Custom Reports Using Eguile

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.

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 the "From a user account" section of the Custom Reports page). The easiest way is to put all the files for a report into your .gnucash folder, and then add a line to .gnucash/config.user like this:

(load-from-path "/path/to/my/.gnucash/report.scm")  

If .gnucash/config.user does not already exist, just create it and add the new line.

For example, on a Linux system, for a user called 'chris', the Tax Invoice report can be installed by:

1. Downloading taxinvoice.scm and taxinvoice.eguile.scm, and putting them into the /home/chris/.gnucash/ folder.
2. Adding this line to /home/chris/.gnucash/config.user:

(load-from-path "/home/chris/.gnucash/taxinvoice.scm")

Restart GnuCash, and 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 (as a string which is passed back to the report-displaying part of GnuCash).

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:

 <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

Report file:	taxinvoice.scm
Template file:	taxinvoice-eguile.scm
CSS file:	none
Sample output:	PDF
Author:	ChrisDennis
Version:	0.01
Last update:	June 2009

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

Report file:	balsheet-eg.scm
Template file:	balsheet-eg.eguile.scm
CSS file:	balsheet-eg.css
Sample output:	PDF
Author:	ChrisDennis
Version:	0.01
Last update:	June 2009