… | |
… | |
467 | |
467 | |
468 | =item $json = $json->allow_blessed ([$enable]) |
468 | =item $json = $json->allow_blessed ([$enable]) |
469 | |
469 | |
470 | =item $enabled = $json->get_allow_blessed |
470 | =item $enabled = $json->get_allow_blessed |
471 | |
471 | |
|
|
472 | See L<OBJECT SERIALISATION> for details. |
|
|
473 | |
472 | If C<$enable> is true (or missing), then the C<encode> method will not |
474 | If C<$enable> is true (or missing), then the C<encode> method will not |
473 | barf when it encounters a blessed reference. Instead, the value of the |
475 | barf when it encounters a blessed reference that it cannot convert |
474 | B<convert_blessed> option will decide whether C<null> (C<convert_blessed> |
476 | otherwise. Instead, a JSON C<null> value is encoded instead of the object. |
475 | disabled or no C<TO_JSON> method found) or a representation of the |
|
|
476 | object (C<convert_blessed> enabled and C<TO_JSON> method found) is being |
|
|
477 | encoded. Has no effect on C<decode>. |
|
|
478 | |
477 | |
479 | If C<$enable> is false (the default), then C<encode> will throw an |
478 | If C<$enable> is false (the default), then C<encode> will throw an |
480 | exception when it encounters a blessed object. |
479 | exception when it encounters a blessed object that it cannot convert |
|
|
480 | otherwise. |
|
|
481 | |
|
|
482 | This setting has no effect on C<decode>. |
481 | |
483 | |
482 | =item $json = $json->convert_blessed ([$enable]) |
484 | =item $json = $json->convert_blessed ([$enable]) |
483 | |
485 | |
484 | =item $enabled = $json->get_convert_blessed |
486 | =item $enabled = $json->get_convert_blessed |
|
|
487 | |
|
|
488 | See L<OBJECT SERIALISATION> for details. |
485 | |
489 | |
486 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
490 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
487 | blessed object, will check for the availability of the C<TO_JSON> method |
491 | blessed object, will check for the availability of the C<TO_JSON> method |
488 | on the object's class. If found, it will be called in scalar context |
492 | on the object's class. If found, it will be called in scalar context and |
489 | and the resulting scalar will be encoded instead of the object. If no |
493 | the resulting scalar will be encoded instead of the object. |
490 | C<TO_JSON> method is found, the value of C<allow_blessed> will decide what |
|
|
491 | to do. |
|
|
492 | |
494 | |
493 | The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> |
495 | The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> |
494 | returns other blessed objects, those will be handled in the same |
496 | returns other blessed objects, those will be handled in the same |
495 | way. C<TO_JSON> must take care of not causing an endless recursion cycle |
497 | way. C<TO_JSON> must take care of not causing an endless recursion cycle |
496 | (== crash) in this case. The name of C<TO_JSON> was chosen because other |
498 | (== crash) in this case. The name of C<TO_JSON> was chosen because other |
497 | methods called by the Perl core (== not by the user of the object) are |
499 | methods called by the Perl core (== not by the user of the object) are |
498 | usually in upper case letters and to avoid collisions with any C<to_json> |
500 | usually in upper case letters and to avoid collisions with any C<to_json> |
499 | function or method. |
501 | function or method. |
500 | |
502 | |
501 | This setting does not yet influence C<decode> in any way, but in the |
503 | If C<$enable> is false (the default), then C<encode> will not consider |
502 | future, global hooks might get installed that influence C<decode> and are |
504 | this type of conversion. |
503 | enabled by this setting. |
|
|
504 | |
505 | |
505 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
506 | This setting has no effect on C<decode>. |
506 | to do when a blessed object is found. |
507 | |
|
|
508 | =item $json = $json->allow_tags ([$enable]) |
|
|
509 | |
|
|
510 | =item $enabled = $json->allow_tags |
|
|
511 | |
|
|
512 | See L<OBJECT SERIALISATION> for details. |
|
|
513 | |
|
|
514 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
|
|
515 | blessed object, will check for the availability of the C<FREEZE> method on |
|
|
516 | the object's class. If found, it will be used to serialise the object into |
|
|
517 | a nonstandard tagged JSON value (that JSON decoders cannot decode). |
|
|
518 | |
|
|
519 | It also causes C<decode> to parse such tagged JSON values and deserialise |
|
|
520 | them via a call to the C<THAW> method. |
|
|
521 | |
|
|
522 | If C<$enable> is false (the default), then C<encode> will not consider |
|
|
523 | this type of conversion, and tagged JSON values will cause a parse error |
|
|
524 | in C<decode>, as if tags were not part of the grammar. |
507 | |
525 | |
508 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) |
526 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) |
509 | |
527 | |
510 | When C<$coderef> is specified, it will be called from C<decode> each |
528 | When C<$coderef> is specified, it will be called from C<decode> each |
511 | time it decodes a JSON object. The only argument is a reference to the |
529 | time it decodes a JSON object. The only argument is a reference to the |
… | |
… | |
999 | Another nonstandard extension to the JSON syntax, enabled with the |
1017 | Another nonstandard extension to the JSON syntax, enabled with the |
1000 | C<allow_tags> setting, are tagged values. In this implementation, the |
1018 | C<allow_tags> setting, are tagged values. In this implementation, the |
1001 | I<tag> must be a perl package/class name encoded as a JSON string, and the |
