rodry has asked for the wisdom of the Perl Monks concerning the following question:

I have the following code for a function

sub MysqlIN {

my %dateparts = ( YEAR => '', MONTH => '', DAY => '', @_, );
my $element;

foreach $element (%dateparts) {
if (!$dateparts{$element}) {
   die "Invalid date value";
   exit;
}

my $mysqldate = join ("-", $dateparts{YEAR}, $dateparts{MONTH}, $datep
+art{DAY});

return $mysqldate;
}

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For some reason, the test inside the foreach loop is always true. What I want to accomplish with this function is simple: verify that the arguments have number values (not done yet) and that they are not empty.

Thanks for the help.

Replies are listed 'Best First'.
Re: Validating hash values
by reptile (Monk) on Sep 16, 2000 at 03:13 UTC

    You need to change that foreach to be keys %dateparts. As it is, it's going over both the keys and the values, and when it gets to value, it's false because that key doesn't exist yet. 

    foreach my $element (keys %dateparts) { ... }

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    local $_ = "0A72656B636148206C72655020726568746F6E41207473754A";
while(s/..$//) { print chr(hex($&)) }

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Re: Validating hash values
by tye (Sage) on Sep 16, 2000 at 03:18 UTC 
    sub MysqlIN {
    my %dateparts= ( YEAR => '', MONTH => '', DAY => '', @_ );
    my $element;
    foreach $element ( keys %dateparts ) {
        if (  0 < $dateparts{$element}  ) {
            die "Invalid date value";
        }
    }
    my $mysqldate= join "-", @dateparts{qw(YEAR MONTH DAY)};
    return $mysqldate;
}

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            - tye (but my friends call me "Tye")
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(crazyinsomniac) Re: Validating hash values
by crazyinsomniac (Prior) on Sep 16, 2000 at 03:12 UTC
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Re: Validating hash values
by geektron (Curate) on Sep 16, 2000 at 03:21 UTC
    you need a combination of two of the replies: 
    foreach my $element ( keys %dateparts ) {
    die "No datepart!: $!" unless defined $dateparts{$element};
}

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    the 'exit' is redundant. if the code dies, the program is exiting.

    i also don't think your assignment is going to work correctly. if you're passing in date values, you really should just use something like: 

    my %dateparts = @_;

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    assuming that your input args are in the form of: 

    sub MySQLIN( YEAR => '1999', DAY => '10', MONTH => '3');

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    the join will work even if the values to join are undefined.

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      But if you don't initialize the hash, then passing in no arguments won't be properly detected, for example.

              - tye (but my friends call me "Tye")
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(ar0n) Re: Validating hash values
by ar0n (Priest) on Sep 16, 2000 at 03:24 UTC
    tye beat me to it. see his post above. oh well, just ignore me :)

    I'd change 
    my $mysqldate = join ("-", $dateparts{YEAR}, $dateparts{MONTH}, $datep
+art{DAY});

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    into 
    my $mysqldate = join ("-", @dateparts{ qw(YEAR MONTH DAY) });

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    @dateparts{qw(YEAR MONTH DAY)} is just an easier way of saying 
    @dateparts{("YEAR", "MONTH", "DAY")}

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    which is an easy way of saying
    ($dateparts{YEAR}, $dateparts{MONTH}, $datepart{DAY})

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    -- ar0n (just another perl joe)

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Re: Validating hash values
by isotope (Deacon) on Sep 16, 2000 at 03:14 UTC
    Uhhh... maybe you'd have more success using defined and $var ne "" and the like.

    --isotope
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      When testing if a hash key is defined, its better to use exists.
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RE: Validating hash values
by runrig (Abbot) on Sep 16, 2000 at 03:25 UTC
    Update: Never mind, there's enough responses here already

    As mentioned before, you need to change that loop. Here is my offering:

    sub MysqlIN {

# Why is that '@_' in there, are you passing in an
# array of three values?
# That's what I'll assume, so I'll change this line
#my %dateparts = ( YEAR => '', MONTH => '', DAY => '', @_, );
# To this:
my %dateparts = ( YEAR=>shift, MONTH=>shift, DAY=>shift );
my $element;

while (my ($name, $value) = each %dateparts) {
 # Number validation added
 die "Invalid value for $name" unless $value and $value=~/^\d+$/;
 # You don't need to exit, you already died!
 # exit;
}

my $mysqldate = join ("-", @dateparts{qw(YEAR MONTH DAY)});

return $mysqldate;
}

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