regex

Overview

The regex node applies regular expressions to message string values. Supports pattern matching, data extraction with capture groups, find-and-replace, string splitting, and boolean testing. Powerful for parsing log files, validating input formats, and transforming structured text data.

Properties

Operation Modes

match: returns full matches
extract: returns capture groups

Pattern: (\d+)\.(\d+)
Input:   "temp=24.5"
Extract: ["24", "5"]

Pattern: \s+
Replace: "_"
Input:   "sensor  raw data"
Output:  "sensor_raw_data"

split: "a,b;c" → ["a","b","c"]
  Pattern: [,;]

test: returns true/false
  Pattern: ^\d+$
  "123" → true
  "abc" → false

Example: Extract Numbers from Log Lines

Parse structured log output from serial devices to extract numeric readings.

// Regex node configuration
{
  "pattern": "T=(\d+\.\d+)\sH=(\d+\.\d+)\sP=(\d+\.\d+)",
  "operation": "extract",
  "property": "payload",
  "ignoreCase": false,
  "multiline": false
}

// Input (serial log line):
// "2024-01-25 14:30:22 T=24.50 H=62.30 P=1013.25"

// Output (extracted capture groups):
{
  "payload": ["24.50", "62.30", "1013.25"]
}

// Follow with a change node to structure:
{
  "temperature": 24.50,
  "humidity": 62.30,
  "pressure": 1013.25
}

Example: Validate Email Addresses

Test incoming form data for valid email format before processing.

// Regex node configuration
{
  "pattern": "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$",
  "operation": "test",
  "property": "payload.email",
  "ignoreCase": true
}

// Flow: http-in → regex (test) → switch → process / reject

// Input:
{ "payload": { "email": "user@example.com" } }
// Output: { "payload": true }  → switch routes to process

// Input:
{ "payload": { "email": "not-an-email" } }
// Output: { "payload": false } → switch routes to reject

Example: Clean and Transform Serial Data

Strip control characters and reformat raw serial input.

// Regex node: strip control characters
{
  "pattern": "[\x00-\x1F\x7F]",
  "operation": "replace",
  "replacement": "",
  "property": "payload",
  "global": true
}

// Input:  "\r\nSENSOR:OK:24.5:62\r\n"
// Output: "SENSOR:OK:24.5:62"

// Chain a split regex to tokenize:
{ "pattern": ":", "operation": "split" }
// Result: ["SENSOR", "OK", "24.5", "62"]

Common Use Cases