How do I pass mutiple column names to Perl Dancer's quick_select method?

Question

I'm trying to use Perl Dancer quick_select to quickly fetch rows from the database. I'm using a list of items from the user that I got like this: my @arr=split(/,/, $inline);

I keep getting this error when using the items from the user:

DBD::mysql::db selectall_arrayref failed: Unknown column 'val2' in 'where clause'

This does not work:

my @rows = $connect->quick_select('table', { column => @arr});

But this does work:

my @rows = $connect->quick_select('table', { column => ['val1', 'val2']});`

Apparently [] denotes a list but @arr is an array in Perl? So I've tried converting it to a list but this also does not work:

my @rows = $connect->quick_select('table', { column => @arr[0..$#arr]});

The table and column names have been changed to protect the data. How can I fix this so quick_select will work with dynamic data from the user?

Dancer doesn't have a `quick_select` function. I assume you're using a Dancer plugin to add that to your program. It would be helpful if you could tell us where it comes from. — Dave Cross, Jul 20 '17 at 08:34

stevieb · Answer 1 · 2017-07-22T22:34:09.377

3

Apparently [] denotes a list but @arr is an array in Perl? So I've tried converting it to a list but this also does not work.

That's not correct. [] denotes an array reference in Perl. An array is an ordered list of scalars indexed by number, and an array reference is a scalar that "points to" an array.

You can take the array you scoop up from $input, take a reference to it with the \@array syntax, and send it in that way:

my @rows = $connect->quick_select('table', { column => \@arr});

You can take that one step further (at possibly some cost to clarity) by forcing the call to split into an array reference inline:

my @rows = $connect->quick_select('table', { column => [split(/,/, $inline)] });

edited Jul 22 '17 at 22:34

answered Jul 19 '17 at 17:35

stevieb

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Nice that worked! Thanks! I usually don't use Perl, all these symbols can be confusing. – Chip Dean Jul 19 '17 at 17:37
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*"An array is a list"* No, it is not. Arrays and lists are [very different things](https://perldoc.perl.org/perlfaq4.html#What-is-the-difference-between-a-list-and-an-array%3f). – Borodin Jul 19 '17 at 17:41
@Borodin I was updating to say "a type of list" while you were typing that. – stevieb Jul 19 '17 at 17:42
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@stevieb: I don't agree with that either. – Borodin Jul 19 '17 at 17:45
@Borodin How's "an array is a variable that can hold a list of values"? – stevieb Jul 19 '17 at 17:47
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See `perldoc perldata`: "*arrays are ordered lists of scalars indexed by number*". – Sinan Ünür Jul 19 '17 at 18:02
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Updated to reflect the quote from `perldata`. – stevieb Jul 19 '17 at 18:08

How do I pass mutiple column names to Perl Dancer's quick_select method?

1 Answers1