I have this code-snippet in html erb.
For some objects the cover_image_url is empty, how do i modify this code block to use a default value ,when that property is null or empty?
<%@books.each do |book|%>
$('#bookContainer').append('<div class="conn"><p><img class="floatright" src="<%= h book.cover_image_url%>"><h3><%= h book.title%></h3><h3><%= h book.author%></h3></p></div>');
<% end %>
You could define a cover_image_url method on your book model that will return a default value if there is nothing set in the database (I am assuming that cover_image_url is a column in the book table). Something like this:
class Book < ActiveRecord::Base
def cover_image_url
read_attribute(:cover_image_url).presence || "/my_default_link"
end
end
This will return "/my_default_link" if the attribute is not set, or the value of the attribute if it is set. See section 5.3 on The Rails 3 Way for more info on this stuff. Defining a default value for a model in the model layer may be a little cleaner than doing it in the view layer.
read_attribute(:cover_image_url).presence || "/my_default_link". presence returns the object if it isn't blank, otherwise returns nil.self[:amount] not read_attribute(:amount)You can use a local variable inside the loop :
<% url = book.cover_image_url or "/my_default_link" %>
This will take a default link if the first value is nil.
To check both null or empty :
<% url = ((book.cover_image_url.nil? or (book.cover_image_url and book.cover_image_url.empty?)) ? "/my_default_link" : book.cover_image_url) %>
Put the whole thing in a helper to make it cleaner.
url = book.cover_image_url || "/my_default_link"