Rails: Cheatsheet

Rails Cheatsheet

# Debug
## In a view
<%= debug @object %>
<%= debug 'string' %>
<%= 'string'.inspect %>

##In a controller / model
logger.debug "The object is #{@object}"
RAILS_DEFAULT_LOGGER.debug @object

## Controllers only
return render :text => "The object is #{@object}"

## Exceptions
# exception class
class CustomException < Exception; end
# create an exception
CustomException.new("This is the exception message")

# catch the exception
begin
 # block of code
rescue CustomException.new=> e
      render :text => e.to_s, :content_type => 'text/plain', :status => 500
rescue Exception => e  
  # deal with other errors  
else  
  # good, no exception surfaced!  
ensure  
  # good or bad, this needs to be done  
end

# best practises
# never catch all the exceptions, be specific
# Do not place return or break in ensure sections and try to avoid throwing exceptions from them.
# Place rescue clauses for more specific exceptions (sub classes) before those for less specific ones (super classes).
# rescue the most specific exception you can handle.
# Do not rescue exceptions that you cannot or do not want to handle.

# Models

## Touch
user.updated_at #=> "Wed Jan 27 23:29:22 +1300 2010"
user.touch
user.updated_at #=> "Wed Jan 27 23:30:08 +1300 2010"

## deep clone
deep_cloned = Marshal::load(Marshal.dump(origin))

Ruby: Cheatsheet

# Debug
## In a view
<%= debug @object %>
<%= debug 'string' %>
<%= 'string'.inspect %>

##In a controller / model
logger.debug "The object is #{@object}"
RAILS_DEFAULT_LOGGER.debug @object

## Controllers only
return render :text => "The object is #{@object}"

## Exceptions
# exception class
class CustomException < Exception; end
# create an exception
CustomException.new("This is the exception message")

# catch the exception
begin
 # block of code
rescue CustomException.new=> e
      render :text => e.to_s, :content_type => 'text/plain', :status => 500
rescue Exception => e  
  # deal with other errors  
else  
  # good, no exception surfaced!  
ensure  
  # good or bad, this needs to be done  
end

# best practises
# never catch all the exceptions, be specific
# Do not place return or break in ensure sections and try to avoid throwing exceptions from them.
# Place rescue clauses for more specific exceptions (sub classes) before those for less specific ones (super classes).
# rescue the most specific exception you can handle.
# Do not rescue exceptions that you cannot or do not want to handle.

# Models

## Touch
user.updated_at #=> "Wed Jan 27 23:29:22 +1300 2010"
user.touch
user.updated_at #=> "Wed Jan 27 23:30:08 +1300 2010"

## deep clone
deep_cloned = Marshal::load(Marshal.dump(origin))

- Comments
# TODO
# FIXME
# OPTIMIZE
# MATT
then run `rake notes` or `rake notes:fixme` or `rake notes:custom ANNOTATION=MATT`

- Run helper methods from the console
helper.number_to_currency(100)

- Show database status
rake db:migrate:status

- Merge nested hashes
{nested: {one: 1}}.deep_merge{nested: {two: 2}}