How to use regular expressions within QGIS Actions

Question

I have stored html links in a column of a postgis layer. There are a few entries which have multiple links stored in one cell (blank separated). I have to use the firefox.exe to open the links in multiple tabs. This doesn't work with Open type,

I can open these links with:

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" [% "link" %] 

An entry of link looks like:

file:///H:/going/goingfurther_01_page.html

Now I want to use the same column to open the link in this way:

file:///H:/going/page.html

I tried:

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" [% regexp_replace("link",'goingfurther_[0-9][0-9]_' ,'') %]

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" regexp_replace([% "link" %],'goingfurther_[0-9][0-9]_' ,'')

But QGIS can't open this. The first replace expression works with the field calculator.

Answer 1

Into the blue untested: Following the instruction in the qgis tutorial it seems, that the call Open file_location/file.type, to start an application like a browser, is connected with the default settings for the mimetype type in your OS. May Open is a wrapper around os.startfile.. for example...

One way to solve the problem could be, to register the application firefox to the content of to text/html.

A second opportunity, you could follow, is shown in paragraph 6.4.5 of the same qgis tutorial. The action statement (here a call to show the internal web componenet QWebView):

from PyQt4.QtCore import QUrl; \
from PyQt4.QtWebKit import QWebView; \
myWV = QWebView(None); \
myWV.load(QUrl('http://wikipedia.org/wiki/[% "name" %]')); \
myWV.show()

could be adopted in a pythonish way to start the firefox application.

import os; \
app  = "'C:\\Program Files (x86)\\Mozilla Firefox\firefox.exe' "; \
file = [% regexp_replace("link",'goingfurther_[0-9][0-9]_' ,'') %]; \
os.system(app+" "+file);

Or

import subprocess; \
subprocess.call([app, file]); \

if you have problems with the spaces and quotes.

Remarks:

1. I add some line breaks to the action code. The sign \ at the end of each line indicates, that the code has to be written in one line in the action field.

2. The QGIS Application / Map setup works a little bit like a dynamic web application with GIS capabilities. This could be done in a more transparent way but with much more effort.