defmodule LiveSelect do
@moduledoc ~S"""
Dynamic search and selection component for LiveView.
The `LiveSelect` input is rendered by calling the `live_select/3` function and passing it a form and the name of the input.
LiveSelect creates a text input field in which the user can type text, and a hidden input field that will contain the value of the selected option.
As the text changes, LiveSelect will render a dropdown below the text input
containing the matching options, which the user can then select.
Selection can happen either using the keyboard, by navigating the options with the arrow keys and then pressing enter, or by
clicking an option with the mouse.
Whenever an option is selected, `LiveSelect` will trigger a standard `phx-change` event in the form. See the "Examples" section
below for details on how to handle the event.
After an option has been selected, the selection can be undone by clicking on text field.
## Reacting to user's input
Whenever the user types something in the text input, LiveSelect sends a `t:LiveSelect.ChangeMsg.t/0` message to your LiveView.
The message has a `text` property containing the current text entered by the user, and a `field` property with the name of the LiveSelect input field.
The LiveView's job is to [`handle_info/2`](`c:Phoenix.LiveView.handle_info/2`) the message and then call `update_options/2`
to update the dropdown's content with the new set of selectable options. See the "Examples" section below for details.
## Styling
You can use the `style` option in `live_select/3` to control which style will be used by default. Currently supported values are
`:daisyui` (default) or `:none` (no predefined styles). Support for vanilla Tailwind styles is planned for the future. LiveSelect can style the following elements:
1. The outer container of the component
2. The text field
3. The text field when an option has been selected
4. The dropdown with the options
5. The active option the user navigated to using the arrow keys
For each of these components there is a `{component}_class` and for some a `{component}_extra_class` option, which can be used
to either override or extend the default CSS classes for the component. You can't use both options together: use `{component}_class`
to completely override the default classes, or use `{component}_extra_class` to extend the default.
The following table shows the default styles for each component and the options you can use to adjust its CSS classes.
|Component|Default daisyUI classes|class override option|class extend option|
|--|--|--|--|
|*outer container*|"dropdown"|`container_class`|`container_extra_class`|
|*text field*|"input input-bordered"|`text_input_class`|`text_input_extra_class`|
|*text field selected*|"input-primary text-primary"|`text_input_selected_class`| |
|*dropdown*|"dropdown-content menu menu-compact shadow rounded-box"|`dropdown_class`|`dropdown_extra_class`|
|*active option*|"active"|`active_option_class`| |
For example, if you want to show a full-width LiveSelect component with a secondary color for the dropdown background
and active options with a warning background, you can do this:
```
live_select(form, field,
container_extra_class: "w-full",
text_input_extra_class: "w-full",
dropdown_extra_class: "w-full bg-secondary",
active_option_class: "bg-warning"
)
```
Result:
## Examples
Here's an example that describes all the moving parts in detail. The user can search for cities.
The LiveSelect main form input is called `city_search`.
When a city is selected, the coordinates of that city will be the value of the form input.
Then name of the selected city is available in the text input field named `city_search_text_input`.
Template:
```
<.form for={:my_form} let={f} phx-change="change">
<%= live_select f, :city_search %>
</.form>
```
LiveView:
```
import LiveSelect
@impl true
def handle_info(%LiveSelect.ChangeMsg{} = change_msg, socket) do
cities = City.search(change_msg.text)
# cities could be:
# [ {"city name 1", [lat_1, long_1]}, {"city name 2", [lat_2, long_2]}, ... ]
#
# but it could also be (no coordinates in this case):
# [ "city name 1", "city name 2", ... ]
#
# or:
# [ [label: "city name 1", value: [lat_1, long_1]], [label: "city name 2", value: [lat_2, long_2]], ... ]
#
# or even:
# ["city name 1": [lat_1, long_1], "city name 2": [lat_2, long_2]]
update_options(change_msg, cities)
{:noreply, socket}
end
@impl true
def handle_event(
"change",
%{"my_form" => %{"city_search_text_input" => city_name, "city_search" => city_coords}},
socket
) do
IO.puts("You selected city #{city_name} located at: #{city_coords}")
{:noreply, socket}
end
```
### Multiple LiveSelect inputs in the same LiveView
If you have multiple LiveSelect inputs in the same LiveView, you can distinguish them based on the input field.
