[Laszlo-user] Help with replicators ("__LZdepChildren has no properties")

[P T Withington]

On 2007-07-16, at 23:48 EDT, Yang wrote:

> Now, things works fine in Flash. However, in DHTML, if I change the
> dataset's columns so as to trigger re-execution this code, I get an
> error on the line I labeled above. The error is:
>
> ERROR: http://localhost:8080/lps-4.0.2/lps/includes/lfc/LFCdhtml- 
> debug.js:12699:
> this.__LZdepChildren has no properties
>
> This one really has me stumped. 'replicator' seems to exist, yet I'm
> not able to remove it. I have no idea what this error message is
> talking about, and the source it's referring me to is indecipherable
> (I'm guessing it's generated from the lfc sources in subversion). Any
> help?

What you are seeing is an uncaught error in the runtime that is being  
handled by the last resort error handler.  The line number refers to  
the compiled LFC.  If you inspect that file at that line, you can  
search back for a comment of the form:

/* -*- file: data/LzDatapointer.lzs#268.27 -*- */

which will give you the source file.  Hm.  That is not right.  I  
looks like these comments are being dropped in some cases.  http:// 
jira.openlaszlo.org/jira/browse/LPP-4298

But poking around in the sources I can see that your error is  
occurring in LzDatapath's destroy method:

@@ -381,7 +387,8 @@
      //if immediate parent was deleted, don't worry about the  
datpaths dependent
      //on this one -- they'll be deleted too
      if ( ! this.immediateparent.__LZdeleted ){
-        if ( this.__LZdepChildren.length ){
+        if ( this.__LZdepChildren != null &&
+             this.__LZdepChildren.length ){
              //need to assign __LZdepChildren to parent
              var dnpar = this.immediateparent.searchParents 
( "datapath" ).
                                                                       
datapath;

http://jira.openlaszlo.org/jira/browse/LPP-4299