Custom sort array of hashes based on multiple key/value pairs

Question

I have an array of hashes which I need to sort based on two different key value pairs.

Here is the array I am trying to sort:

array_group =  [
 {operator: OR, name: "some string", status: false},
 {operator: AND, name: "other string", status: false},
 {operator: _NOT_PRESENT, name: "another string", status: true},
 {operator: AND, name: "just string", status: true}
]

I want to sort array_group so I have items with status: true first, followed by status: false, followed by the items with operator: _NOT_PRESENT and finally sort it based on name, resulting in something like:

array_group = [
 {operator: AND, name: "just string", status: true},
 {operator: AND, name: "other string", status: false},
 {operator: OR, name: "some string", status: false},
 {operator: _NOT_PRESENT, name: "another string", status: true},
]

Is there a way that I can get this done without creating sub-arrays and sorting them and concatenating them back?

Answer 1

You can also use Enumerable#sort_by. The example builds an array which is compared element by element when sorting.

array_group.sort_by { |e| [e[:operator] == "_NOT_PRESENT" ? 1 : 0, 
                           e[:status] ? 0 : 1, 
                           e[:name]] }

The example above orders records with operator: "_NOT_PRESENT" also by :status. The following snippet precisely performs the ordering from the question.

def priority(h)
  case
  when h[:operator] == "_NOT_PRESENT" then 3
  when h[:status] == false            then 2
  # h[:status] == true
  else 1
  end
end

array_group.sort_by { |e| [priority(e), e[:name]] }

Answer 2

You can use the Array.sort method. It accepts a block with two arguments (x, y), when x is larger than y it should return 1, otherwise -1, and 0 if they are equal.

The code:

OR = "OR"
AND = "AND"
_NOT_PRESENT = "_NOT_PRESENT"

array_group =  [
 {operator: OR, name: "some string", status: false},
 {operator: AND, name: "other string", status: true},
 {operator: _NOT_PRESENT, name: "another string", status: true},
 {operator: AND, name: "just string", status: true}
]

results = array_group.sort do |x, y|
  next x[:operator] == _NOT_PRESENT ? 1 : -1 if x[:operator] == _NOT_PRESENT || y[:operator] == _NOT_PRESENT
  next x[:status] ? -1 : 1 if x[:status] != y[:status]
  next x[:name] <=> y[:name]
end

And btw, you your input and output data doesn't match each other — the hash with OR is false in the input, but true in the output.

I believe your output should look like:

[{:operator=>"AND", :name=>"just string", :status=>true},
 {:operator=>"AND", :name=>"other string", :status=>true},
 {:operator=>"OR", :name=>"some string", :status=>false},
 {:operator=>"_NOT_PRESENT", :name=>"another string", :status=>true}]

That output will actually match your sorting logic.