JSON Log Line (Single-Line Object) in PY
Match a single-line JSON object — typical of structured logging from services like slog, Bunyan, or Pino.
Try it in the PY tester →Pattern
regexPY
^\{(?:[^{}]|\{[^{}]*\})*\}$Python (re) code
pyPython
import re
pattern = re.compile(r"^\{(?:[^{}]|\{[^{}]*\})*\}$")
input_text = "{\"level\":\"info\",\"msg\":\"started\",\"port\":8080}"
for m in pattern.finditer(input_text):
print(m.group(0))Stdlib `re` module — no third-party dependency. Works on Python 3.6+.
How the pattern works
^\{ anchors to an opening brace at start. (?:[^{}]|\{[^{}]*\})* matches any non-brace chars or one level of nested braces (so `{"a":{"b":1}}` matches but deeper nesting may not). \}$ anchors to the closing brace at end. Quick filter for log-line shape; pair with JSON.parse to validate fully.
Examples
Input
{"level":"info","msg":"started","port":8080}Matches
{"level":"info","msg":"started","port":8080}
Input
{"event":"login","user":{"id":42}}Matches
{"event":"login","user":{"id":42}}
Input
plain text log lineNo match
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