Re: [HACKERS] string_to_array with empty input

On Mar 31, 2009, at 8:34 AM, Sam Mason wrote:

>> What do you really expect to be returned for things like
>>
>> select count_elements(string_to_array('butter,tea,milk',','))

3 = {butter,tea,milk}

>> select count_elements(string_to_array('butter,tea',','))

2 = {butter,tea}

>> select count_elements(string_to_array('butter',','))

1 = {butter}

>> select count_elements(string_to_array('',','))

1 = ARRAY['']

> I'd expect 3,2,1 and 1.
>
> That's also a disingenuous example; what would you expect back from:
>
> select count_elements(string_to_array('butter,,milk',','))

3 = ARRAY['butter', '', 'milk']

> I think the semantics you want is what you'd get from:
>
> array_filter_blanks(string_to_array($1,$2))
>
> where I defined "array_filter_blanks" in my previous post.

Yeah, if I wanted something like that in Perl, I'd do:

my @stuff = grep { $_ } split /,/, $string;

In no case would I ever expect a NULL, however, unless I was trying to
split on NULL.

NULL = string_to_array(NULL, ',');

Best,

David