For example:
Template:
```
<.form for={:my_form} let={f} phx-change="change">
<%= live_select f, :city_search %>
<%= live_select f, :album_search %>
</.form>
```
LiveView:
```
@impl true
def handle_info(%LiveSelect.ChangeMsg{} = change_msg, socket) do
options =
case change_msg.field do
:city_search -> City.search(change_msg.text)
:album_search -> Album.search(change_msg.text)
end
update_options(change_msg, options)
{:noreply, socket}
end
```
"""
import Phoenix.LiveView.Helpers
alias LiveSelect.ChangeMsg
@doc ~S"""
Renders a `LiveSelect` input in a `form` with a given `field` name.
LiveSelect renders a hidden input with name `field` which contains the selected option.
The visible text input field will have the name `#{field}_text_input`.
**Opts:**
* `disabled` - set this to a truthy value to disable the input field
* `placeholder` - placeholder text for the input field
* `debounce` - number of milliseconds to wait after the last keystroke before sending a `t:LiveSelect.ChangeMsg.t/0` message. Defaults to 100ms.
* `search_term_min_length` - the minimum length of text in the search field that will trigger an update of the dropdown. It has to be a positive integer. Defaults to 3.
* `style` - either `:daisyui` for daisyui styling (default) or `:none` for no styling. See the "Styles" section above.
* `container_class` - See the "Styles" section above for this and the following options.
* `container_extra_class`
* `text_input_class`
* `text_input_extra_class`
* `text_input_selected_class`
* `dropdown_class`
* `dropdown_extra_class`
* `active_option_class`
"""
def live_select(form, field, opts \\ [])
when (is_binary(field) or is_atom(field)) and is_list(opts) do
form_name = if is_struct(form, Phoenix.HTML.Form), do: form.name, else: to_string(form)
assigns =
opts
|> Map.new()
|> Map.put(:id, "#{form_name}_#{field}_component")
|> Map.put(:module, LiveSelect.Component)
# Ecto forms expect atom fields:
# https://github.com/phoenixframework/phoenix_ecto/blob/master/lib/phoenix_ecto/html.ex#L123
|> Map.put(:field, String.to_atom("#{field}"))
|> Map.put(:form, form)
~H"""
<.live_component {assigns} />
"""
end
@doc ~S"""
Updates a `LiveSelect` component with new options. `change_msg` must be the `t:LiveSelect.ChangeMsg.t/0` originally sent by the LiveSelect,
and `options` is the new list of options that will be used to fill the dropdown.
Each option will be assigned a label, which will be shown in the dropdown, and a value, which will be the value of the
LiveSelect input when the option is selected.
`options` can be any enumerable of the following elements:
* _atoms, strings or numbers_: In this case, each element will be both label and value for the option
* _tuples_: `{label, value}` corresponding to label and value for the option
* _maps_: `%{label: label, value: value}`
* _keywords_: `[label: label, value: value]`
This means you can use maps and keyword lists to pass the list of options, for example:
```
%{Red: 1, Yellow: 2, Green: 3}
```
Will result in 3 options with labels `:Red`, `:Yellow`, `:Green` and values 1, 2, and 3.
Note that the option values, if they are not strings, will be JSON-encoded. Your LiveView will receive this JSON-encoded version in the `phx-change` and `phx-submit` events.
"""
def update_options(%ChangeMsg{module: module, id: component_id} = _change_msg, options),
do: Phoenix.LiveView.send_update(module, id: component_id, options: options)
end
