Writing Dynamic UI

Often is the case that the UI is not just a form to collect data and that’s all about it. In fact, we want sometimes hide/show some widgets, reset their values, validate their contents and these sort of things.

Teabox offers a simple signalling mechanism. It more works like old-school Web CGI script.

Module State

Your Bash (or Python or whatever) script can have its state during the session. If you activated a form in Teabox, it will create a session for you, which essentially is a very simple in-memory key/value storage when Teabox is running. Typical use-cases for the session are:

• Maintain module state

• Exchange data between separate scripts

• Exchange data between modules

You can refer to the API List description for details how to access it.

Data Visibility

Each key is actually named with the prefix of the module name. If the name is “my_module”, then a key e.g. “foo” in reality will be stored as “my_module.foo”. So there is no way to access from the other module, because then request key will be prefixed with that module and so on.

Therefore all keys are always private to a module.

Public Visibility

However, if there is a need to share data across the modules (not recommended due to “ad-hoc” nature of this approach), this is still possible to declare a key as public.

To declare a key as public, it needs to be prefixed with a colon “:”, like so:

session::set{:name}"John Smith"

In this case key “:name” will not be prefixed and in this way can be accessed from anywhere, e.g. from another module within the same runtime session of Teabox.

Signal Slots

Signal slots allows to perform an action when an event occurs. There are following events supported:

• Widget was selected

• Widget was de-selected

• Widget was changed (its value)

Each of these widget states can trigger an action that calls any script within the module directory, where the parameters are defined in “init.conf” file of the module itself.

Example:

args:
  - type: toggle
    name: --
    attributes:
      - view-only
    label: "Show other widget"
    signals:
      selected: target.sh --show-optional-widgets
      deselected: target.sh --hide-optional-widgets

The script “target.sh” then should implement all the logic and call any of Teabox’s API List to do something, for example hide or show a widget, or fill it with some value etc.