json(3tcl) JSON json(3tcl)
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NAME
json - JSON parser
SYNOPSIS
package require Tcl 8.4
package require json ?1.3.4?
::json::json2dict txt
::json::many-json2dict txt ?max?
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DESCRIPTION
The json package provides a simple Tcl-only library for parsing the
JSON http://www.json.org/ data exchange format as specified in RFC 4627
http://www.ietf.org/rfc/rfc4627.txt. There is some ambiguity in pars-
ing JSON because JSON has type information that is not maintained by
the Tcl conversion. The json package returns data as a Tcl dict. Ei-
ther the dict package or Tcl 8.5 is required for use.
COMMANDS
::json::json2dict txt
Parse JSON formatted text txt into a Tcl dict and return the
value.
If txt contains more than one JSON entity only the first one is
returned.
::json::many-json2dict txt ?max?
Parse JSON formatted text txt containing multiple JSON entities
into a list of dictionaries and return that list.
If max is specified exactly that many entities are extracted
from txt. By default the command will attempt to extract all,
without limits. A value of "max == 0" does not make sense and
will cause the command to throw an error.
EXAMPLES
An example of a JSON array converted to Tcl. A JSON array is returned
as a single item with multiple elements.
[
{
"precision": "zip",
"Latitude": 37.7668,
"Longitude": -122.3959,
"Address": "",
"City": "SAN FRANCISCO",
"State": "CA",
"Zip": "94107",
"Country": "US"
},
{
"precision": "zip",
"Latitude": 37.371991,
"Longitude": -122.026020,
"Address": "",
"City": "SUNNYVALE",
"State": "CA",
"Zip": "94085",
"Country": "US"
}
]
=>
{Country US Latitude 37.7668 precision zip State CA City {SAN FRANCISCO} Address {} Zip 94107 Longitude -122.3959} {Country US Latitude 37.371991 precision zip State CA City SUNNYVALE Address {} Zip 94085 Longitude -122.026020}
An example of a JSON object converted to Tcl. A JSON object is re-
turned as a multi-element list (a dict).
{
"Image": {
"Width": 800,
"Height": 600,
"Title": "View from 15th Floor",
"Thumbnail": {
"Url": "http://www.example.com/image/481989943",
"Height": 125,
"Width": "100"
},
"IDs": [116, 943, 234, 38793]
}
}
=>
Image {IDs {116 943 234 38793} Thumbnail {Width 100 Height 125 Url http://www.example.com/image/481989943} Width 800 Height 600 Title {View from 15th Floor}}
RELATED
To write json, instead of parsing it, see package json::write.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain
bugs and other problems. Please report such in the category json of
the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
also report any ideas for enhancements you may have for either package
and/or documentation.
When proposing code changes, please provide unified diffs, i.e the out-
put of diff -u.
Note further that attachments are strongly preferred over inlined
patches. Attachments can be made by going to the Edit form of the
ticket immediately after its creation, and then using the left-most
button in the secondary navigation bar.
KEYWORDS
data exchange, exchange format, javascript, json
CATEGORY
CGI programming
COPYRIGHT
Copyright (c) 2006 ActiveState Software Inc.
Copyright (c) 2009 Thomas Maeder, Glue Software Engineering AG
tcllib 1.3.4 json(3tcl)