Difference between revisions of "Custom Reports Using Eguile"

Revision as of 10:37, 2 July 2009

What is eguile?

eguile is a way of processing a template file to create a guile script.

More specifically, within GnuCash, guile is used to combine HTML and guile code to create a report, such as an invoice or balance sheet.

The GnuCash version of eguile is eguile-gnc.scm, written in early 2009 by Chris Dennis, and based on Neale Pickett's eguile.scm.

For example,

<source lang="html4strict">
<h3><?scm:d coyname ?></h3>
<h2><?scm:d reportname ?> as at <?scm:d (gnc-print-date opt-date-tp) ?></h2>
</source>

could become

<source lang="scheme">
(display "<h3>")(display "Acme Tools Ltd.")(display "</h3>
<h2>)(display "Balance Sheet")(display " as at ")
(display "05/04/2009")(display "<h2">)
</source>

which is then evaluated as guile code to create the text of the report.

...the rest of this page will be here very soon

see [1] for more information.

How to install an eguile report

To try out eguile-based reports, you first need to download eguile-gnc.scm and put it into the report folder. On my system -- Ubuntu -- that's /usr/share/gnucash/guile-modules/gnucash/report/eguile-gnc.scm. In general, it should go into the same folder as files such as fancy-invoice.scm.

Note: GnuCash 2.3/2.4 already includes eguile-gnc.scm.

Install the report and its associated files in the usual way (see Custom Reports). Put taxinvoice.eguile.scm in the same place, but note that it's location is an option in taxinvoice.scm -- it can be changed either in the source code, or from the report's option menu.

The report should then show up somewhere in the reports menu, depending on the menu-path option in the report. The Tax Invoice and Balance Sheet reports (see below) put themselves into the Reports/Business sub-menu.

How to create an eguile report

...

eguile syntax

Within what is otherwise an HTML source file, Guile/Scheme code is wrapped in '<?scm ... ?>' (whitespace is required after '<?scm' and before '?>')

'<?scm ... ?>' pairs can NOT be nested.

The optional :d modifier (i.e. '<?scm:d' ) is just a shortcut for '(display ... )', so '<?scm:d x ?>' is the same as '<?scm (display x) ?>'

Note that s-expressions can be spread across more than one '<?scm ... ?>', for example:

<?scm (if (> x 3) (begin ?>Bigger<?scm ) (begin ?>Smaller<?scm )) ?>

Each chunk of text outside a '<?scm ... ?>' pair ends up wrapped in a (display ... ), after having had double quotes etc. escaped.

The processing happens in two passes. Initially the input file is converted to a Guile script, and then that script is evaluated to produce the final result. For example, if the input file contained these lines:

 <h1 align="center">Invoice <?scm:d invoiceid ?></h1>
 <?scm (for-each (lambda (entry) ?>
   <p>Date: <?scm:d (entry date) ?>, description: <?scm:d (entry desc) ?>
 <?scm ) entries) ?>

the resulting script would look like:

 (display "<h1 align=\"center\">Invoice ")(display invoiceid)(display "</h1>")
 (for-each (lambda (entry)
   (display "<p>Date: ")(display (entry date))
   (display ", description: ")(display (entry desc))
 ) entries)

and the final result might be this string:

 "<h1 align=\"center\">Invoice 002345</h1>
   <p>Date: 04/03/2009, description: Widgets
   <p>Date: 05/03/2009, description: Modified widgets"

...

Internationalisation

Always use _ rather than N_ in the template file. N_ can be used for report option names, help text, and default values.

Available Reports

The following eguile-based reports are available. More will be contributed soon (hopefully).

Tax Invoice

Notes:

• taxinvoice.scm includes code to display individual taxes on a per-entry basis, i.e. on each line of the invoice. This relies on a fix to the Swig encoding that is currently in the pipeline as bug #573645, but it includes a work-around so that it simply misses out the extra columns if that fix hasn't been applied. This bug has been fixed in 2.3/2.4.

Balance Sheet