find word only in single braces using regex in python

Question

I have a string like

text= '{username} joined {servername} {{anytext {find} this {and} this also}} '

and a simple regex code

print(re.findall('{([^{}]*)}', text))

#output
['username', 'servername', 'anytext']

Where anytext is inside double braces but it is also validating by the regex. I mean, the regex should only find word in single braces and ignore double braces.

Please help me to do this happen.

Answer 1

Assuming you only expect either {...} or {{...}} we can use the following re.findall trick:

text = '{username} joined {servername} {{anytext}}'
matches = [x for x in re.findall(r'\{\{.*?\}\}|\{(.*?)\}', text) if x]
print(matches)  # ['username', 'servername']

The trick here is to match {{...}} first in the alternation followed by {...}, while only capturing the second single bracket version. We filter off the empty matches, leaving behind the matches we want.