Re: Searching in a list of values (menulist, textbox)

Am 07.02.12 22:57, schrieb Michael Hofer:
>>> Not exactly what I want. Any ideas how to access/store the id of the
>>> selected entry for later retrieval (while displaying the displayValue)?
>>> Is there a way to access the textbox from within the
>>> 'ProviderAutoCompleteResult' (nsIAutoCompleteResult) to attach something
>>> like a 'selectedId' attribute to it?
>>
>> I'm now trying to use the comment field of the autocomplete textbox for
>> my id property (accessible via textbox.controller.getCommentAt(index)).
> [...]
>> Any ideas on how to get the selected index?
>
> I finally found a way. There is an 'autocomplete-did-enter-text'
> notification which can be observed. Because this notification is sent
> before the popup closes (as opposed to the ontextentered event), the
> index of the selected element is still available in the observer. So the
> comment (or other fields) from the chosen entry can be retrieved via
>
> subject.controller.getCommentAt(subject.popup.selectedIndex)

Somebody asked me for a code example for this. Here it is:

XUL (Autocomplete Textbox):
--------------------------------------------------------------
<panel id="kunde_popup_autocomplete" type="autocomplete" 
noautofocus="true" />
<textbox id="kunde"
          type="autocomplete"
          autocompletepopup="kunde_popup_autocomplete"
          autocompletesearch="json-autocomplete"
          completedefaultindex="true" forcecomplete="true"
          enablehistory="true"
          showcommentcolumn="true"
          autocompletesearchparam='[]'"/>

- The separate panel set via the autocompletepopup attribute on the 
textbox is not strictly necessary. But without it I got popup display 
problems in some places. Place the panel separately from the textbox 
(like on the top level of the document) if you've got display problems.

- "json-autocomplete" is my custom autosearch component implemented 
basically like described on 
https://developer.mozilla.org/en/How_to_implement_custom_autocomplete_search_component#Basic_example_for_Gecko_2.0_and_up_%28Firefox_4_.2F_Thunderbird_3.3_.2F_SeaMonkey_2.1%29

- The autcocompletesearchparam on the textbox is set via script on init 
to a string containing json encoded data (with the data key containing 
an an array of hashes each having fields for displayValue, comment, 
id,...) -> See http://pastebin.com/emg0nzWc for an according 
startSearch-implementation (autocompletesearchparam is received as 
searchParam there). In that implementation getValueAt(index) 
(nsIAutoCompleteResult) would return
   this.results[index]['displayValue']
while getCommentAt(index) would return
   this.results[index]['comment']
(or ['id'] if you used the comment field for the id)


Observer (for receiving the index of the selected entry)
----------------------------------------------------------

function myObserver()
{
   this.register();
}
myObserver.prototype = {
   observe: function(subject, topic, data) {
     var id = subject.controller.getCommentAt(subject.popup.selectedIndex);
     alert( 'id of selected element (read from comment field): ' + id );
   },
   register: function() {
     var observerService = 
Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
     observerService.addObserver(this, "autocomplete-did-enter-text", 
false);
   },
   unregister: function() {
     var observerService = 
Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
     observerService.removeObserver(this, "autocomplete-did-enter-text");
   }
};

var testObserver = new myObserver();

This will be called after autocomplete was at work (but before the popup 
closes, so the selectedIndex is still available here). There are more 
undocumented notifications like this in 
toolkit/components/autocomplete/nsAutoCompleteController.cpp: 
'autocomplete-will-enter-text', 'autocomplete-will-revert-text', 
'autocomplete-did-revert-text'


Improvements
----------------------------------------------------------------

It's generally a good idea to have the xulrunner or firefox source code 
available for reference when working on these less documented features. 
Also: Don't mess around too much with internals when you are not in 
control of your xulrunner-environment (like when writing plugins).

1) To implement additional fields (like a getIdAt(index)-function in 
your nsiAutoCompleteResult) it seems to be necessary to also extend 
(implement your own?) nsIAutoCompleteController. Without that, all you 
have available from the controller is comment, image, label/value and style.
I didn't do that yet. Code examples anyone?


2) The default panel associated with the autocomplete textbox uses a 
tree with two columns (one for the value, one for the comment) for 
display. Using a richlistbox gives better formatting options + free 
search string highlighting in the result list (similar to awesomebar in 
firefox). But

<panel id="kunde_popup_autocomplete" type="autocomplete-richlistbox" />

(as described in the tutorial) doesn't work properly for me (xulrunner 
2.0), but

<panel style="-moz-binding: 
url(chrome://global/content/bindings/autocomplete.xml#autocomplete-rich-result-popup)" 
id="kunde_popup_autocomplete" type="autocomplete" noautofocus="true" />

does (You'd better define a corresponding css class for that style).

To modify the structure of the individual richlistitems, you can extend 
the XBL:

XBL
----
<binding id="my-autocomplete-richlistitem" 
extends="chrome://global/content/bindings/autocomplete.xml#autocomplete-richlistitem">
     <content>
       <!-- copy/modify the content from 
chrome://global/content/bindings/autocomplete.xml#autocomplete-richlistitem 
here -->
     </content>
</binding>

CSS
---
.autocomplete-richlistitem {
   -moz-binding: 
url('/path/to/my-autocomplete.xml#my-autocomplete-richlistitem');
}

For modifying the popup (which is creating the 
autocomplete-richlistitems) also extend 
chrome://global/content/bindings/autocomplete.xml#autocomplete-rich-result-popup.

Hope this helps somebody.

regards,
Michael