Beefy Boxes and Bandwidth Generously Provided by pair Networks
Problems? Is your data what you think it is?

Re^3: How to use a json string with nested array and nested hash elements?

by Anonymous Monk
on Feb 04, 2013 at 12:50 UTC ( #1016942=note: print w/replies, xml ) Need Help??

in reply to Re^2: How to use a json string with nested array and nested hash elements?
in thread How to use a json string with nested array and nested hash elements?

Well, as aitap mentioned above, @jsonarray = $decoded_json->{strarray} is wrong; it should be $jsonarray = $decoded_json->{strarray}. (It makes no sense to call ref() on an array either.)

Anyway, since $strarray is an array reference, you access its elements with $strarray->[$index], and if you need the whole array (in the foreach), you need to write @$strarray. (With hashes, the equivalents are $somevar->{$key} and %$somevar, respectively.)

Your structure is... well, let's tackle the strarray. It is an array of a single element, and that element contains a hash. And that is where you went wrong. I think you missed the arrays altogether. There's one under pick_location and the other one was under strarray. But let's try this in code:

# let's use an intermediate variable. # it's a good idea when dealing with complex data structures my $strarray = $decoded_json->{strarray}; # enumerate over the first array. for my $str (@$strarray) { # now you have a hash with refill_report # and inventory_report in $str # let's access the pick_location inside the refill_report hash my $refill = $str->{refill_report}; my $pick_aref = $refill->{pick_location}; for my $pick (@$pick_aref) { # now we have one hashref in $pick print $pick->{pickid}, "\n"; } # let's try sorting # $a is an element of @$pick_aref; so it is a hashref my @sorted = sort { $a->{inv} <=> $b->{inv} } @$pick_aref; print Dumper($_) for @sorted; }

It's not a bad idea to postfix your intermediate variables with _href or _aref (like I did for one variable) just to remember whether you are dealing with a hash reference or an array reference.

I hope this helps. I spent quite a while pondering on how to access a complex data structure that a module spat out for me, but that was quite a while ago.

Replies are listed 'Best First'.
Re^4: How to use a json string with nested array and nested hash elements?
by Anonymous Monk on Feb 04, 2013 at 23:02 UTC
    Thanks for the code samples! It's exactly what I needed.

    I'm looking at what aitap wrote and what you wrote and I see one difference:

    aitap & 7Stud: my @jsonarray = @{$decoded_json->{strarray}};

    Anonymous Monk: my $strarray = $decoded_json->{strarray};

    I am surprised by the use of a $variable (string) instead of an @variable (array). I expected to need the same variable as aitap and 7Stud mentioned. I will need to restudy the variables and references, it's been nearly 6 years since I last wrote programs.

    Thank all of you for the explanations and examples. You have been very helpful.

      They dereference the array copying it to a new variable. This gives easier syntax, but the array is copied which might have performance implications. (They are very slight since the array is only a single element in this case.) Mine should have perhaps been named $strarray_aref since it was still a reference.

      All the variables I was using were references, hence a scalar $variable which get dereferenced with @{ } or %{ } or ->

      One thing I forgot to mention that the outermost loop in my code sample is pretty useless since the array is only a single element. It could be replaced with my $str = $strarray->[0];

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1016942]
[ambrus]: "you are far more likely to be squished between two other dudes" => wait, really? aren't most planes, weighted by people traveling on it, so narrow that there are only two or three seats on each side of the one corridor, so only one third of the people ge
[ambrus]: t squished between two other people?
holli is about to take the first hit since a month and this weed is strong shit. Should my head explode, someone call 911.
[ambrus]: And even when I traveled on a big plane for a long flight, it had 3 seats, then corridor, then 4 seats, then corridor, then 3 seats, so less than half of the people sit between two other dudes.

How do I use this? | Other CB clients
Other Users?
Others imbibing at the Monastery: (10)
As of 2017-12-18 13:39 GMT
Find Nodes?
    Voting Booth?
    What programming language do you hate the most?

    Results (486 votes). Check out past polls.