content_tag

There is a difference between an empty string and nil value for options hash. ==== Code Sample content_tag( :div, 'Hello World!', :class=>'') # => "

" content_tag( :div, 'Hello World!', :class=>nil) # => ""

If you want to output an empty element (self-closed) like "br", "img" or "input", use the +tag+ method instead.

Remember to use #collect instead of #each in nested content_tags arr = ['a','b','c'] content_tag :div do arr.collect { |letter| content_tag(:scan, letter) end #=>

If you used #each you would get this (which is probably a mistake): #=>

This piece of syntax saves me allot of time. Note the if statement.

==== Code example content_tag(:div, "Hello World", :class => ("active" if i_am_an_active_item?))

At least in 3.0.5, some of the previous examples no longer work: ActionView seems to quietly ignore Array content.

If you were using code of the form

content_tag(:li, nil, :class => 'someClass') {
arr.collect { |x|
  content_tag(:ul, x)
}
}

it now needs to look like

content_tag(:li, nil, :class => 'someClass') {
arr.reduce('') { |c, x|
  c << content_tag(:ul, x)
}.html_safe
}

Content_tag works great in a helper and is a nice way to clean up your views.

If you're returning more than one content_tag you'll need to concat them:

@content = content_tag(:tr, "first item")
@content << content_tag(:tr, "second item")

Be mindful that when doing the above, you must use parentheses around the content_tag options. In the above example, content_tag :tr, "second item" will return an error.

The earlier reminder to use #collect instead of #each applies regardless of whether the tag is nested or not.

This is counterintuitive, as #collect returns an array of strings of HTML tags, but ActionView renders it properly.

You can still use collect when you nest +content_tag+ . Just +join+ the collection in the end and remember to add +html_safe+ if you don't want your html to be escaped.

a = ['a','b','c']
content_tag(:ul, :class => 'a class') do
a.collect do |item|
  content_tag(:li, item)
end.join.html_safe
end