phoenix-controllers

# Phoenix Controllers

Phoenix controllers are the intermediary modules between the router and views in a Phoenix application. They handle HTTP requests, process parameters, interact with contexts, and determine what response to send back to the client. Controllers are stateless and receive a connection struct (`conn`) that represents the current HTTP request.

## Basic Controller Structure

The simplest Phoenix controller uses the `HelloWeb, :controller` macro and defines actions as functions that receive the connection and parameters:

```elixir
defmodule HelloWeb.PageController do
  use HelloWeb, :controller

  def home(conn, _params) do
    render(conn, :home, layout: false)
  end
end
```

Each controller action receives:

- `conn` - The `Plug.Conn` struct representing the HTTP request/response
- `params` - A map containing request parameters from the URL, query string, and request body

## Controller Actions and Parameter Handling

### Extracting Specific Parameters

Use pattern matching to extract specific parameters from the params map:

```elixir
defmodule HelloWeb.HelloController do
  use HelloWeb, :controller

  def show(conn, %{"messenger" => messenger}) do
    render(conn, :show, messenger: messenger)
  end
end
```

### Accessing Full Parameter Map

To access both a specific parameter and the full params map, use pattern matching with the `=` operator:

```elixir
def show(conn, %{"messenger" => messenger} = params) do
  # Access to both messenger and the full params map
  render(conn, :show, messenger: messenger)
end
```

### Ignoring Parameters

When an action doesn't need parameters, prefix the variable with an underscore to avoid compiler warnings:

```elixir
def index(conn, _params) do
  render(conn, :home)
end
```

### Renaming Actions

Action names can be customized independently of the template name:

```elixir
defmodule HelloWeb.PageController do
  use HelloWeb, :controller

  def index(conn, _params) do
    # Renders :home template but action is