# `PhoenixPageMeta.Site`
[🔗](https://github.com/exfoundry/phoenix_page_meta/blob/v0.1.0/lib/phoenix_page_meta/site.ex#L1)

Behaviour for site-wide PageMeta callbacks.

Implemented by the project's PageMeta module (e.g. `MyAppWeb.PageMeta`).
Both callbacks have sensible defaults injected by `use PhoenixPageMeta`,
so you only implement them if your project deviates from the convention.

## Default implementations (via `use PhoenixPageMeta`)

  * `base_url/0` — returns the configured `:base_url` option (string or
    function-of-arity-0). When omitted, guesses the Endpoint from the
    module's namespace (e.g. `MyAppWeb.PageMeta` → `MyAppWeb.Endpoint.url()`).
  * `lang_path/2` — locale-prefix swap on `:path` (e.g. `/en/foo` → `/de/foo`).

Both are `defoverridable` — provide your own implementation if needed:

    defmodule MyAppWeb.PageMeta do
      use PhoenixPageMeta

      @enforce_keys [:title, :path]
      defstruct [...]

      @impl PhoenixPageMeta.Site
      def lang_path(%__MODULE__{} = page_meta, locale) do
        # Custom routing scheme — e.g. query string instead of path prefix
        page_meta.path <> "?lang=" <> to_string(locale)
      end
    end

# `base_url`

```elixir
@callback base_url() :: String.t()
```

Returns the absolute base URL of the site (e.g. `"https://example.com"`).
Used to build canonical and og:url tags.

# `lang_path`

```elixir
@callback lang_path(page_meta :: struct(), locale :: atom()) :: String.t()
```

Returns the localized path for a page in a given locale. Used to render
hreflang alternate links. Only called when a page has `:supported_locales`
set.

---

*Consult [api-reference.md](api-reference.md) for complete listing*