How can I accomplish this?
<% for agent in @broker.agents %>
...
<% if agent.cell %><span class="cell-number">Cell: <%= agent.cell %></span><% end %>
...
<% end %>
I want to test to see if the agent has a cell number, and if so, display what's inside the conditional. What I have currently doesn't seem to work; it just displays "Cell: ".
Thoughts?
This is what you asked for:
<% for agent in @broker.agents %>
<% unless agent.cell.blank? %>
<span class="cell-number">Cell: <%= agent.cell %></span>
<% end %>
<% end %>
The cell? method works whether cell is nil or an empty string. Rails adds similar functions for all ActiveRecord attributes. This will look a little nicer:
<% for agent in @broker.agents %>
<span class="cell-number">
Cell: <%= agent.cell? ? "none given" : agent.cell %>
</span>
<% end %>
The question mark and colon form a quick "if ? then : else" statement. There are two question marks in the code above because one is part of the method name cell? and the other is a part of the if/then/else construction.
I am giving a very detailed answer to this Question "How do I check if a column has a value?".
First of all, it is important to note that an attribute can have four kinds of values in it.
Here is the detail behavior of all the present methods(Ruby 2.2.2) that could be used in this case.
First Method: .empty?
For nil value => Throws an exception
2.2.2 :037 > object.attribute
=> nil
2.2.2 :025 > object.attribute.empty?
NoMethodError: undefined method `empty?' for nil:NilClass
For empty value i.e "" an empty string with no spaces
2.2.2 :037 > object.attribute
=> ""
2.2.2 :025 > object.attribute.empty?
true
empty string with spaces " ".
2.2.2 :041 > object.attribute
=> " "
2.2.2 :042 > object.attribute.empty?
=> false
value present in database i.e a non-empty string.
2.2.2 :045 > object.attribute
=> "some value"
2.2.2 :046 > object.attribute.empty?
=> false
Second Method: .nil?
nil value i.e "nil" stored in the database
2.2.2 :049 > object.attribute
=> nil
2.2.2 :050 > object.attribute.nil?
=> true
empty value i.e "" an empty string with no spaces
2.2.2 :053 > object.attribute
=> ""
2.2.2 :054 > object.attribute.nil?
=> false
empty string with spaces " ".
2.2.2 :057 > object.attribute
=> " "
2.2.2 :058 > object.attribute.nil?
=> false
value present in database i.e a non-empty string.
2.2.2 :061 > object.attribute
=> "some value"
2.2.2 :062 > object.attribute.nil?
=> false
Third Method: .blank?
nil value i.e "nil" stored in the database
2.2.2 :065 > object.attribute
=> nil
2.2.2 :066 > object.attribute.blank?
=> true
empty value i.e "" an empty string with no spaces
2.2.2 :069 > object.attribute
=> ""
2.2.2 :070 > object.attribute.blank?
=> true
empty string with spaces " ".
2.2.2 :073 > object.attribute
=> " "
2.2.2 :074 > object.attribute.blank?
=> true
value present in database i.e a non-empty string.
2.2.2 :075 > object.attribute
=> "some value"
2.2.2 :076 > object.attribute.blank?
=> false
Fourth Method: .present?
nil value i.e "nil" stored in the database
2.2.2 :088 > object.attribute
=> nil
2.2.2 :089 > object.attribute.present?
=> false
empty value i.e "" an empty string with no spaces
2.2.2 :092 > object.attribute
=> ""
2.2.2 :093 > object.attribute.present?
=> false
empty string with spaces " ".
2.2.2 :096 > object.attribute
=> " "
2.2.2 :097 > object.attribute.present?
=> false
value present in database i.e a non-empty string.
2.2.2 :100 > object.attribute
=> "some value"
2.2.2 :101 > object.attribute.present?
=> true
You can use either of the four depending upon the situation you face.
Thanks
if !agent.cell.blank?
It works.
<% @broker.agents.each do |agent| %>
...
<% unless agent.cell.empty? %>
<span class="cell-number">Cell: <%= agent.cell %></span>
<% end %>
...
<% end %>
I find the use of #each, unless, and cell.empty? to be more readable and easier to understand at first glance.
you can actually check if the column contains nothing by doing
Model.column == "" will return true if the column type is string