1019 | I<tag> must be a perl package/class name encoded as a JSON string, and the |
1002 | I<value> must be a JSON array encoding optional constructor arguments. |
1020 | I<value> must be a JSON array encoding optional constructor arguments. |
1003 | |
1021 | |
1004 | See "OBJECT SERIALISATION", below, for details. |
1022 | See L<OBJECT SERIALISATION>, below, for details. |
1005 | |
1023 | |
1006 | =back |
1024 | =back |
1007 | |
1025 | |
1008 | |
1026 | |
1009 | =head2 PERL -> JSON |
1027 | =head2 PERL -> JSON |
… | |
… | |
1048 | directly if you want. |
1066 | directly if you want. |
1049 | |
1067 | |
1050 | =item blessed objects |
1068 | =item blessed objects |
1051 | |
1069 | |
1052 | Blessed objects are not directly representable in JSON, but C<JSON::XS> |
1070 | Blessed objects are not directly representable in JSON, but C<JSON::XS> |
1053 | allows various ways of handling objects. See "OBJECT SERIALISATION", |
1071 | allows various ways of handling objects. See L<OBJECT SERIALISATION>, |
1054 | below, for details. |
1072 | below, for details. |
1055 | |
1073 | |
1056 | =item simple scalars |
1074 | =item simple scalars |
1057 | |
1075 | |
1058 | Simple Perl scalars (any scalar that is not a reference) are the most |
1076 | Simple Perl scalars (any scalar that is not a reference) are the most |
… | |
… | |
1111 | C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are |
1129 | C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are |
1112 | used in this order: |
1130 | used in this order: |
1113 | |
1131 | |
1114 | =over 4 |
1132 | =over 4 |
1115 | |
1133 | |
1116 | =item 1. C<allow_tags> is enabled and object has a C<FREEZE> method. |
1134 | =item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method. |
1117 | |
1135 | |
1118 | In this case, C<JSON::XS> uses the L<Types::Serialiser> object |
1136 | In this case, C<JSON::XS> uses the L<Types::Serialiser> object |
1119 | serialisation protocol to create a tagged JSON value, using a nonstandard |
1137 | serialisation protocol to create a tagged JSON value, using a nonstandard |
1120 | extension to the JSON syntax. |
1138 | extension to the JSON syntax. |
1121 | |
1139 | |
… | |
… | |
1127 | more). These values and the paclkage/classname of the object will then be |
1145 | more). These values and the paclkage/classname of the object will then be |
1128 | encoded as a tagged JSON value in the following format: |
1146 | encoded as a tagged JSON value in the following format: |
1129 | |
1147 | |
1130 | ("classname")[FREEZE return values...] |
1148 | ("classname")[FREEZE return values...] |
1131 | |
1149 | |
|
|
1150 | e.g.: |
|
|
1151 | |
|
|
1152 | ("URI")["http://www.google.com/"] |
|
|
1153 | ("MyDate")[2013,10,29] |
|
|
1154 | ("ImageData::JPEG")["Z3...VlCg=="] |
|
|
1155 | |
1132 | For example, the hypothetical C<My::Object> C<FREEZE> method might use the |
1156 | For example, the hypothetical C<My::Object> C<FREEZE> method might use the |
1133 | objects C<type> and C<id> members to encode the object: |
1157 | objects C<type> and C<id> members to encode the object: |
1134 | |
1158 | |
1135 | sub My::Object::FREEZE { |
1159 | sub My::Object::FREEZE { |
1136 | my ($self, $serialiser) = @_; |
1160 | my ($self, $serialiser) = @_; |
1137 | |
1161 | |
1138 | ($self->{type}, $self->{id}) |
1162 | ($self->{type}, $self->{id}) |
1139 | } |
1163 | } |
1140 | |
1164 | |
1141 | =item 2. C<convert_blessed> is enabled and object has a C<TO_JSON> method. |
1165 | =item 2. C<convert_blessed> is enabled and the object has a C<TO_JSON> method. |
1142 | |
1166 | |
1143 | In this case, the C<TO_JSON> method of the object is invoked in scalar |
1167 | In this case, the C<TO_JSON> method of the object is invoked in scalar |
1144 | context. It must return a single scalar that can be directly encoded into |
1168 | context. It must return a single scalar that can be directly encoded into |
1145 | JSON. This scalar replaces the object in the JSON text. |
1169 | JSON. This scalar replaces the object in the JSON text. |
1146 | |
1170 | |
… | |
… | |
1176 | This section only considers the tagged value case: I a tagged JSON object |
1200 | This section only considers the tagged value case: I a tagged JSON object |
1177 | is encountered during decoding and C<allow_tags> is disabled, a parse |
1201 | is encountered during decoding and C<allow_tags> is disabled, a parse |
1178 | error will result (as if tagged values were not part of the grammar). |
1202 | error will result (as if tagged values were not part of the grammar). |
1179 | |
1203 | |
1180 | If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method |
1204 | If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method |
1181 | of the package/classname used during serialisation. If there is no such |
1205 | of the package/classname used during serialisation (it will not attempt |
|
|
1206 | to load the package as a Perl module). If there is no such method, the |
1182 | method, the decoding will fail with an error. |
1207 | decoding will fail with an error. |
1183 | |
1208 | |
1184 | Otherwise, the C<THAW> method is invoked with the classname as first |
1209 | Otherwise, the C<THAW> method is invoked with the classname as first |
1185 | argument, the constant string C<JSON> as second argument, and all the |
1210 | argument, the constant string C<JSON> as second argument, and all the |
1186 | values from the JSON array (the values originally returned by the |
1211 | values from the JSON array (the values originally returned by the |
1187 | C<FREEZE> method) as remaining arguments. |
1212 | C<FREEZE> method) as remaining arguments. |