/ Ruby on Rails
/
method

link_to_if

rails latest stable - Class: ActionView::Helpers::UrlHelper
link_to_if(condition, name, options = {}, html_options = {}, &block)
public

Creates a link tag of the given name using a URL created by the set of options if condition is true, otherwise only the name is returned. To specialize the default behavior, you can pass a block that accepts the name or the full argument list for link_to_if.

Examples

<%= link_to_if(@current_user.nil?, "Login", { controller: "sessions", action: "new" }) %>
# If the user isn't logged in...
# => <a href="/sessions/new/">Login</a>

<%=
   link_to_if(@current_user.nil?, "Login", { controller: "sessions", action: "new" }) do
     link_to(@current_user.login, { controller: "accounts", action: "show", id: @current_user })
   end
%>
# If the user isn't logged in...
# => <a href="/sessions/new/">Login</a>
# If they are logged in...
# => <a href="/accounts/show/3">my_username</a>

6Notes

link_to_if for named routes

eric_programmer · Dec 29, 20085 thanks

Back before named routes we used to say things like:

<%= link_to_if message.user, 'Poster', :controller => 'users',
:action => 'show', :id => message.user %>

This would make the text "Poster" only link if message has a user. But with named routes this has become more complicated. Our first try is something like:

<%= link_to_if message.user, 'Poster', user_path(message.user) %>

Although this looks nice it causes an error since the path is generated prior to the condition not after the condition like using a hash is done. To get around this problem I have found two solutions:

  • If you are linking to the "show" path then you can just pass the object. This will force the path to not be generated until after the condition (like a hash is done). For example:

    <%= link_to_if message.user, 'Poster', message.user %>

  • The previous workaround works great if you want to link to the show action. But what if you want to link to another action (say the edit action). In this case the best way I have found is to use the hash_for* helpers generated with the routing resource. So:

    <%= link_to message.user, 'Poster', hash_for_edit_user_path(:id => message.user) %>

A little more awkward than the previous workaround but it is the best I can come up with. Any other suggestions (other than going back to manually typing the hash)?

link to nothing if link_to_if condition is false

concept47 · Dec 1, 20104 thanks

When the link_to_if condition is false you can get this helper to display nothing by doing something like this

<%= link_to_if(message.user, 'Poster', message.user){} %>

^ That will display nothing if message.user does not exist.

Outputs name even if condition is false

szeryf · Oct 30, 20092 thanks

Please note that if the condition is false, link_to_if will still output the name given as a plain text (as documented above). If you want nothing printed at all, you'll have to stay with the old and trusty:

link_to "Login", ... if @current_user.nil?

Outputs name even if condition is false

szeryf · Oct 30, 2009

Please note that if the condition is false, link_to_if will still output the name given as a plain text (as documented above). If you want nothing printed at all, you'll have to stay with the old and trusty:

link_to "Login", ... if @current_user.nil?

If condition is false, options hash is ignored

stevenspiel · Mar 30, 2015

Here, the class will be ignored:

<%= link_to_if false, 'Home', root_path, class: 'link' %> 
#=> Home

Passing a block does not behave as expected

stevenspiel · Mar 30, 2015

When the condition is true, the block is not rendered:

<%= link_to_if true, users_path, {}, {} do %>
<i class='fa fa-star'></i>
<% end %>

renders:

<a href="/users">/users</a>

But if the condition is false, the block will render:

<%= link_to_if false, users_path, {}, {} do %>
<i class='fa fa-star'></i>
<% end %>

renders: