<faq title="PApp Frequently Asked Questions &amp; Tips and Tricks">

<section title="Installation">

<qa q='Why do I need a SYSID?'>

The Agni subsystem in PApp needs unique IDs when creating new objects,
like users.  To enable you to exchange data with other Agni users, these
IDs must not collide with IDs from other system. The easiest way is to use
a unique sysid as part of the object ID. That's the reason why a unique
system ID is important.

</qa>

<qa q='How do I get a SYSID?'>

One way is to use an officially-assigned (thus unique) IPv4
address. Another way is to write an email to sysid@nethype.de, informally
asking for a system ID. If you want, you can provide us with something we
can identify you, so we can keep records of your sysid, but that's not
required.

</qa>

</section>

<section title="Common Mistakes">

<qa q='print "____________"; doesn&apos;t work as expected'>

<c>__"..."</c> marks a translation. If this character pattern shows up
in your source you might get problems. Try to escape it like this
<c>print "___________\_";</c>

</qa>

<qa q='My application is written in language XYZ, but this language is not shown in the language_selector!'>

All languages used in the source must be declared somewhere. If you use
<c>lang="*"</c> then you must declare all possible source languages using the
<c>&lt;language></c> element.

</qa>

<qa q='I try to access %A/%S, a database etc. in a callback, but it does not work.'>

The callback handlers are executed during a very delicate time, before
the actual page gets executed. <c>%S</c> etc. are meaningless during this
time.  If you want to access something you should take a reference to it
and pass it to your callback when you refer() to the callback.

</qa>

</section>

<section title='Features'>

<qa q='How do I get the currently selected language?'>

<c>my $langid = $papp_translator->get_table($PApp::langs)->lang</c>

</qa>

<qa q='How can I quickly get a language selector for all supported languages?'>

<c>&lt;:language_selector $papp_translator:></c>

</qa>

<qa q='How do I include a filename in a surl (e.g. for a nice Save As preset)'>

Use the GET surlstyle together with SURL_SUFFIX, e.g: surl "download",
SURL_STYLE_GET, SURL_SUFFIX, "doc.ps";

</qa>

<qa q='How can I dynamically initialize the default database used by my app?'>

<p>
Use a perl section and call the <c>$ppkg->set_database</c> method:
</p>

<p>
<c>&lt;perl>$ppkg->set_database(new PApp::SQL::Database ...)&lt;/perl></c>
</p>

</qa>

</section>

<section title='Unexplainable Errors'>

<qa q='I get an error like "self is not of type PApp::I18n::Table" while my application gets compiled. What gives?'>

You are calling <c>__</c> or <c>gettext</c> in your module initialization
code. This is too early since there is no user and thus no selected
language at that point.

</qa>

</section>

<section title='Maintainance'>

<qa q='My machine crashed and my application complains about the state database. I am running MySQL'>

This means that a table in your database is corrupt. Because the
state table is the most active one, it is also the most likely to be
corrupted.

You should inqure further about the circumstances that lead to this
corruption and should ask a qualified database engineer to have a look
at the problem and decide about ways to repair it.

However, if it is necessary to bring the system back online immediately
and you don't care about loosing the state information of logged in
users (everybody will have to log in again after this!), you can try the
following this procedure at your own risk: 

WARNING: Never do this with any other table save for the state table!!!

  mysql papp

  ( repair table state; /* You can try this step - it might work without
    having to delete everything */ )

  delete from state;

  quit

</qa>

</section>

</faq>