Stripping HTML tags in PostgreSQL

Question

How would you strip HTML tags in PostgreSQL such that the data inside the tags is preserved?

I found some solutions by googling it but they were striping the text be

Answer 1

The choice is not limited to doing it server-side with a weak parser based on inadequate regexps or doing it client-side with a robust parser. It could be implemented server-side with a robust parser, too.

Here's an example in PL/PerlU that takes advantage of the CPAN's HTML modules.

CREATE FUNCTION extract_contents_from_html(text) returns text AS $$
  use HTML::TreeBuilder;
  use HTML::FormatText;
  my $tree = HTML::TreeBuilder->new;
  $tree->parse_content(shift);
  my $formatter = HTML::FormatText->new(leftmargin=>0, rightmargin=>78);
  $text = $formatter->format($tree);
$$ LANGUAGE plperlu;

Demo:

select extract_contents_from_html('Hi there!
How are you?') ;

Output:

     extract_contents_from_html 
    ----------------------------
     Hi there!
     How are you?

One needs to be aware of the caveats that come with untrusted languages, though.