node-red-contrib-mapper

A [Node-RED] node that maps the contents of a message property from one value to another, supporting multiple mapped values, context references, JSONata expressions, environment variables, and regular expressions.

The message property is compared against each configured rule: you can match several values (comma-separated) or apply regex patterns (by selecting type regex). If there’s a match, it changes to the specified replacement value.

By default, the msg.payload is the property that is operated on, but this can be changed to any other property, such as msg.topic.

If the message does not match any of the configured mappings, it can either be ignored or passed through unmodified.

Install

Run the following command in the root directory of your Node-RED install

npm install @patricktobias86/node-red-contrib-mapper

Usage Examples

✅ Multiple values in one rule
You can map several values to a single replacement by entering them comma-separated, for example:

• Search: apple, banana, orange → Replace: fruit

✅ Regex matching
You can use regex patterns by selecting the regex type for the search field:

• Search: ^error_\\d+ (type: regex) → Replace: general_error

✅ Combining rules
You can combine plain and regex rules:

• Rule 1: yes, y, true → confirmed
• Rule 2: ^no_.* (type: regex) → rejected

✅ Supported Types
Each rule supports flexible types for both search and replace fields:

• msg, flow, global: Reference properties from the message or context.
• str, num, bool: Use raw string, number, or boolean values.
• regex: Use regular expressions (in search or replace).
• jsonata: Evaluate an expression using the msg context.
• env: Pull from environment variables.

You can mix and match these types per rule.

💡 Tip: For regex, write one pattern per rule and select the regex type.