Combining Multiple Sources

Example

There are 3 data sources connected to supOS, and we need to combine them together for the next step.

{
  "workshop": {
    "furnace1": {
      "temp": 85
    },
    "furnace2": {
      "humidity": 64
    },
    "furnace3": {
      "pressure": 80
    }
  }
}

What Node to be Used?

In this example, we use join node to combine previous messages.

Parameter	Description
Mode	Join mode. • manual: You configure how to merge messages yourself. • auto: Automatically reassemble sequences split by a split node, based on `msg.parts`. • reduce sequence – Runs a JavaScript reduce function across the sequence to produce a single result.
Combine each	Message part you want to combine. Commonly `msg.payload`, but can be others (e.g. `msg.data.value`).
to create	Result type: • a merged Object: Merge all objects into a single object (later keys overwrite same-name keys). • a key/value Object: Use a key property (default `msg.topic`) as the key, and the Combine each property as the value. • an Array: Append each value to an array in order. • a String / a Buffer: Concatenate text or binary data (String can use a separator; Buffer is joined as binary).
Use existing `msg.parts` property	When selected, the node uses the `msg.parts` from previous nodes (usually created by a split node) to determine grouping and when to send the joined output. Fields like `msg.parts.count` and `msg.parts.index` are used.
Send the message → After a number of message parts	Outputs the joined result after receiving the set number of fields.
Send the message → and every subsequent message	When selected, after the initial output, the node outputs an updated result upon new messages arrival.
Send the message → After a timeout following the first message	Optional. Starts a timer when the first message arrives; once the timeout (seconds) is reached, the node outputs whatever has been collected.
Send the message → After a message with the `msg.complete` property set	Outputs the joined result immediately when a message arrives with `msg.complete = true`.
(Advanced) String/Buffer separator	For String output, an optional separator can be set. For Buffer output, data is concatenated directly with no separator.