@sammachin/node-red-lookup 1.0.0
Node-RED node that maps the value of one message field to another using a lookup table, with a configurable default for no match
@sammachin/node-red-lookup
A single Node-RED node that maps the value of one message field to another using a lookup table.
You choose a source field to read and a target field to write (they can
be the same field), give it a list of from → to pairs, and decide what happens
when a value isn't in the table.
Example
Source msg.payload.from, target msg.payload.to, with pairs:
123 → 456
+441234 → +445678
An incoming msg.payload.from = "123" produces msg.payload.to = "456".
Configuration
| Field | Description |
|---|---|
| Source | The field to read. A msg property (default payload), or flow / global context. |
| Target | The field to write on a match. Same choices as source; set it equal to the source to rewrite in place. |
| Pairs | The lookup table. The left side (from) is matched by value; the right side (to) is a typed input, so it can be a string, number, boolean, JSON, a message / context property, or a JSONata expression. |
| No match | What to do when the source value isn't in the table (see below). |
Matching
Matching is by value as a string, so the number 123 and the string "123"
both match a pair keyed 123. A missing source field (undefined) never
matches. If two rows share the same from value, the first one wins.
No match
- Pass through unchanged — the target is left alone and the message is sent on.
- Set a default value — the target is set to a fixed value, then sent on.
- Send to 2nd output — the node grows a second output; matched messages leave the first output, unmatched ones leave the second, so you can handle them separately.
Develop
npm install
npm test
The node lives in src/nodes/lookup.js (runtime) and src/nodes/lookup.html
(editor). Tests use node-red-node-test-helper.
Licence
MIT
