---
title: JSONata Processor
slug: litmusedge/jsonata-processor
docTags: 
createdAt: 2025-03-20T15:37:23.156Z
---

The JSONata Processor transforms incoming JSON payloads using a JSONata expression you define, letting you reshape, filter, or combine fields from one or more inputs without writing custom code.

## Why use the JSONata Processor

Use this processor when you need to query or restructure JSON data with JSONata's expression language, for example, extracting and renaming fields from a device payload, or combining fields from multiple inputs into a new shape.

## How it works

Write your JSONata expression in the Code Editor, which supports syntax highlighting and real-time validation.

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From the editor, you can also access:

- **Fullscreen** to show the Code Editor in full-screen mode.

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- **Playground** to test, write, and validate your expression in real time before deploying it.

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- **Validate** to check your expression's syntax.

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### Event wires versus value wires

The wire type you connect determines how your expression addresses the input:

- With an **Event** wire you reference incoming fields directly by name with no wire-name prefix. You can connect multiple event-wire inputs to one JSONata processor but each is processed independently and generates its own output payload.
- With a **Value** wire every field is prefixed with its wire name. The processor waits until every connected value-wire input has produced a payload before it produces output, holding earlier payloads in memory until the later ones arrive.

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## Examples

Using Event wires as input:

- When using the Event wire type, there is no need to specify the wire name when defining the fields in the JSONata expression.
- You can define multiple inputs into a single JSONata process. However, each input is considered as it’s own process flow and generates a new payload.

Input payload:

```json
{
  "datatype": "float64",
  "description": "",
  "deviceID": "75F601CA-0F7A-4C26-90F0-470E2424BAC1",
  "deviceName": "Gen",
  "metadata": {},
  "registerId": "D5DCF52F-342B-4211-8F4F-B92E4406BC4C",
  "success": true,
  "tagName": "tag1",
  "timestamp": 1739558895577,
  "value": 0.38164469548275337
}
```

JSONata expression. In this example, you simply define the field name from the input in the expression:

```json
{ 
  "metric": $substring(tagName,3), 
  "value": value, 
  "date": $fromMillis(timestamp, '[M01]/[D01]/[Y0001] [h#1]:[m01][P]') 
}
```

Output payload:

```json
{
  "date":"02/14/2025 6:51pm",
  "metric":"1",
  "value":0.38164469548275337
}
```

Using Value wires as input:

- When using the Value wire type, every input field must be a prefix wire name.
- The JSONata processor will not produce a payload until all input payloads are present. For example, the payload from input 1 is stored in memory until input 2 produces a payload.

Input payload 1:

```json
// wirename = Input_1
{ 
  "datatype":"float64", 
  "description":"current metric",
  "deviceID":"75F601CA-0F7A-4C26-90F0-470E2424BAC1",
  "deviceName":"Gen",
  "metadata":{},
  "registerId":"D5DCF52F-342B-4211-8F4F-B92E4406BC4C",
  "success":true,
  "tagName":"tag1",
  "timestamp":1739558895577,
  "value":0.38164469548275337 
}
```

Input payload 2:

```json
//wirename = Input_2
{ 
  "datatype":"float64",
  "description":"temp metric",
  "deviceID":"75F601CA-0F7A-4C26-90F0-470E2424BAC1",
  "deviceName":"Gen",
  "metadata":{},
  "registerId":"D5DCF52F-342B-4211-8F4F-B92E4406BC4C",
  "success":true,
  "tagName":"tag2",
  "timestamp":1739558895577,
  "value":-1.8813568907902232 
}
```

Output payload:

```json
{ 
  "metric_1": tsg1, 
  "metric_2": tag2, 
  "value_1": 0.38164469548275337, 
  value_2": -1.8813568907902232, 
  "date": "date":"02/14/2025 6:51pm" 
}
```