The FAQs of RuboCup

RuboCop is a Ruby static code analyzer and code formatter which helps to track errors easily and fix minor code issues during the development process saving your time. It has many advantages and you can learn more about RuboCop on . https://docs.rubocop.org/en/stable/ Today, we will be talking about the most asked questions about RuboCop. 11 Most Asked Questions About RuboCop 1. How to check if record exists from controller in Rails? Answer: How to test if at least one record exists? Using Option 1: .exists? Business.exists?(user_id: current_user.id) # same Business.where(user_id: current_user.id).exists? # ... else # ... end if as Using (or , the opposite of ) Option 2: .present? .blank? .present? Business.where(: current_user.id).present? # less efficiant than using .exists? (see generated SQL .exists? vs .present?) # ... end if => user_id for else Variable assignment in the if statement Option 3: business = Business.where(: current_user.id).first business.do_some_stuff # something end if => user_id else do else This option can be considered a code smell by some linters (RuboCop for example). Variable assignment Option 3b: business = Business.where(user_id: current_user.id).first business # ... else # ... end if You can also use instead of . .find_by_user_id(current_user.id) .where(...).first Best option: If you don’t use the object(s): Business Option 1 If you need to use the object(s): Business Option 3 Alternative Answer: In this case, you can use the method provided by ActiveRecord: exists? Business.exists? user_id: current_user.id 2. How to ignore lines with comments? Answer: There is a way to ignore cops on a per-line basis. There is also a way to do it via the configuration file. Run and it will generate a file that you can use to disable the offenses. rubocop --auto-gen-config The command also gives a hint on what to do to load those options. On a line per line basis, you can enable and disable the cops as well. # rubocop:disable RuleByName This is a long line # rubocop:enable RuleByName You can also do more than one rule at a time in your code. # rubocop:disable BlockComments, AsciiComments By using an inline directive, the directive becomes valid only for that line, and it would look like this: method(argument) # rubocop:disable SomeRule, SomeOtherRule Alternative Answer: It’s possible to define regex patterns to automatically ignore certain lines in , so you could choose to ignore all lines starting with a character: rubocop.yml # Metrics/LineLength: Max: IgnoredPatterns: [ ] 80 '\A#' This could be improved so that “indented” comment lines (i.e. whitespace followed by a character) is also ignored if that’s what you want. # Note that this doesn’t account for lines of code that with a comment, though: end some_code(that_does_something) # This line would NOT be ignored by Rubocop. 3. How to split Ruby regex over multiple lines? Answer: You need to use the modifier, which enables . /x free-spacing mode Like in this case: =~ x "bar" /(foo| bar)/ Alternative Answer: Using %r with the x option is the preferred way to do this. See this example from the GitHub ruby style guide regexp = %r{ start # some text \s # white space char (group) # first group (?:alt1|alt2) # some alternation end }x regexp.match? "start groupalt2end" 4. RuboCop: Line is too long ← How to Ignore? Answer: You can disable a bunch of lines like this: # rubocop:disable LineLength puts # rubocop:enable LineLength "This line is lonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnng" Or add this to your file to increase the max length: .rubocop.yml Metrics/LineLength: Max: 100 Alternative Answer: Creating a file (keep an eye on the initial . in the filename) in the root of your project, you’ll have a bunch of options: .rubocop.yml Metrics/LineLength: # This will disable the rule completely, regardless what other options you put Enabled: # Change the chars limit value Max: # If you want the rule only apply to a specific folder/file Include: - # If you want the rule not to apply to a specific folder/file Exclude: - false default 80 120 'app/**/*' 'db/schema.rb' 5. What is meant by ‘Assignment Branch Condition Size too high’ and how to fix it? Answer: Assignment Branch Condition (ABC) size is a measurement of the size of a method. It is essentially determined by counting the number of ssignments, ranches, and onditional statements. A B C To reduce the ABC score, you could move some of those assignments into before_action calls: before_action , [ , , ] before_action , [ , , ] before_action , [ , , ] rate private = Category.friendly.find(params[ ]) = Category.all = category.products.approved.order( ).ransack(params[ ]) = .result.page(params[ ]).per( ) :fetch_current_category only: :show :edit :update :fetch_categories only: :show :edit :update :fetch_search_results only: :show :edit :update #or whatever def show end def fetch_current_category @category :id end def fetch_categories @categories end def fetch_search_results @search updated_at: :desc :q @products @search :page 50 end How to tell RuboCop to ignore a specific directory or file? 6. Answer: You can add the following to .rubocop.yml: AllCops: Exclude: - 'path/to/excluded/file.rb' where the path is relative to .rubocop.yml Alternative Answer: From : rubocop/default.yml AllCops: Exclude: - - 'node_modules/**/*' 'vendor/**/*' 7. How to integrate RuboCop with Rake? Answer: The simple answer is just adding this to your Rakefile: task test: :rubocop task :rubocop sh end do 'rubocop' Alternative Answer: As of version RuboCop contains a custom rake task that you can use. Just put the following in your . 0.10.0 Rakefile RuboCop::RakeTask.new require 'rubocop/rake_task' Make sure to use upper-case ‘R’ and ‘C’ or you will get a NameError. 8. How to silence RuboCop warning on Assignment Branch Condition? Answer: This is the message for the Metrics/AbcSize cop. # rubocop:disable Metrics/AbcSize Alternative Answer: On your RuboCop config Metrics/AbcSize: Enabled: false 9. How to disable frozen string literal comment checking? Answer: Add the following to your : .rubocop.yml Style/FrozenStringLiteralComment: Enabled: false 10. How to pass &:key as an argument to map instead of a block with Ruby? Answer: Pass &:key as an argument to map instead of a block. Meaning: my.objects.map(&:key) 11. How to fix “SublimeLinter-RuboCop not running even when enabled and RuboCop in the path”? Answer: First, specify the right path for you ruby env in as this: Packages/User/SublimeLinter.sublime-settings { ... : { : [], : [ ], : [] }, ... } "paths" "linux" "osx" "~/.rbenv/shims/" "windows" After that close sublime completely and reopen it. In Conclusion These are the most asked questions about the RuboCop. If you have any suggestions or any confusion, please comment below. If you need any help, we will be glad to help you. We, at , provide services like web and mobile app development, digital marketing, and website development. So, if you need any help and want to work with us, please feel free to contact us. Truemark Hope this article helped you. This post was originally posted on DevPost by Truemark