Rails method for concatenate

Question

Is it possible to concatenate Array ['a', 'b', 'c'] to String "a, b and c" ?
But ['a', 'b'] should transform to "a and b".

Answer 1

Rails provides a to_sentence helper:

> ['a', 'b'].to_sentence
 => "a and b" 
> ['a', 'b', 'c'].to_sentence
 => "a, b, and c" 

If you want a, b and c rather than a, b, and c you can change the last_word_connector:

> ['a', 'b', 'c'].to_sentence(last_word_connector: " and ")
 => "a, b and c"