7 Text Messages with Message Catalogs

In many web applications, you will find that you need to display text messages to the web user, such as error messages, alert messages, success messages, and so forth. Yet you do not wish to type these messages directly into your STML templates; what if you use them in many places on your Web site, and then you have to change the text of a message? You do not want to have to hand-edit each STML document to make the change.

STML provides a nice way to manage text messages and avoid hard-coding them into your STML documents: message catalogs. An STML message catalog acts somewhat like a Python dictionary: you give it a key, which is a string, and the mesage catalog looks up the message for that key. Unlike a dictionary, an STML message catalog does not raise an error if it cannot find a message under the key you request; instead, the message catalog returns an empty string "".

Unlike a dictionary, a message catalog is not an object which you work with directly. Instead, you use the <:msg:> tag to access messages in the catalog.

There are two kinds of message catalogs in STML:

Regular, or ``simple'', catalogs: Dictionary-like message catalogs. Each message ``name'' is like a dictionary key, with a single message stored for each key.
Multi-lingual, or ``complex'', catalogs:: Like a simple catalog, except that each message key stores multiple messages, one message for each language in the catalog. (Currently supported languages are 'esp' (Spanish), 'por' (Portuguese), and 'eng' (English).

The following sections explain the three tags which provide message catalog features.

Subsections