Is there an opposite function of slice function in Ruby?

Question

In this post, slice function is used to get only necessary elements of params. What would be the function I should use to exclude an element of params (such as user_id)?

Article.new(params[:article].slice(:title, :body))

Thank you.

Answer 1

Use except:

a = {"foo" => 0, "bar" => 42, "baz" => 1024 }
a.except("foo")
# returns => {"bar" => 42, "baz" => 1024}

Answer 2

Try this

params = { :title => "title", :other => "other", :body => "body"  }

params.select {|k,v| [:title, :body].include? k  } #=> {:title => "title", :body => "body"}  

Answer 3

Inspired in the sourcecode of except in Rails' ActiveSupport

You can do the same without requiring active_support/core_ext/hash/except

# h.slice( * h.keys - [k1, k2...] )

# Example:
h = { a: 1, b: 2, c: 3, d: 4 }
h.slice( * h.keys - [:b, :c] ) # => { a: 1, d: 4}

Note: Ruby 3+ Hash incorporated this except method:

# Ruby 3+
h.except(:b, :c) # => { a: 1, d: 4}

Answer 4

Considering only standard Ruby.

For Ruby versions below 3, no.

For Ruby 3, yes. You can use except.