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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?
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To convert an array to a comma-separated string, call the join() method on the array, passing it a string containing a comma as a parameter. The join method returns a string containing all array elements joined by the provided separator.
Ruby | Array class join() function join() is an Array class method which returns the string which is created by converting each element of the array to a string, separated by the given separator.
The join() method creates and returns a new string by concatenating all of the elements in an array (or an array-like object), separated by commas or a specified separator string. If the array has only one item, then that item will be returned without using the separator.
When you want just the comma character ( , ) to appear as the separator between items in the list, use . join(",") to convert the array to a string. As you can see, there will never be an extra comma after the last item, meaning your entire array is now joined together as one string.
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"
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"
I think you have nil elements in your array. You can do this:
arr.compact.join(", ")
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).
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