Array join with commas, only when element is not nil

Question

Is there a starightforward way to achieve array.join(", ") where the comma is only included between elements that exist? I.e., if some elements don't exist in the array, I don't end up getting orphan commas?

Answer 1

Example:

["", nil, "test word", 5, 7, nil, "", nil, "", 7, 6, ""] => "test word, 5, 7, 7, 6"

Edit: Please note that the first method here requires Ruby on Rails. Use the second method for a Ruby-only solution

You can try this to remove both nil and empty strings "" and then join with commas (It removes all nil values with compact, then it does split on "" to create a two-dimensional array where any "" elements in the first array are just empty arrays in the new 2D array, then it does flatten which turns the 2D array back into a normal array but with all the empty arrays removed, and finally it does the join(", ") on this array):

> array.compact.split("").flatten.join(", ")


array = ["", nil, "test word", 5, 7, nil, "", nil, "", 7, 6, ""]

array.compact => ["", "test word", 5, 7, "", "", 7, 6, ""].split("") => [[], ["test word", 5, 7], [], [7, 6], []].flatten => ["test word", 5, 7, 7, 6].join(", ") => "test word, 5, 7, 7, 6"

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Edit: Another way would be:

> array.reject(&:blank?).join(", ")


array = ["", nil, "test word", 5, 7, nil, "", nil, "", 7, 6, ""]

array.reject(&:blank?) => ["test word", 5, 7, 7, 6].join(", ") => "test word, 5, 7, 7, 6"

Answer 2

I think you have nil elements in your array. You can do this:

arr.compact.join(", ")

Answer 3

It seems you need to compact the array before join. It returns a copy of array without nil elements.

http://ruby-doc.org/core-2.2.0/Array.html#method-i-compact

[1,nil,2,3].compact.join(', ')

You can also use compact! to remove the nil elements from the source array itself (without making a copy).