Drafter.WidgetValue (drafter v0.3.2)

Reads and writes a widget's primary value by the shape of its state.

There is no per-widget-type table: extract/1 tries the shapes below in order and takes the first one the state satisfies, and update_props/2 maps a new value back onto the props that set it. Drafter.get_widget_value/1, Drafter.set_widget_value/2 and the app loop's own value lookup all come through here, so every path answers alike.

Recognised shapes, in order:

:text — that string. text_input, text_area, label, button, link, loading_indicator, digits, placeholder.
:checked — a boolean. checkbox.
:state holding :on or :off — true for :on. switch.
:selected_index with :options — the id of the option at that index. radio_set, option_list.
:selected_indices with :options — the ids of those options. selection_list.
:expanded — a boolean. collapsible.
:active_tab — the active tab index. tabbed_content.
:selected_rows — that MapSet as a list. data_table.
:selected_nodes — that MapSet as a list. tree.
:value with :min, :max and :step — that number. slider.

Anything else reads as nil.

Summary

Functions

extract(arg1)

The primary value held in state, or nil when no shape matches and for nil.

update_props(arg1, value)

The props that write value into state, or nil when it cannot be written.

Functions

extract(arg1)

@spec extract(map() | struct() | nil) :: term() | nil

The primary value held in state, or nil when no shape matches and for nil.

iex> Drafter.WidgetValue.extract(%{text: "hello"})
"hello"

iex> Drafter.WidgetValue.extract(%{state: :on})
true

iex> Drafter.WidgetValue.extract(%{value: 0.5, min: 0.0, max: 1.0, step: nil})
0.5

iex> Drafter.WidgetValue.extract(%{selected_index: 1, options: [%{id: :a}, %{id: :b}]})
:b

iex> Drafter.WidgetValue.extract(nil)
nil

update_props(arg1, value)

@spec update_props(map() | struct() | nil, term()) :: map() | nil

The props that write value into state, or nil when it cannot be written.

Only three of the shapes extract/1 reads are writable, and the value must match the field's type.

iex> Drafter.WidgetValue.update_props(%{text: "old"}, "new")
%{text: "new"}

iex> Drafter.WidgetValue.update_props(%{value: 0.5, min: 0.0, max: 1.0, step: nil}, 0.9)
%{value: 0.9}

iex> Drafter.WidgetValue.update_props(%{checked: false}, "yes")
nil