When we write ERB views in Rails, etc., we generally DRY up the markup using helpers or partials.
However, it's quite common to overdo the 'DRYing up'.
When you find yourself passing in optional arguments to a helper/partial such as :extra_text => 'eggs', :to_s_method => 'cheese'
, you know that there must be a better way.
Rails already has a great solution for forms with form-builders, using helpers which yield an object which can be used for further rendering.
This small gem generates helpers similar to the form-builders, but for the general case.
Please note that these examples are very contrived just for brevity! These block helpers are much more useful than just printing 'Hi there Marmaduke!'
In the helper file:
module MyHelper
class MyBlockHelper < ActionView::BlockHelper
def hello(name)
"<p>Hi there #{name}!</p>"
end
end
end
This has generated a helper called my_block_helper
.
So in the view:
<% my_block_helper do |h| %>
Here goes...
<%= h.hello('Marmaduke') %>
...hooray!
<% end %>
This will generate the following:
Here goes...
<p>Hi there Marmaduke!</p>
...hooray!
Methods available in the parent helper are available to the block helper class.
In case of name clashes, you can also access those methods via the protected object helper
.
In the helper:
module MyHelper
def angry
"I'm very angry"
end
class MyBlockHelper < ActionView::BlockHelper
def angry
content_tag :div, helper.angry
end
end
end
In the view:
<% my_block_helper do |h| %>
<%= h.angry %>
<% end %>
This generates:
<div>I'm very angry</div>
You can pass in arguments to the helper, and these will be passed through to the class's options
method.
In the helper:
module MyHelper
class MyBlockHelper < ActionView::BlockHelper
def options(tag_type)
@tag_type = tag_type
end
def hello(name)
content_tag @tag_type, "Hi there #{name}!"
end
end
end
In the view:
<% my_block_helper(:span) do |h| %>
<%= h.hello('Marmaduke') %>
<% end %>
This generates:
<span>Hi there Marmaduke!</span>
Use the display
method to surround the block with markup, e.g.
In the helper:
module MyHelper
class RoundedBox < ActionView::BlockHelper
def display(body)
%(
<div class="tl">
<div class="tr">
<div class="bl">
<div class="br">
#{body}
</div>
</div>
</div>
</div>
)
end
end
end
In the view:
<% rounded_box do %>
Oi oi!!!
<% end %>
This generates:
<div class="tl">
<div class="tr">
<div class="bl">
<div class="br">
Oi oi!!!
</div>
</div>
</div>
</div>
Of course, you could use display
for more than just surrounding markup.
To use in Rails, add to your environment.rb
:
config.gem "markevans-block_helpers", :lib => "block_helpers", :source => "http://gems.github.com"
- Mark Evans (author)
- Nathan Esquenazi and 2collegebums (contributor)
Copyright (c) 2009 Mark Evans. See LICENSE for details.