Nilbogger Gem
This gem was created to protect against undefined method __ for nil:NilClass errors. It's often difficult to anticipate the shape of complex JSON objects from web requests. The goal of this gem is to reduce the amount of lines of code that look like:
response.parse && response.parse.data && response.parse.data[0] && response.parse.data[0].weather && response.parse.data[0].weather.temp
(Chained ifs and ternary operators are also out.)
Installation
Gemfile: gem 'nilbogger'
Install: gem install nilbogger
Usage
NoMethodError
fruit_colors = {banana: 'yellow', orange: 'orange', avocado: 'green'}
p fruit_colors[:banana].upcase
# => "YELLOW"
p fruit_colors[:apple]
# => nil
p fruit_colors[:apple].upcase
# => undefined method `upcase' for nil:NilClass (NoMethodError)
With Nilbogger:
p Nilbogger::nil_try{ fruit_colors[:banana].upcase }
# => "YELLOW"
p Nilbogger::nil_try{ fruit_colors[:apple].upcase }
# => nil
Using Nilbogger custom return values:
p Nilbogger::nil_try(false){
fruit_colors[:banana].upcase }
# => "YELLOW"
p Nilbogger::nil_try(false){
fruit_colors[:apple].upcase }
# => false
Other Errors
Nilbogger::try{ x = a }
p "code continues to run"
# => "code continues to run"
p Nilbogger.errors
# => [#<NameError: undefined local variable or method `a' for main:Object>]
Nilbogger::try also accepts an optional custom return value
p Nilbogger::try{ x = a }
# => #<NameError: undefined local variable or method `a' for main:Object>
p Nilbogger::try(false){ x = b }
# => false
p Nilbogger::errors
# => [#<NameError: undefined local variable or method `a' for main:Object>, #<NameError: undefined local variable or method `b' for main:Object>]
Nilbogger::nil_try will also populate the errors array while allowing the code to run when executing an error other than NoMethodError. (Custom return values don't work in this case, though.)
p Nilbogger::nil_try{ x = a }
# => #<NameError: undefined local variable or method `a' for main:Object>
p Nilbogger::nil_try(false){ x = b }
# => #<NameError: undefined local variable or method `b' for main:Object>
p Nilbogger::errors
# => [#<NameError: undefined local variable or method `a' for main:Object>,
#<NameError: undefined local variable or method `b' for main:Object>]