I have the following .erb view in a Sinatra app:
<% sessions.each do |session| %>
<%= session.balance_beginning %>
<%= session.balance_ending %>
<% end %>
It works as expected, displaying the beginning and ending balances recorded for each session. I would like to calculate the net balances from within the .erb file, but I can't figure out how to do it. I have tried variations of this:
<% sessions.each do |session| %>
<%= session.balance_ending - session.balance_beginning %>
<% end %>
That doesn't work. I receive the following error in Sinatra:
undefined method `-' for nil:NilClass
How do I do what I'm trying to do?
Right #Zabba, in this case I think you would add a method to your Session model so you could call session.net_balance.
Then in your balance_ending and balance_beginning methods you would want to handle nil, either raise an error or return zero if that is valid.
Related
Note that I cannot use Rails or Javascript.
Is there any way to repeat a block of HTML code using only Ruby / ERB?
In Rails I would do this:
<% content_for :mycontent do %>
some html code
that I want to capture
etc
<% end %>
Then, here, in the same template, I can reuse the block...
<%= content_for :mycontent %>
Multiple times...
<%= content_for :mycontent %>
Is there any equivalent without Rails?
Im trying to display all the images from active storage on an index page. Note: The image will display in the show page
Heres what i have on the index page:
<% #imagelists.each do |il| %>
<%= image_tag(#il.image) &>
<% end %>
I can do the following which shows the active storage data
<% #imagelists.each do |il| %>
<%= #il.image &>
<% end %>
When you do this:
<% #imagelists.each do |il| %>
You are defining a variable il which is available within that each block.
However, in your code you are referencing #il - an instance variable which doesn't exist. Unlike a normal variable, when you reference an instance variable which isn't defined, you just get nil, not a NoMethodError.
So, just use il instead of #il and you'll be fine.
I'm using Sinatra and I'd like to include another erb file in one of my views but using a variable for the file name.
I was thinking something like this may work but I get an error saying no such file could be found.
<%= erb :'layout/nav/#{device_type}' %>
Currently I'm using the below switch statement to achieve the desired results but the above would be cleaner and less code.
<% case device_type
when 'mobile'%>
<%= erb :'layout/nav/mobile' %>
<% when 'tablet' %>
<%= erb :'layout/nav/tablet' %>
<% else %>
<%= erb :'layout/nav/desktop' %>
<% end %>
Thanks
Giles
I think that could work, you just need to use double quotes to interpolate strings.
Try
<%= erb :"layout/nav/#{device_type}" %>
I'm trying to write some puppet .erb, I'd like to handle this "environment" variable if it's:
undefined
a string with newlines
an array.
I've got as far as this:
<% Array(environment).join("\n").split(%r{\n}).each do |f| %>
one line: <%= f %>
<% end %>
But haven't gotten around the undefined case yet. I've tried this
<% if (defined?(environment)).nil? %?
<% Array(environment).join("\n").split(%r{\n}).each do |f| %>
one line: <%= f %>
<% end %>
<% end %>
but am still getting "(erb):11: undefined local variable or method `environment' for main:Object (NameError)" when trying to test it like this:
ruby -rerb -e "environmentUNDEFINEME= [ 'cronvar=cronval', 'var2=val2' ];
puts ERB.new(File.read('templates/job.erb')).result"
Sorry this is so basic, but somebody's got to ask the easy questions. Any help?
I would do this:
<% if defined?(environment) %>
<% Array(environment).each do |f| %>
one line: <%= f %>
<% end %>
<% end %>
I didn't understand why you joining on new lines and then splitting on them again, so I removed it from the example.
I have a _form which renders another form with simple_fields_for. Everything works fine except I can't figure out the symbol that holds the different URLs, I particularly want the thumb URL.
For example, picture.image_uploader_url — but I don't have the actual object, just the :pictures symbol which is being iterated on. So far :image_uploader_url.to_s doesn't give anything useful and I realized this is because that will always just give the symbol name.
Super form:
<%= simple_form_for(#project) do |f| %>
[...]
<%= f.simple_fields_for :pictures do |builder| %>
<%= render "pictures/form", f: builder %>
[...]
Sub form (pictures/_form):
<% unless [:image_uploader_url].nil? or [:image_uploader_url].empty? %>
<%= image_tag(:thumb_url.to_s) %>
<% end %>
<%= f.input :name %>
<%= f.input :description %>
<%= f.input :image_uploader, as: :file %>
<%= f.hidden_field :image_uploader_cache %>
How do I know in general what symbols I will have access to and how do I use them? maybe I dont have them?
EDIT: I don't have 'picture' to work with, only ':pictures' which I'm struggling to find what all I can get from this (i.e. picture has an image_uploader which I can get image_uploader_url(:thumb) but I can't do this with symbols, nor do I know how to get the picture that is the current iteration).
To get the thumb url for picture, just do this: picture.thumb.url. To get the original url, picture.url would do fine.
As far as I could figure out there is no way to get to the individual pictures that are related to the :pictures symbol. I ended up just scrapping the symbol and passing local variables (I was trying to avoid having the controller from making more information directly available).
I still don't have a satisfactory answer but this is the best I could come up with.