link_to.md

link_to

link_to(body, url, html_options = {})
link_to(body, url_options = {}, html_options = {})
link_to(options = {}, html_options = {}) do

name

end
link_to(url, html_options = {}) do

name

end

Examples

Because it relies on url_for, link_to supports both older-style controller/action/id arguments and newer RESTful routes. Current Rails style favors RESTful routes whenever possible, so base your application on resources and use

link_to "Profile", profile_path(@profile)
html <a href="/profiles/1">Profile</a>
or the even pithier

link_to "Profile", @profile
html <a href="/profiles/1">Profile</a>
in place of the older more verbose, non-resource-oriented

link_to "Profile", :controller => "profiles", :action => "show", :id => @profile
html <a href="/profiles/show/1">Profile</a>
Similarly,

link_to "Profiles", profiles_path
html <a href="/profiles">Profiles</a>
is better than

link_to "Profiles", :controller => "profiles"
html <a href="/profiles">Profiles</a>
You can use a block as well if your link target is hard to fit into the name parameter. ERB example:

<%= link_to(@profile) do %> <strong><%= @profile.name %></strong> -- <span>Check it out!</span> <% end %>

  <strong>David</strong> -- <span>Check it out!</span></a>```
  
Classes and ids for CSS are easy to produce:

link_to "Articles", articles_path, :id => "news", :class => "article"<br>
```html <a href="/articles" class="article" id="news">Articles</a>```

<h1>link_to_if</h1>

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

<h1>link_to_unless</h1>
```<%= link_to_unless(@current_user.nil?, "Reply", { :action => "reply" }) %>```<br>
If the user is logged in...<br>
```=> <a href="/controller/reply/">Reply</a>```

<h1>link_to_unless_current</h1>
```html
<ul id="navbar">
  <li><%= link_to_unless_current("Home", { :action => "index" }) %></li>
  <li><%= link_to_unless_current("About Us", { :action => "about" }) %></li>
</ul>

• Home
• About Us

Why Bother?

• Adjusting URLs through abstraction.


• ...?


• Profit!

form_for

form_for creates a form and a scope around a specific model object that is used as a base for questioning about values for the fields.

Assume we have a controller for dealing with articles app/controllers/posts_controller.rb:

def new
  @post = Post.new
end

def edit
  @post = Post.find(params[:id])
end

The corresponding view app/views/posts/new.html.erb using form_for looks like this:

<%= form_for @post do |f| %>
  <%= f.text_field :title %>
  <%= f.text_area :body, :size => "60x12" %>
  <%= f.submit "Create" %>
<% end %>

The resulting HTML is:

<form accept-charset="UTF-8" action="/posts/create" method="post">
  <input id="post_title" name="post[title]" size="30" type="text" />
  <textarea id="post_body" name="post[body]" cols="60" rows="12"></textarea>
  <input name="commit" type="submit" value="Create" />
</form>

Keep in mind that this: ```ruby <%= form_for @post do |f| %> ... <% end %> ``` is equivalent to something like:

<%= form_for @post, :as => :post, :url => posts_path, :html => { :class => "new_post", :id => "new_post" } do |f| %>
  ...
<% end %>

and if @post is an existing record you want to edit: ```ruby <%= form_for @post do |f| %> ... <% end %> ``` this is equivalent to something like: ```ruby <%= form_for @post, :as => :post, :url => post_path(@post), :method => :put, :html => { :class => "edit_post", :id => "edit_post_45" } do |f| %> ... <% end %> ```

The image_tag helper

---

Syntax: image_tag(source, options = {}) public

Returns an html image tag for the source. The source can be a full path or a file that exists in your public images directory.

#####Examples:

image_tag("icon")  # =>
  <img src="/images/icon" alt="Icon" />
image_tag("icon.png")  # =>
  <img src="/images/icon.png" alt="Icon" />
image_tag("icon.png", :size => "16x10", :alt => "Edit Entry")  # =>
  <img src="/images/icon.png" width="16" height="10" alt="Edit Entry" />
image_tag("/icons/icon.gif", :size => "16x16")  # =>
  <img src="/icons/icon.gif" width="16" height="16" alt="Icon" />
image_tag("/icons/icon.gif", :height => '32', :width => '32') # =>
  <img alt="Icon" height="32" src="/icons/icon.gif" width="32" />
image_tag("/icons/icon.gif", :class => "menu_icon") # =>
  <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
image_tag("mouse.png", :mouseover => "/images/mouse_over.png") # =>
  <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />
image_tag("mouse.png", :mouseover => image_path("mouse_over.png")) # =>
  <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />

The image assets are to be kept in /app/assets/images

###Why use image_tag instead of ?

It's less to write. Compare:

image_tag('foo') vs. <img src="/images/foo.png" />

Asset timestamping. Those are those funny numbers on the end. They are the timestamp of the file. This allows you to enable HTTP caching of images forever but still allow them to expire when you update the image.

image_tag("rails.png")
# => <img alt="Rails" src="http://assets.example.com/images/rails.png?1230601161" />

You can configure your static assets to be stored on a different server that is built to serve static resources quickly. A simple config change and all your images change from:

<img src="/images/foo.png?63565665" />

to

<img src="http://assets.yourcompany.com/images/foo.png?63565665" />