[Zope] Re: [Support] [ZOPE Collector] Zope Question entry: Problems using Internet Explorer 5.5 as client brow

[Chris McDonough]

> Thanks for responding so quickly:

No problem!

> (1) I don't think I'm writing to the ZODB explicitly, the DTML
>     documents, that generate this error, call a number of ZSQL methods
>     that read (no inserts or updates are involved) data which is
>     then presented in tables. I'm not sure why the transaction
>     mechanism is involved with database reads, although I do see
>     an increase in the Data.fs file size so something is being
>     written. Maybe you could point me to some info that explains
>     when and why writes occur to the ZODB. This behavior has never

A write occurs any time __setattr__ is called on an object instance, or if
an attribute is set on an object named _p_changed and it's set to 1 (e.g.
self._p_changed = 1).  You can't use __setattr__ directly from DTML, but if
the DTML method calls an external method or a method of an object built-in
to Zope, any of these things can write to the ZODB directly.  In practice,
this generally occurs when adding DTML documents
(manage_addDTMLDocument(...)), DTML Methods (manage_addDTMLMethod(...)),
Folders, custom object instances, etc. from DTML.

>     occurred on the localhost connection where I'm using Netscape
>     as the client browser, nor has it ever occurred on a remote
>     connection when the browser was other than IE 5.5. I'm using

This is very odd.  I have no explanation for this.

>     ZPoPyDA to connect to PostgreSQL. The only other interesting
>     thing I'm doing is to set certain variables in the REQUEST based
>     upon each row coming back from the query. These variables are
>     then used to modify the layout for that row:
>
>     <dtml-in get_data>
>      <dtml-if some_criteria>
>        <dtml-call "REQUEST.set(row_prop,'style1')">
>      <dtml-else>
>        <dtml-call "REQUEST.set(row_prop,'style2')">
>      </dtml-if>
>       <tr>
>       <td class="&dtml-row_prop;"><dtml-var first_col></td>
>       ...
>       <td class="style3"><dtml-var last_col></td>
>       </tr>
>      </dtml-in>

What does get_data do?  The behavior of any dtml-call, dtml-in, dtml-var,
etc. can cause writes based on the method they're calling, iterating over,
rendering, etc.  If your ZODB is growing, something is getting added.

> (2) I get the same behavior when I serve through Apache.
>     (not using ZServer behind Apache, just the generated form
>      served directly through Apache)

Sorry, I don't know the answer to this one... it's evidently a bug in IE
5.5.