# Flop Phoenix
 [](https://hex.pm/packages/flop_phoenix) [](https://coveralls.io/github/woylie/flop_phoenix)
Flop Phoenix provides Phoenix components for pagination, sortable tables, and
filter forms with [Flop](https://hex.pm/packages/flop) and
[Ecto](https://hex.pm/packages/ecto).
## Installation
To start using flop_phoenix, add it to your list of dependencies in `mix.exs`
of your Phoenix application:
Add `flop_phoenix` to your list of dependencies in the `mix.exs` of your Phoenix
application.
```elixir
def deps do
[
{:flop_phoenix, "~> 0.23.0"}
]
end
```
Next, set up your business logic according to the
[Flop documentation](https://hex.pm/packages/flop).
## Usage
First, define a function that utilizes `Flop.validate_and_run/3` to query your
desired list. For example:
```elixir
defmodule MyApp.Pets do
alias MyApp.Pet
def list_pets(params) do
Flop.validate_and_run(Pet, params, for: Pet)
end
end
```
### LiveView
In the LiveView, fetch the data and assign it alongside the meta data to the
socket.
```elixir
defmodule MyAppWeb.PetLive.Index do
use MyAppWeb, :live_view
alias MyApp.Pets
@impl Phoenix.LiveView
def handle_params(params, _, socket) do
case Pets.list_pets(params) do
{:ok, {pets, meta}} ->
{:noreply, assign(socket, %{pets: pets, meta: meta})}
{:error, _meta} ->
# This will reset invalid parameters. Alternatively, you can assign
# only the meta and render the errors, or you can ignore the error
# case entirely.
{:noreply, push_navigate(socket, to: ~p"/pets")}
end
end
end
```
If you prefer the `Flop.Phoenix` components not to reflect pagination, sorting,
and filtering parameters in the URL, fetch and assign the data in the
`c:Phoenix.LiveView.handle_event/3` callback. You need to pass a
`Phoenix.LiveView.JS` command as an attribute to the components in that case.
### Controller
For non-LiveView ("dead") views, pass the data and Flop meta struct to your
template in the controller.
```elixir
defmodule MyAppWeb.PetController do
use MyAppWeb, :controller
alias MyApp.Pets
action_fallback MyAppWeb.FallbackController
def index(conn, params) do
with {:ok, {pets, meta}} <- Pets.list_pets(params) do
render(conn, :index, meta: meta, pets: pets)
end
end
end
```
## Sortable tables and pagination
To add a sortable table and pagination links, you can add the following to your
template:
```elixir
Pets
<:col :let={pet} label="Name" field={:name}><%= pet.name %>
<:col :let={pet} label="Age" field={:age}><%= pet.age %>
```
In this context, path points to the current route, and Flop Phoenix appends
pagination, filtering, and sorting parameters to it. You can use verified
routes, route helpers, or custom path builder functions. You'll find
explanations for the different formats in the documentation for
`Flop.Phoenix.build_path/3`.
Note that the field attribute in the `:col` slot is optional. If set and the
corresponding field in the schema is defined as sortable, the table header for
that column will be interactive, allowing users to sort by that column. However,
if the field isn't defined as sortable, or if the field attribute is omitted, or
set to `nil` or `false`, the table header will not be clickable.
By using the `for` option in your Flop query, Flop Phoenix can identify which
table columns are sortable. Additionally, it omits the `order` and `page_size`
parameters if they align with the default values specified via `Flop.Schema`.
You also have the option to pass a `Phoenix.LiveView.JS` command instead of or
in addition to a path. For more details, please refer to the component
documentation.
To change the page size, you can either add an HTML `input` control (see below) or
add a LiveView `handle_event/3` function with a corresponding control, such
as a link. For example, you might create a widget with several page-size links.
You could create a `page_size_link` component like this:
```elixir
attr :current_size, :integer, required: true
attr :new_size, :integer, required: true
def page_size_link(assigns) do
~H"""
<.link
phx-click="page-size"
phx-value-size={@new_size}
class={page_size_class(@current_size, @new_size)}
>
<%= @new_size %>
"""
end
defp page_size_class(old, old), do: "font-black text-orange-500"
defp page_size_class(_old, _new), do: "font-light"
```
You could then render them like this:
```elixir
<.page_size_link :for={ps <- [10, 20, 40, 60]} new_size={ps} current_size={@meta.page_size} />
```
Then, you can handle the event in your LiveView, like this:
```elixir
def handle_event("page-size", %{"size" => ps}, socket) do
flop = %{socket.assigns.meta.flop | page_size: ps, limit: nil}
path = Flop.Phoenix.build_path(~p"/pets", flop)
{:noreply, push_patch(socket, to: path)}
end
```
This method allows you to update the page size while maintaining browser history.
If you wish to implement cursor-based pagination, see
`Flop.Phoenix.cursor_pagination/1` for setup instructions.
## Filter forms
Flop Phoenix implements the `Phoenix.HTML.FormData` for the `Flop.Meta` struct.
As such, you can easily pass the struct to Phoenix form functions. One
straightforward way to render a filter form is through the
`Flop.Phoenix.filter_fields/1` component, as shown below:
```elixir
attr :fields, :list, required: true
attr :meta, Flop.Meta, required: true
attr :id, :string, default: nil
attr :on_change, :string, default: "update-filter"
attr :target, :string, default: nil
def filter_form(%{meta: meta} = assigns) do
assigns = assign(assigns, form: Phoenix.Component.to_form(meta), meta: nil)
~H"""
<.form
for={@form}
id={@id}
phx-target={@target}
phx-change={@on_change}
phx-submit={@on_change}
>
<.filter_fields :let={i} form={@form} fields={@fields}>
<.input
field={i.field}
label={i.label}
type={i.type}
phx-debounce={120}
{i.rest}
/>
"""
end
```
Note that while the `filter_fields` component produces all necessary hidden
inputs, it doesn't automatically render inputs for filter values. Instead, it
passes the necessary details to the inner block, allowing you to customize the
filter inputs with your custom input component.
One such hidden input is the input for `page_size`. If you would like to display this field, you can simply add a direct HTML input control for `page_size` to your `filter_form/1` function, like so:
```elixir
...
"""
end
```
You can pass additional options for each field. Refer to the
`Flop.Phoenix.filter_fields/1` documentation for details.
Now, you can render a filter form like so:
```elixir
<.filter_form
fields={[:name, :email]}
meta={@meta}
id="user-filter-form"
/>
```
You will need to handle the `update-filter` event with the `handle_event/3`
callback function of your LiveView.
```elixir
@impl true
def handle_event("update-filter", params, socket) do
params = Map.delete(params, "_target")
{:noreply, push_patch(socket, to: ~p"/pets?#{params}")}
end
```
## LiveView streams
To use LiveView streams, you can change your `handle_params/3` function as
follows:
```elixir
def handle_params(params, _, socket) do
case Pets.list_pets(params) do
{:ok, {pets, meta}} ->
{:noreply,
socket
|> assign(:meta, meta)
|> stream(:pets, pets, reset: true)}
# ...
end
end
```
When using LiveView streams, the data being passed to the table component
differs. Instead of passing `@pets`, you'll need to use `@streams.pets`.
The stream values are tuples, with the DOM ID as the first element and the items
(in this case, Pets) as the second element. You need to match on these tuples
within the `:let` attributes of the table component.
```elixir
<:col :let={{_, pet}} label="Name" field={:name}><%= pet.name %>
<:col :let={{_, pet}} label="Age" field={:age}><%= pet.age %>
```