Perl Requires Chilkat v9.5.0.67+

Using Pre-defined JSON Templates

See more JSON Examples

Demonstrates how to predefine a JSON template, and then use it to emit JSON with variable substitutions. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# One way to create JSON is to do it in a straightforward manner:
my $json = Chilkat2::JsonObject->new;
$json->EmitCompact(0);
$json->UpdateString('id', '0001');
$json->UpdateString('type', 'donut');
$json->UpdateString('name', 'Cake');
$json->UpdateString('image.url', 'images/0001.jpg');
$json->UpdateInt('image.width', 200);
$json->UpdateInt('image.height', 200);
$json->UpdateString('thumbnail.url', 'images/thumbnails/0001.jpg');
$json->UpdateInt('thumbnail.width', 32);
$json->UpdateInt('thumbnail.height', 32);
print $json->Emit(), "\n";

# The JSON created by the above code:

#     {
#       "id": "0001",
#       "type": "donut",
#       "name": "Cake",
#       "image": {
#         "url": "images/0001.jpg",
#         "width": 200,
#         "height": 200
#       },
#       "thumbnail": {
#         "url": "images/thumbnails/0001.jpg",
#         "width": 32,
#         "height": 32
#       }
#     }

# An alternative is to predefine a template, and then use it to emit with variable substitutions.
# For example:

my $jsonTemplate = Chilkat2::JsonObject->new;
$jsonTemplate->UpdateString('id', '{$id}');
$jsonTemplate->UpdateString('type', 'donut');
$jsonTemplate->UpdateString('name', '{$name}');
$jsonTemplate->UpdateString('image.url', '{$imageUrl}');
# The "i." indicates that it's an integer variable.
$jsonTemplate->UpdateString('image.width', '{$i.imageWidth}');
$jsonTemplate->UpdateString('image.height', '{$i.imageHeight}');
$jsonTemplate->UpdateString('thumbnail.url', '{$thumbUrl}');
$jsonTemplate->UpdateString('thumbnail.width', '{$i.thumbWidth}');
$jsonTemplate->UpdateString('thumbnail.height', '{$i.thumbHeight}');
# Give this template a name.
$jsonTemplate->Predefine('donut');

# --------------------------------------------------------------------------
# OK, the template is defined.  Defining a template can be done once
# at the start of your program, and you can discard the jsonTemplate object (it
# doesn't need to stick around..)

# Now we can create instances of the JSON object by name:
my $jsonDonut = Chilkat2::JsonObject->new;
$jsonDonut->EmitCompact(0);
$jsonDonut->LoadPredefined('donut');
print $jsonDonut->Emit(), "\n";

# The output is this:

#     {
#       "id": "{$id}",
#       "type": "donut",
#       "name": "{$name}",
#       "image": {
#         "url": "{$imageUrl}",
#         "width": "{$i.imageWidth}",
#         "height": "{$i.imageHeight}"
#       },
#       "thumbnail": {
#         "url": "{$thumbUrl}",
#         "width": "{$i.thumbWidth}",
#         "height": "{$i.thumbHeight}"
#       }
#     }

# Finally, we can substitute variables like this:
my $donutValues = Chilkat2::Hashtable->new;
$donutValues->AddStr('id', '0001');
$donutValues->AddStr('name', 'Cake');
$donutValues->AddStr('imageUrl', 'images/0001.jpg');
$donutValues->AddInt('imageWidth', 200);
$donutValues->AddInt('imageHeight', 200);
$donutValues->AddStr('thumbUrl', 'images/thumbnails/0001.jpg');
$donutValues->AddInt('thumbWidth', 32);
$donutValues->AddInt('thumbHeight', 32);

# Emit with variable substitutions:
my $omitEmpty = 1;
print $jsonDonut->EmitWithSubs($donutValues, $omitEmpty), "\n";

# Output:

#     {
#       "id": "0001",
#       "type": "donut",
#       "name": "Cake",
#       "image": {
#         "url": "images/0001.jpg",
#         "width": 200,
#         "height": 200
#       },
#       "thumbnail": {
#         "url": "images/thumbnails/0001.jpg",
#         "width": 32,
#         "height": 32
#       }
#     }

# Change some of the values:
$donutValues->AddStr('id', '0002');
$donutValues->AddStr('imageUrl', 'images/0002.jpg');
$donutValues->AddStr('thumbUrl', 'images/thumbnails/0002.jpg');

print $jsonDonut->EmitWithSubs($donutValues, $omitEmpty), "\n";

# Output:

#     {
#       "id": "0002",
#       "type": "donut",
#       "name": "Cake",
#       "image": {
#         "url": "images/0002.jpg",
#         "width": 200,
#         "height": 200
#       },
#       "thumbnail": {
#         "url": "images/thumbnails/0002.jpg",
#         "width": 32,
#         "height": 32
#       }
#     }