joshsarna / nilbogger

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>]