| … | |
… | |
| 347 | future, global hooks might get installed that influence C<decode> and are |
347 | future, global hooks might get installed that influence C<decode> and are |
| 348 | enabled by this setting. |
348 | enabled by this setting. |
| 349 | |
349 | |
| 350 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
350 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
| 351 | to do when a blessed object is found. |
351 | to do when a blessed object is found. |
|
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352 | |
|
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353 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) |
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354 | |
|
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355 | When C<$coderef> is specified, it will be called from C<decode> each |
|
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356 | time it decodes a JSON object. The only argument is a reference to the |
|
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357 | newly-created hash. If the code references returns a single scalar (which |
|
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358 | need not be a reference), this value (i.e. a copy of that scalar to avoid |
|
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359 | aliasing) is inserted into the deserialised data structure. If it returns |
|
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360 | an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the |
|
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361 | original deserialised hash will be inserted. This setting can slow down |
|
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362 | decoding considerably. |
|
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363 | |
|
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364 | When C<$coderef> is omitted or undefined, any existing callback will |
|
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365 | be removed and C<decode> will not change the deserialised hash in any |
|
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366 | way. |
|
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367 | |
|
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368 | Example, convert all JSON objects into the integer 5: |
|
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369 | |
|
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370 | my $js = JSON::XS->new->filter_json_object (sub { 5 }); |
|
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371 | # returns [5] |
|
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372 | $js->decode ('[{}]') |
|
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373 | # throw an exception because allow_nonref is not enabled |
|
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374 | # so a lone 5 is not allowed. |
|
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375 | $js->decode ('{"a":1, "b":2}'); |
|
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376 | |
|
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377 | =item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)]) |
|
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378 | |
|
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379 | Works remotely similar to C<filter_json_object>, but is only called for |
|
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380 | JSON objects having a single key named C<$key>. |
|
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381 | |
|
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382 | This C<$coderef> is called before the one specified via |
|
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383 | C<filter_json_object>, if any. It gets passed the single value in the JSON |
|
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384 | object. If it returns a single value, it will be inserted into the data |
|
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385 | structure. If it returns nothing (not even C<undef> but the empty list), |
|
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386 | the callback from C<filter_json_object> will be called next, as if no |
|
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387 | single-key callback were specified. |
|
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388 | |
|
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389 | If C<$coderef> is omitted or undefined, the corresponding callback will be |
|
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390 | disabled. There can only ever be one callback for a given key. |
|
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391 | |
|
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392 | As this callback gets called less often then the C<filter_json_object> |
|
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393 | one, decoding speed will not usually suffer as much. Therefore, single-key |
|
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394 | objects make excellent targets to serialise Perl objects into, especially |
|
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395 | as single-key JSON objects are as close to the type-tagged value concept |
|
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396 | as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not |
|
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397 | support this in any way, so you need to make sure your data never looks |
|
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398 | like a serialised Perl hash. |
|
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399 | |
|
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400 | Typical names for the single object key are C<__class_whatever__>, or |
|
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401 | C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even |
|
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402 | things like C<__class_md5sum(classname)__>, to reduce the risk of clashing |
|
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403 | with real hashes. |
|
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404 | |
|
|
405 | Example, decode JSON objects of the form C<< { "__widget__" => <id> } >> |
|
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406 | into the corresponding C<< $WIDGET{<id>} >> object: |
|
|
407 | |
|
|
408 | # return whatever is in $WIDGET{5}: |
|
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409 | JSON::XS |
|
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410 | ->new |
|
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411 | ->filter_json_single_key_object (__widget__ => sub { |
|
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412 | $WIDGET{ $_[0] } |
|
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413 | }) |
|
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414 | ->decode ('{"__widget__": 5') |
|
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415 | |
|
|
416 | # this can be used with a TO_JSON method in some "widget" class |
|
|
417 | # for serialisation to json: |
|
|
418 | sub WidgetBase::TO_JSON { |
|
|
419 | my ($self) = @_; |
|
|
420 | |
|
|
421 | unless ($self->{id}) { |
|
|
422 | $self->{id} = ..get..some..id..; |
|
|
423 | $WIDGET{$self->{id}} = $self; |
|
|
424 | } |
|
|
425 | |
|
|
426 | { __widget__ => $self->{id} } |
|
|
427 | } |
| 352 | |
428 | |
| 353 | =item $json = $json->shrink ([$enable]) |
429 | =item $json = $json->shrink ([$enable]) |
| 354 | |
430 | |
| 355 | Perl usually over-allocates memory a bit when allocating space for |
431 | Perl usually over-allocates memory a bit when allocating space for |
| 356 | strings. This flag optionally resizes strings generated by either |
432 | strings. This flag optionally resizes strings generated by either |
| … | |
… | |
| 802 | still relatively early in its development. If you keep reporting bugs they |
878 | still relatively early in its development. If you keep reporting bugs they |
| 803 | will be fixed swiftly, though. |
879 | will be fixed swiftly, though. |
| 804 | |
880 | |
| 805 | =cut |
881 | =cut |
| 806 | |
882 | |
| 807 | our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; |
883 | our $true = do { bless \(my $dummy = "1"), "JSON::XS::Boolean" }; |
| 808 | our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; |
884 | our $false = do { bless \(my $dummy = "0"), "JSON::XS::Boolean" }; |
| 809 | |
885 | |
| 810 | sub true() { $true } |
886 | sub true() { $true } |
| 811 | sub false() { $false } |
887 | sub false() { $false } |
| 812 | |
888 | |
| 813 | sub is_bool($) { |
889 | sub is_bool($) { |
