Oracle - Search for text - Retrieve snippet of result - regex

Question

I'm currently building a simple search page in Node JS Express and Oracle.
I'd like to show the user a snippet of the matching text (first instance would do) to add a bit context of what the SQL found.
Example:
Search term: 'fish'
Results: Henry really likes going fishing, and once he caug ...
I'm not sure the best way to approach this - I could retrieve the whole block of text and do it in Node JS, but I don't really like the idea of dragging the whole text across to the app, just to get a snippet.
I've been thinking that REGEXP_SUBSTR could be way to do it... But I'm not sure whether I could use a regular expression to retrieve x amount of characters before and after the matching word.
Have I got the right idea or am I going about it in the wrong way?
Thanks
SELECT text
, REGEXP_SUBSTR(LOWER(text), LOWER('fish')) AS potential_snippet
FROM table
WHERE LOWER(text) LIKE LOWER('%fish%');

Answer 1

Try this:
select text
, SUBSTR( TEXT, INSTR(LOWER(TEXT),'fish', 1)-50,100 )
FROM test
WHERE INSTR(LOWER(text),'fish', 1)<>0;
Play with the position and length numbers(50 and 100 in my example) to limit the length of the string.

Answer 2

If you need to extract some context with the help of JavaScript, you can use limiting quantifiers in a regex:
/\b.{0,15}fish.{0,15}\b/i
See demo
Here,
\b - matches at the word boundary (so that the context contains only whole words)
.{0,15} - any characters other than a newline (replace with [\s\S] or [^] if you need to include newlines)
fish - the keyword
The /i modifier enables case-insensitive search.
If you need a dynamic regex creation, use a constructor notation:
RegExp("\\b.{0,15}" + keyword + ".{0,15}\\b", "i");
Also, if you need to find multiple matches, use g modifier alongside the i.