---
tags:
- System Tasks
alias: user-guide-system-tasks-core
description: "This documentation details a task for processing JSON data using JSONata expressions"
---

# Core

The Core Tasks are comprised of the JSONata Evaluator Task, which is further explained below.

## JSONata Evaluator

The JSONata Evaluator Task allows for complex data manipulation and processing through the use of [JSONata](https://jsonata.org/) expressions. This task is particularly useful for defining and executing expressions that transform or query JSON data structures. To configure an JSONata Evaluator, you need to provide a name and, optionally, a description. Additionally, you can customize its behavior by adjusting the following settings:

* **Auto Refresh** - When enabled, the page will automatically update its data at defined intervals. You can set the specific interval according to your needs. The default setting is `false`.
* **Retrieve Data on Start** - When enabled, the system will fetch and display relevant data as soon as the page loads. The default setting is `true`.
* **Retrieve Data on Changes** - When enabled, the system will update the data displayed whenever there are changes. The default setting is `true`.

![JSONata Evaluator Task](images/uipage_core_jsonata_evaluator.png)

The JSONata Evaluator task includes a Setup tab where you can define the [JSONata](https://jsonata.org/) expression, setting the logic and operations performed by JSONata Evaluator on the input data. The native MES editor will validate your JSONata expression and indicate any errors, as shown belo

=== "Correct JSONata Expression"

    ![JSONata Evaluator Task Output](images/uipage_core_jsonata_evaluator_setup_jsonata.png)

=== "Error in JSONata Expression"

    ![JSONata Evaluator Task Output](images/uipage_core_jsonata_evaluator_setup_error.png)

You will also need to specify the inputs and output, configuring the following fields:

* **Name** - This field must be unique to each input or output.
* **Friendly Name** - You can provide a more user-friendly name for the input or output. This name will be displayed in place of the technical name, making it easier for users to understand its purpose.
* **Type** - Choose the appropriate data type  for the input or output. There are several available types, including Boolean, DataGroup, EntityType, Integer, JSON, StateModel, String, among others.
* **Collection type** - Specify the collection type if the input or output is not a single value. The options are: Array, Map, or None.
* **Default value** - You can define a default value that will be used if no specific value is provided, ensuring the correct execution of the DEE Action.

=== "Inputs"

    ![JSONata Evaluator Task Input](images/uipage_core_jsonata_evaluator_inputs.png)

=== "Outputs"

    ![JSONata Evaluator Task Output](images/uipage_core_jsonata_evaluator_outputs.png)

If the input or output Type is `ReferenceType`, and it is one of the following: `EntityType`, `File`, `Lookup Table`, `Lookup Value`, `Query`, `Role`, `State Model`, or `User`,  you have the option to create a new instance of this value using the **New instance** toggle button.