App variables

App variables is a data source available in every app for storing global app state. App variables contains a number of built-in variables and you can also add your own.

These variables can be bound to properties in UI components and action nodes, and referenced in conditions and filters.

Custom app variables

Custom app variables are used to store app state for a given instance of the app. For example, you might need to store a boolean value to track if a component is visible or not, or a datetime value for filtering recently created objects in a list.

App variables are runtime variables, which means that they exist only in the user's browser and are not saved to the database or shared with other users. An app variable will be cleared each time an app is refreshed, unless the Persistence property is populated.

Example: Store the state of a switch to apply a filter

You have a List component bound to a Tasks data source. You would like to only display uncompleted tasks by default, but you would like to add a Switch component to allow a user to also see completed tasks.

To solve this, you can add a custom app variable called Show completed tasks with data type Boolean and bind this variable to the Switch's Value property. Then you can add a Conditional Filter to the List with the Enabled property set to the conditional expression App Variables.Show completed tasks NOT EQUALS true and the Filter property with the filter expression Tasks.Done NOT EQUALS true.

In this case the conditional filter will apply when the app is loaded, and show only uncompleted tasks, since Show completed tasks will not have value. When a user toggles the switch, the conditional filter will be disabled and all tasks will display.

Properties

PropertyDescription

Name

The name used throughout Appfarm Create to refer to this app variable. This name can be changed at any time without technical consequences.

Node Name

The key that is used to store the property in memory.

Data Type

Cardinality

Property Type

An app variable can be either be value or a function.

  • Value: A primitive value that can be read and updated.

Value on Create

Available for Value property type. A default value to set for the property when the app is loaded.

Function

Label True

Label False

Available for Boolean data type. A text label to display when the value is false.

Label Undefined

Available for Boolean data type. A text label to display when the value is undefined (empty) or null.

Persistence

Specify if the value should be stored in the user's browser. There are three options:

  • None: The value will not be stored and will only exist in the current instance of the app. This is the default behavior.

  • Local Storage: The value will be stored in the browser's local storage. It will remain there until the user logs out of the app or the login expires. When the value is stored, it will be available for use the next time the app is loaded. If the user has the app open in multiple tabs, the value will be available to all tabs.

  • Session Storage: The value will be stored in the browser's session storage. It will remain there until the user closes the tab, the user logs out of the app, or the login expires. When the value is stored, it will be available for use the next time the app is loaded.

Description

A longer description of the app variable. For your own reference.

Built-in app variables

The built-in app variables contain standard information about an app while it's in use, such as the active environment or client screen size. Some of these variables are based on built-in enums which can be incorporated into your object classes.

PropertyData typeDescription

Active Environment

Enum

The environment the end-user is using, either Develop, Test, Staging, or Production. This variable can be useful to alter functionality based on if the active environment uses production data (Staging and Production) or not.

Active Language

Enum

Active Theme

Enum

App Time Zone

Enum

The time zone the app is operating in. By default the device time zone is used, but it can be overridden. Calendar data sources are based on this value. Example: Your App has functionality for registering new Events in Norway, with Start and End time. You want to make sure that the start and end time is "Norway time" when your end users are working remote from Asia. The solution is to set App Time Zone fixed for your App (or based on the Event's location). It may be done with a simple Update Object in the On App Load action (setting App Time Zone to Europe/Oslo)

Client IP

String

The end-user's IP address.

Client Screen Size

Enum

The screen size of the end-user's device, either Large, Medium, Small, or Extra Small. This variable can be useful to show/hide UI components based on the available screen real estate.

Device Orientation

Enum

The current orientation of the end-user's device, either Portrait or Landscape.

Device OS

Enum

The end-user's device operating system.

Device OS Version

String

The end-user's device operating system version.

Document Title

String

This variable can be useful to change the page title dynamically. E.g. you may update this property using an Action with an Update Object action node.

Hostname

String

Is Fullscreen

Boolean

If an app has been installed as a Progressive Web App and is running in fullscreen.

Is Main Drawer Open

Boolean

Is Online

Boolean

If the app is currently connected to the server.

Is Unauthenticated

Boolean

If the user is not logged in and using unauthenticated access.

Readable ID

String

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