When used, defines the current module as a main view module.

Options

• :root - the template root to find templates
• :path - the optional path to search for templates within the :root. Defaults to the underscored view module name. A blank string may be provided to use the :root path directly as the template lookup path
• :namespace - the namespace to consider when calculating view paths
• :pattern - the wildcard pattern to apply to the root when finding templates. Default "*"

The :root option is required while the :namespace defaults to the first nesting in the module name. For instance, both MyApp.UserView and MyApp.Admin.UserView have namespace MyApp.

The :namespace and :path options are used to calculate template lookup paths. For example, if you are in MyApp.UserView and the namespace is MyApp, templates are expected at Path.join(root, "user"). On the other hand, if the view is MyApp.Admin.UserView, the path will be Path.join(root, "admin/user") and so on. For explicit root path locations, the :path option can be provided instead. The :root and :path are joined to form the final lookup path. A blank string may be provided to use the :root path directly as the template lookup path.

Setting the namespace to MyApp.Admin in the second example will force the template to also be looked up at Path.join(root, "user").

Converts a module, without the suffix, to a template root.

Examples

iex> Phoenix.View.module_to_template_root(MyApp.UserView, MyApp, "View")
"user"

iex> Phoenix.View.module_to_template_root(MyApp.Admin.User, MyApp, "View")
"admin/user"

iex> Phoenix.View.module_to_template_root(MyApp.Admin.User, MyApp.Admin, "View")
"user"

iex> Phoenix.View.module_to_template_root(MyApp.View, MyApp, "View")
""

iex> Phoenix.View.module_to_template_root(MyApp.View, MyApp.View, "View")
""

Renders a template.

It expects the view module, the template as a string, and a set of assigns.

Notice that this function returns the inner representation of a template. If you want the encoded template as a result, use render_to_iodata/3 instead.

Examples

Phoenix.View.render(YourApp.UserView, "index.html", name: "John Doe")
#=> {:safe, "Hello John Doe"}

Assigns

Assigns are meant to be user data that will be available in templates. However, there are keys under assigns that are specially handled by Phoenix, they are:

• :layout - tells Phoenix to wrap the rendered result in the given layout. See next section

Layouts

Templates can be rendered within other templates using the :layout option. :layout accepts a tuple of the form {LayoutModule, "template.extension"}.

To template that goes inside the layout will be placed in the @inner_content assign:

<%= @inner_content %>

Renders a template only if it exists.

Note: Using this functionality has been discouraged in recent Phoenix versions, see the "Alternatives" section below.

This function works the same as render/3, but returns nil instead of raising. This is often used with Phoenix.Controller.view_module/1 and Phoenix.Controller.view_template/1, which must be imported into your views. See the "Examples" section below.

Alternatives

This function is discouraged. If you need to render something conditionally, the simplest way is to check for an optional function in your views.

Consider the case where the application has a sidebar in its layout and it wants certain views to render additional buttons in the sidebar. Inside your sidebar, you could do:

<div class="sidebar">
  <%= if function_exported?(view_module(@conn), :sidebar_additions, 1) do %>
    <%= view_module(@conn).sidebar_additions(assigns) %>
  <% end %>
</div>

If you are using Phoenix.LiveView, you could do similar by accessing the view under @socket:

<div class="sidebar">
  <%= if function_exported?(@socket.view, :sidebar_additions, 1) do %>
    <%= @socket.view.sidebar_additions(assigns) %>
  <% end %>
</div>

Then, in your view or live view, you do:

def sidebar_additions(assigns) do
  ~H\"""
  ...my additional buttons...
  \"""

Using render_existing

Consider the case where the application wants to allow entries to be added to a sidebar. This feature could be achieved with:

<%= render_existing view_module(@conn), "sidebar_additions.html", assigns %>

Then the module under view_module(@conn) can decide to provide scripts with either a precompiled template, or by implementing the function directly, ie:

def render("sidebar_additions.html", _assigns) do
  ~H"""
  ...my additional buttons...
  """
end

To use a precompiled template, create a scripts.html.eex file in the templates directory for the corresponding view you want it to render for. For example, for the UserView, create the scripts.html.eex file at your_app_web/templates/user/.

Renders the given layout passing the given do/end block as @inner_content.

This can be useful to implement nested layouts. For example, imagine you have an application layout like this:

# layout/app.html.heex
<html>
<head>
  <title>Title</title>
</head>
<body>
  <div class="menu">...</div>
  <%= @inner_content %>
</body>

This layout is used by many parts of your application. However, there is a subsection of your application that wants to also add a sidebar. Let's call it "blog.html". You can build on top of the existing layout in two steps. First, define the blog layout:

# layout/blog.html.heex
<%= render_layout LayoutView, "app.html", assigns do %>
  <div class="sidebar">...</div>
  <%= @inner_content %>
<% end %>

And now you can simply use it from your controller:

plug :put_layout, "blog.html"

Alternatives

render_layout/4 is discouraged in favor of components. If you need to share functionality, you can create components with bits of functionality you want to reuse. For example, the code above could be rewritten with a layout component:

def layout(assigns) do
  ~H"""
  <div ...>
    <%= render_slot(@sidebar) %>
    <%= render_slot(@inner_block) %>
  </div>
  """
end

Which can be used as:

<.layout>
  Main content
</.layout>

Or:

<.layout>
  <:sidebar>Additional sidebar content</:sidebar>
  Main content
</.layout>

The advantage of using components is that you can handle all of the sidebar markup inside the parent layout component, instead of spreading it across multiple files.

Renders a collection.

It receives a collection as an enumerable of structs and returns the rendered collection in a list. This is typically used to render a collection as structured data. For example, to render a list of users to json:

render_many(users, UserView, "show.json")

which is roughly equivalent to:

Enum.map(users, fn user ->
  render(UserView, "show.json", user: user)
end)

The underlying user is passed to the view and template as :user, which is inferred from the view name. The name of the key in assigns can be customized with the :as option:

render_many(users, UserView, "show.json", as: :data)

is roughly equivalent to:

Enum.map(users, fn user ->
  render(UserView, "show.json", data: user)
end)

Renders a single item if not nil.

The following:

render_one(user, UserView, "show.json")

is roughly equivalent to:

if user != nil do
  render(UserView, "show.json", user: user)
end

The underlying user is passed to the view and template as :user, which is inflected from the view name. The name of the key in assigns can be customized with the :as option:

render_one(user, UserView, "show.json", as: :data)

is roughly equivalent to:

if user != nil do
  render(UserView, "show.json", data: user)
end

Renders the template and returns iodata.

Renders the template and returns a string.

@spec template_path_to_name(Path.t(), Path.t()) :: Path.t()

Converts the template path into the template name.

Examples

iex> Phoenix.View.template_path_to_name(
...>   "lib/templates/admin/users/show.html.eex",
...>   "lib/templates"
...> )
"admin/users/show.html"