Opus 2.27 Publisher's Manual  Product Overview  Installation and Set Up  Customising a Paper   Templates  Using Datacards  Using Objects  Author Maintenance  Activity Logging  Technical Issues  Appendices

Note that text shown in this style documents a feature which isn't in the current release but will be in the next release and text shown thus indicates a feature which is being removed in the next release.

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Using Objects

Basics

An object in Opus consists of three elements: its name, which can be up to twenty characters, its description, which describes what it is, and its content, which can be up to 64Kbytes of text. This text can include HTML but not Opus mark up.

You can insert the content of an object into a web page in two ways:

• In articles using a tag: {object:name}
• In templates using an opusfield: <opusfield name="object" object="name"/>

There are three sorts of objects: system, user and paper.

System Objects

System objects have names beginning with a "$" and let you insert changing system information from Opus in your web pages. The following system objects are available:

Name	Contents	Example
$time-12hm	Time now in 12 hour HH:MM format	1:45 pm
$time-12hms	Time now in 12 hour HH:MM:SS format	1:45:11 am
$time-24hm	Time now in 24 hour HH:MM format	13:45
$time-24hms	Time now in 24 hour HH:MM:SS format	13:45:11
$date-iso	Today's date in ISO format (YYYY-MM-DD)	2002-07-31
$date-dmy	Today's date in DD/MM/YY format	31/07/02
$date-mdy	Today's date in MM/DD/YY format	07/31/02
$date-long	Today's date in long format	31st July, 2002
$date-arpa	Date/time in RFC922 (APRA) format	Sat, 07 Sep 2002 00:00:01 GMT
$day-short	Day in three letter short format	Fri
$day-long	Day in long format	Friday
$month	Month in text format	December
$year	Year	2002
$opus-release	Current Opus release	2.11

 

User Objects

Updating Objects From Within Opus

You can update objects from within Opus using the "Browse objects" option in the author menu.

Updating Objects From Outside Opus

Assuming that you have access to the MySQL server and the right permissions you can update an object from outside Opus using the shell script ./bin/opus_object.sh. This script is a pipe which takes five parameters. You send the content you want to insert to:

| opus_object host user pass database name [desc [paper]]

where host is the host where the MySQL server lives, user and pass are the username and password for accessing the database, database is the Opus MySQL database you want to update, and name is the name of the object you want to update. You can optionally pass a description in desc and, if you've got more than one paper, you need to identify that by passing the papercode in paper (assumed to be 1 if not passed).

Using PHP in User Objects

Is is possible to embed PHP code within an object. This is a powerful and potentially dangerous feature in the wrong hands so only the publisher can create such objects. An object which uses PHP must begin <?php and end ?>. When the code is run it must set a variable $contents which contains the contents of the object which are to be displayed.

Your web browser isn't the ideal PHP programming editor so it's perfectly possible to include code from a file. We have an object camweather which we use in the Milton site which displays the current weather in a text box. The PHP code for this is in a file weather.inc and the object contents are simply:

<?php
include("../web/weather.inc");
?>

Paper Objects

If you want to go beyond the embedding of PHP into a user object you can use a paper object. You would use this if you need to do something complicated in PHP. You create a file objects.inc in your paper's directory.

This should include within it a function paper_object() which takes a single parameter, the name of an object, and returns the value of the object.

Your code can do what it likes, although for safety you should precede any functions you create with a suitable prefix so you don't get function name clashes with Opus - a good choice would be local_.

Having created the object in your function paper_object() you must also define in it Opus. You can do this using the "Browse objects" option in the author menu.

You can now use the object in your templates or articles, prefixed by "#". Here's a simple example of an objects.inc file:

<?php
function paper_object($name)
{
    switch { $name }
    {
        case "test":
            return "Hello world";
        default:
            return "[Unknown object ".$name."]";
    } 
}
?>

You can then refer to this in an article as {object:#test} and will result in the text "Hello world" appearing in the article at the position when it's published.

Note the error message returned if the object name isn't recognised: if you use this exact format then when checking an article an author has written Opus can spot invalid objects.

Why Are Objects Useful?

System objects are useful for inserting information into web pages which changes often, like today's date and the usefulness of paper objects is only limited by your imagination.

User objects are useful for two things: as a shorthand for putting long bits of text into an article which occurs on many pages (but do think about doing this from the template, possibly using an <opustest> ... </opustest> portion of the template). They are also useful for other information which changes often. For example suppose you change the sales executive responsible for modem sales fairly often but you need to refer to that sales executive by name in every web page (i.e. article) about a modem.. Then you can create an object named modem-salesexec and in all your articles about modems you would put:

Contact {object:modem-salesexec} for more information.

And then by changing the contents of the modem-salesexec object all the pages referring to it would change automatically.

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