New cop for Hash#dig

[Ana06]

Add a new cop that enforce the use of

params.dig(:user, :name)

instead of

params[:user] && params[:user][:name]

---

Concerns

When using symbol as key I would say that the complain and the autocorrect are always safe, but not in the following cases:

Strings

Due to the str[match_str] method, things like this happens:

params = { "user" => "Nicolas Cage" } => {"user"=>"Nicolas Cage"}

params.dig("user","age") => TypeError: String does not have #dig method

params["user"] && params["user"]["age"] => "age"

Integers

The same for integers:

params = { "user" => "Nicolas Cage" } => {"user"=>"Nicolas Cage"}

params.dig("user",1) => TypeError: String does not have #dig method

params["user"] && params["user"][1] => "i"

And that's the reason why I think it may be not safe that this cop check for Array#dig as well, as in this case numbers are always use and we get things like:

array=["hola"] => ["hola"]

array.dig(0,1) => TypeError: String does not have #dig method

array[0] && array[0][1] => "o"

For these cases we could add in the Ruby style guide that dig is preferred. I would say those cases are not the normal ones but still maybe not possible that a cop look for them.

[Ana06]

@Ana06

When using symbol as key I would say that the complain and the autocorrect are always safe

The method are not exactly equivalente with symbols as well:

params = { "user": { name: "Nicolas Cage", married: false } }
  => {:user=>{:name=>"Nicolas Cage", :married=>false}}

params[:user] && params[:user][:married] && params[:user][:married][:date]
  => false

params.dig(:user, :married, :date)
  => TypeError: FalseClass does not have #dig method
             from (irb):6:in `dig'
             from (irb):6
             from /usr/bin/irb.ruby2.4:11:in `<main>'

I am not sure if this can be safely implemented. 🤔

[tjwp]

I wrote a custom cop to do this: https://github.com/ezcater/ezcater_rubocop/blob/master/lib/rubocop/cop/ezcater/style_dig.rb

We've found it useful, but it is definitely susceptible to false positives, e.g. ranges also have to be excluded.

I wouldn't enable it by default for rubocop.

[Ana06]

@tjwp what about sending a PR to Rubocop? 😉

I wouldn't enable it by default for rubocop.

yes, me neither 😉

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contribution and understanding!

[stale]

This issues been automatically closed due to lack of activity. Feel free to re-open it if you ever come back to it.