Rails best practice for displaying partial if condition is true - ruby-on-rails

Question

In my controller, I'm getting all of a user's associated #highinterest accounts, and I'm adding the sum of the value column:
#dohighinterest = Account.where(user_id: current_user, accounttype: 'Savings', name: ['GE Capital Bank', 'Barclays', 'CIT Bank', 'Bank5 Connect', 'Ally Bank', 'Discover', 'First Choice Bank', 'FNBO Direct', 'Mutual of Omaha', 'Sallie Mae Bank', 'American Express Bank', 'Capital One 360'])
#highinterest = #dohighinterest.sum(&:value)
Later on in the controller, I'm defining variables so that the view knows which class to render.
if #highinterest > (#rechighinterest * 0.8) && (#highinterest < (#rechighinterest * 1.2))
#highrec = "pass"
elsif #highinterest > (#rechighinterest * 0.6) && (#highinterest < (#rechighinterest * 1.4))
#highrec = "okay"
else
#highrec = "fail"
end
Here's the view:
<div class="rollup <%= #highrec %>">
<p>You're gaining interest on</p>
<div class="percentage">
$<%= number_with_delimiter(#highinterest, :delimiter => ',') %>
</div>
</div>
Additionally, I'd like to render a partial in the view if #highrec = "fail" and #highinterest = 0.
What's the best practice for putting that logic into the controller and view? I attempted to define a new variable in the controller #rectext = true if it meets that condition. Then in the view, I wrapped the partial reference to an <%= if #rectext = true %>, but that wasn't returning anything.

Answer 1

I don't think you need a separate variable to hold value of #highrec == "fail" && #highinterest == 0. You can use this same condition in your view. If however there are more variables in play, you could introduce a variable to keep the view cleaner!
<% if #highrec == "fail" && #highinterest == 0 %>
<%= render partial: 'path_to_other_partial' %>
<% else %>
<div class="rollup <%= #highrec %>">
<p>You're gaining interest on</p>
<div class="percentage">
$<%= number_with_delimiter(#highinterest, :delimiter => ',') %>
</div>
</div>
<% end %>
The line you tried <%= if #rectext = true %> would result in syntax error because of <%= tag, which is trying to output the value returned by if #rectext = true. So, a point to note would be, using <%= tag is going to output the value returned by the statements within the tags and <%(without the equals) is going to evaluate only without printing!
Secondly, you are assigning #rectext = true in the if statement, it should be a comparision, i.e. either if #rectext == true or just if #rectext.

Answer 2

You can define a helper method inside folder app/helpers/controllername_helper.rb that recieves the values of #highrec and #highinterest as parameters and then returns true or false depending on your needs.
Then in the view call the method this way:
<% if helper_method_name(#highrec, #highinterest) %>
<%= render partial: 'partial_path' %>
<% end %>
Note that in this code you write :
<%= if #rectext = true %>
you are assigning #rectext the value true and not checking if it is true. Also in this case you should use <% instead of <%=