---
title: Properties and Expression Builder
description: Learn about Properties and Expression Builder functionalities
documentId: ipaas-legacy-expression-builder
locale: en-US
---

## Overview

The **Properties** ![list icon](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_icon_2c777edb35.png) functionality can be accessed from some fields in the configuration forms of specific *steps* in **Diagram** type integration flows.

It simplifies data and configuration manipulation in the integration flow, making processes more dynamic and customizable.
It allows you to:

- Select previously registered [variables](#selecting-variables).

- Select input or output [payloads](#selecting-payloads-from-previous-steps) from the following previous *steps*:
  
   - REST triggers
   - REST API connectors
   - Technical connectors (databases, cloud providers, and ERP systems)
   - JSON Transformation

- Create custom expressions using the [Expression Builder](#creating-an-expression-in-expression-builder).

## Steps with fields configurable via Properties

* **Trigger**
  * Scheduler
    * **Cron Expression**

>![properties-scheduler.png](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_scheduler_a29aab88ba.png)

* **General tools**
  * For Each
    * **Variable List**

>![properties-for-each.png](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_for_each_18956e0a6b.png)

  * On Exception
    * **Retry Interval (ms)**
    * **Retry Quantity**

>![properties-onexception.png](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_onexception_7c198c5ab1.png)

* **Connectors**
  * REST API
    * **URL**
    * **Request Timeout**

>![properties-rest-api.png](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_rest_api_e54da3415e.png)

  * Technical
    * **Timeout**
    * Available in the left panel, next to **INSTRUCTION**

>![properties-tech-connectors.png](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_tech_connectors_de9e9a3395.png)

## Selecting variables

The animation below shows the configuration form of a REST API connector, in which the **URL** field was filled with a previously registered variable.

>![properties-env-var.gif](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_env_var_2809f047e5.gif)

<Callout type="note" title="NOTE">
See how to register [environment variables](/docs/integrations/ipaas-legacy-variables).
</Callout>

## Selecting payloads from previous steps

The animation below shows the configuration form of the For Each tool, in which the **Variable List** field was filled with the output *payload* from a previous *step*.

>![properties-payload.gif](https://creative-ball-51b3fc85c0.media.strapiapp.com/properties_payload_e2a8abf55a.gif)

<Callout type="note" title="NOTE">
Read more about the [For Each](/docs/integrations/ipaas-legacy-for-each) tool.
</Callout>

## Creating an expression in Expression Builder

When you click the ![expression icon](https://creative-ball-51b3fc85c0.media.strapiapp.com/expression_builder_icon_51852bbe38.png) icon in the upper right corner of the **Properties** modal, you will see the **Expression Builder** screen.

This component allows you to create expressions with parameters and variables through functions and conditions available within it.
Thus, you can adjust the expression according to your needs.

The image below presents as an example a *header* from a REST API connector, whose value was configured in the *Expression Builder* using an environment variable.

>![expression-builder-example.png](https://creative-ball-51b3fc85c0.media.strapiapp.com/expression_builder_example_8d86c75bfe.png)

The **Expression Builder** screen contains the following sections:

* **Properties**: shows data from previous *steps* and registered environment variables.
You can filter attributes using the search field at the top of the section and clicking ![magnifying glass icon](https://creative-ball-51b3fc85c0.media.strapiapp.com/search_icon_0b61e0a406.png).
You can select more than one attribute.
When you select it, the attribute appears in the *Expression* field.
* **Expression**: field to insert input attributes or create an expression by clicking the ![fx button](https://creative-ball-51b3fc85c0.media.strapiapp.com/function_icon_50715399e6.png) button on the right.
Only the Concat function is available to create the expression.

<Callout type="important" title="IMPORTANT">
When selecting two or more attributes in the **Properties** field, creating an expression will be mandatory.
</Callout>

<Callout type="note" title="NOTE">
See how to build an expression using the [Concat Function](/docs/integrations/ipaas-legacy-concat).
</Callout>

To save the information, click **SAVE**.
To close the screen without saving changes, click **CANCEL**.