[Laszlo-user] [Laszlo-dev] How to retrieve list elements

[André Bargull]

Hi Chen,

this should work for you.
Changes:
- using "toggleselected" on the list
- using a handler to listen for "onselected" events from the list to 
disable/enable delete btn
- using "getNumItems" and "getItemAt" to retrieve the list items

---
<canvas height="550" debug="true">
    <simplelayout spacing="10"/>
   
    <dataset name="dsMyWishList">
        <wishes>
            <wish>Constraints are wonderful but I wish they work</wish>
            <wish>I can retrieve list elements</wish>
        </wishes>
    </dataset>

    <list id="mylist" width="200" height="82" toggleselected="true" >
        <textlistitem datapath="dsMyWishList:/wishes/wish/text()" />
    </list>
   
    <button text="Delete" enabled="false" >
        <handler name="onselect" reference="mylist" >
            this.setAttribute("enabled", mylist.getSelection() != null);
        </handler>
    </button>

    <button text="Test">
        <handler name="onclick"><![CDATA[
            Debug.write("Number of subviews: ", mylist.getNumItems());
            for (var i = 0; i < mylist.getNumItems(); ++i) {  
                Debug.write("The element: ", mylist.getItemAt(i));
            }
        ]]></handler>
    </button>
</canvas>
---

> Hi There, 
>
> I am trying to use the list component in my GUI. After a day of struggling, I guess I have to seek help from the professionals. 
>
> First of all, I need to retrieve all the elements from the list, but found no way to get them (unless I program it myself). Tried to use the 'subviews' array but it does not seem giving me what I wanted. I am wondering whether there is an easy way to get the elements of a list. 
>
> Second, I am trying to use the constraint between a "Delete" button and the selectionmanager so that the delete button will be enabled if and only if there is one selection on the list. But, it does not seem working. 
>
>
> Below is the simplified code. 
>
> Your help is greatly appreciated!
>
> Chen Ding
>
> ================ Example ==============================
>
>   1 <canvas height="550" debug="true">
>   2     <simplelayout spacing="10"/>
>   3     <dataset name="dsMyWishList">
>   4         <wishes>
>   5             <wish>Constraints are wonderful but I wish they work</wish>
>   6             <wish>I can retrieve list elements</wish>
>   7         </wishes>
>   8     </dataset>
>   9 
>  10     <list id="mylist" width="200" height="82">
>  11         <selectionmanager name="selector" toggle="true"/>
>  12         <textlistitem datapath="dsMyWishList:/wishes/wish/text()" onclick="mylist.selector.select(this)"/>
>  13     </list>
>  14 
>  15     <simplelayout axis="y"/>
>  16     
>  17     <!-- Wish 1: use the constraint to enable/disable the delete button. The button indeed -->
>  18     <!--         was disabled initially, but is never enabled even when I selected an      -->
>  19     <!--         in the list.                                                              -->
>  20     <button text="Delete" enabled="${mylist.selector.selected == 1}"/>
>  21     
>  22     <!-- Wish 2: can retrieve list elements. The only way I can find is through 'subviews' -->
>  23     <!--         but it does not seem working                                              -->
>  24     <button text="Test">
>  25         <handler name="onclick">
>  26         <![CDATA[
>  27             Debug.write("Number of subviews: ", mylist.subviews.length);
>  28             for (var i=0; i<mylist.subviews.length; i++)
>  29             {   
>  30                 Debug.write("The element: ", mylist.subviews[i]);
>  31             }
>  32         ]]>
>  33         </handler>
>  34     </button>
>  35 </canvas>
>
>
>
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