) Make sure you are using Lift 2.5-SNAPSHOT (this is doable in earlier versions, but it's more difficult)

2) In the snippet you use to render the page, use SHtml.ajaxCall (in particular, you probably want this version: https://github.com/lift/framework/blob/master/web/webkit/src/main/scala/net/liftweb/http/SHtml.scala#L170) which will allow you to register a server side function that accepts your search term and return a JSON response containing the completions. You will also register some action to occur on the JSON response with the JsContext.

3) The ajaxCall above will return a JsExp object which will result in the ajax request when it's invoked. Embed it within a javascript function on the page using your snippet.

4) Wire them up with some client side JS.

Update - Some code to help you out. It can definitely be done more succinctly with Lift 2.5, but due to some inconsistencies in 2.4 I ended up rolling my own ajaxCall like function. S.fmapFunc registers the function on the server side and the function body makes a Lift ajax call from the client, then invokes the res function (which comes from jQuery autocomplete) on the JSON response.

My jQuery plugin to "activate" the text input


(function($) {
    $.fn.initAssignment = function() {
     return this.autocomplete({
         autoFocus: true,
         source: function(req, res) {
              search(req.term, res);
         },
         select: function(event, ui) {
             assign(ui.item.value, function(data){
                eval(data);
             });
             event.preventDefault();
             $(this).val("");
         },
         focus: function(event, ui) {
             event.preventDefault();
         }
     });
    }
})(jQuery);

My Scala code that results in the javascript search function:


def autoCompleteJs = JsRaw("""
        function search(term, res) {
        """ +
             (S.fmapFunc(S.contextFuncBuilder(SFuncHolder({ terms: String =>
                val _candidates = 
                  if(terms != null && terms.trim() != "")
                    assigneeCandidates(terms)
                  else
                    Nil
                JsonResponse(JArray(_candidates map { c => c.toJson }))
             })))
             ({ name => 
               "liftAjax.lift_ajaxHandler('" + name 
             })) + 
             "=' + encodeURIComponent(term), " +
             "function(data){ res(data); }" +
             ", null, 'json');" +
        """
        }
        """)

Update 2 - To add the function above to your page, use a CssSelector transform similar to the one below. The >* means append to anything that already exists within the matched script element. I've got other functions I've defined on that page, and this adds the search function to them.


"script >*" #> autoCompleteJs

You can view source to verify that it exists on the page and can be called just like any other JS function.

Lift - Autocomplete with Ajax Submission

Tags:

callback

scala

jquery-ui

Christopher Chiche

1 Answers

Dave Whittaker

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