Python Regular Expression expression excluiding string containing pattern match

Question

I want to create a regular expression to match url links that contain underscore character but I don´t what to match a specific string containing undercore. Bellow are some example with and without matchs indicated:
"site.com/_price_" -> Match
"site.com/price" -> No Match
"site.com/_Desde_" -> No Match - This is important

I have tried the following patterns without success

"\[_](?!\_Desde_)"
"\(?!\_Desde_)\[_]"
"\[\_](^\_Desde\_)"

Answer 1

You may use

_(?!Desde_)[^_]*_

See the regex demo

It matches

• _ - an underscore
• (?!Desde_) - a negative lookahead that fails the match if the _ is followed with Desde_ substring
• [^_]* - 0+ chars other than _
• _ - an underscore.