how to format regex

Thanks for using this module... here's a much needed sample of a regex filter. I've been focusing on getting the module code ready for release, but at this point the documentation is nil.

It matches the feed from Environment Canada for weather.

An item would be formatted as pseudo RSS feed as follows:

<item>
  <title>Current Conditions: Mostly Cloudy, 17.8°C</title>
  <link>http://www.weatheroffice.gc.ca/city/pages/on-143_metric_e.html</link>
  <description><b>Observed at:</b> Toronto Pearson Int'l Airport 4:00 PM EDT Sunday 19 September 2010 <br>
<b>Condition:</b> Mostly Cloudy <br>
<b>Temperature:</b> 17.8°C <br>
<b>Pressure / Tendency:</b> 102.1 kPa falling<br>

<b>Visibility:</b> 24.1 km<br>
<b>Humidity:</b> 52 %<br>
<b>Dewpoint:</b> 7.9°C <br>
<b>Wind:</b> NNE 13 km/h<br>
<b>Air Quality Health Index:</b> 2 </description>
</item>

My Regex match to pull out the parts is like this:

/<item><title>Current (Conditions.+?)<\/title>.*?Humidity:<\/b>.*?(\d+).*?Wind:<\/b> (.+?)<.*/

The Regex replace to format the display is like so:

$1 Hum:$2% Wind:$3

The resulting output of the replacement is:

Conditions: Mostly Cloudy, 17.8°C Hum:52% Wind:NNE 13 km/h

Things to watch out for:

- I'm using the PHP PCRE functions, so it will behave with all the quirks of preg_replace.

- This means the Regex match statement has to match the entire RSS item (that's why I have the ".*" at the end to match everything after wind up to and including ).

- You must have the slash (or other begin / end pair) at the beginning and end of the Regex match. I let you have the choice, just in case you are matching a lot of slashes.

NOTE: I'm assuming you are familiar with regular expressions, if you need more info in that direction please let me know.

Also, if you have any ideas for easier matching of feeds, please share your ideas. I'm hoping to improve this module over time.

First thing, you'll need to be sure the feed is working properly: Just look at example.com/aggregator/sources -- you should see your feed data. If you just set it up, you will need to run cron. Cron should be running on schedule. Whenever cron runs, your twitter feed will be updated. Currently, there is no point in running it more often than 15 minutes, since your feeds won't update any quicker than that.

Next, here's a Regex match expression that will match just the title. The subexpression between the brackets is the text returned. Everything else including the <title> tags will be ignored.

/.+?<title>(.+?)<\/title>.*/

Now, to send this to Twitter, the Regex replace should be:

$1

IE. $1 prints what is matched between the first pair of brackets. $2 would match the second pair and so on.

To have a prefix and suffix, just put that before and after the $1.

Example:

My title: $1, is great

Now that I look at the examples, I'd have to say that regular expressions are a bit confusing, but very powerful. I'll see if I can create a simple "title match" submodule.

Cheers,

CB

Twitter won't accept the anchor tag, so the best thing would be to put the link at the end of the post. The Twitter module can use url shortening service tinyurl and I think it can give you even more choices of you configure the Shorten module (http://drupal.org/project/shorten) as well.

The Regex match should be:

/.+?<title>(.+?)<\/title>.*?<link>(.+?)<\/link>.*/

Then your Regex replace would be:

My title: $1 my link: $2

Of course, it will cut it off at 140 characters, so if the title is too long, the link could be truncated.

This makes me think that I could create a simple version of the filter that used tokens, eg. !title, !link

Just to help me keep track of everything, could you create a new issue in the queue with the message error message above. Since the regex problem is sorted out, I should close this issue.

Also, to help me diagnose the problem, please answer these questions:

1. Which version of Twitter module are you using?

2. Is your Twitter account configured with Oauth? Which version?

3. Have you got all the Twitter submodules enabled?

4. Can you post to Twitter using the twitter_post functionality (eg. When creating a new page or blog post.)

Thanks.