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

Per-page metadata for Phoenix LiveView apps: breadcrumbs, active-link state,
SEO meta tag rendering.

## Setup

In your project's PageMeta module:

    defmodule MyAppWeb.PageMeta do
      use PhoenixPageMeta

      @enforce_keys [:title, :path]
      defstruct [
        :title,
        :path,
        :breadcrumb_title,
        :parent,
        :description,
        :og_image,
        :json_ld,
        :canonical_path,
        :icon,
        :skip_breadcrumb,
        og_type: "website",
        noindex: false,
        supported_locales: [:en, :es]
      ]
    end

That's it. No `config.exs` entry. The macro provides default implementations
of `base_url/0` (auto-detected from the module's namespace, e.g.
`MyAppWeb.PageMeta` → `MyAppWeb.Endpoint.url()`) and `lang_path/2`
(locale-prefix swap on `:path`). Both are `defoverridable` if you need a
different scheme.

## use options

  * `:base_url` — accepts a string (`"https://example.com"`) or a 0-arity
    function capture (`&MyAppWeb.Endpoint.url/0`). When omitted, the macro
    guesses the Endpoint module from your PageMeta's namespace.

## In LiveViews

In `MyAppWeb.live_view/0`:

    def live_view do
      quote do
        use Phoenix.LiveView, layout: ...
        @behaviour PhoenixPageMeta.LiveView
        import PhoenixPageMeta.LiveView, only: [assign_page_meta: 1]
      end
    end

In each LiveView:

    defmodule MyAppWeb.SomeLive do
      use MyAppWeb, :live_view

      @impl PhoenixPageMeta.LiveView
      def page_meta(_socket, _action) do
        %MyAppWeb.PageMeta{title: "Hello", path: "/hello"}
      end

      def mount(_params, _session, socket) do
        {:ok, assign_page_meta(socket)}
      end
    end

See `PhoenixPageMeta.Breadcrumb`, `PhoenixPageMeta.Components.Breadcrumbs`,
`PhoenixPageMeta.Components.MetaTags`, `PhoenixPageMeta.Site`, and
`PhoenixPageMeta.LiveView`.

# `__using__`
*macro* 

Injects the PhoenixPageMeta wiring into a project PageMeta module.

Adds `@behaviour PhoenixPageMeta.Site`, default implementations of
`base_url/0` and `lang_path/2` (both `defoverridable`), wrappers for
`breadcrumbs/1` and `active?/2,3` that match the project struct, and an
`@after_compile` hook that validates the struct has the required fields.

# `active?`

Returns true if the given link path matches the current page or one of its
ancestor paths.

## Options

  * `:exact` — when `true`, only matches the current page exactly. Default `false`.
  * `:query` — when `true`, query strings are part of the comparison. When
    `false` (default), they are stripped from both sides before matching.

## Matching rules

Without `:exact`, a link is active if its path equals the current path or is
a prefix followed by `/`. So `/locations` matches `/locations` and
`/locations/123`, but not `/location-foo`.

Most projects call this via the project module's wrapper (e.g.
`MyAppWeb.PageMeta.active?/2,3`), which restricts the input type via
`%MyAppWeb.PageMeta{}` pattern. The lib-level function accepts any struct.

---

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