json man page

json — JSON parser

Synopsis

package require Tcl 8.4

package require json ?1.3.3?

::json::json2dict txt

::json::many-json2dict txt ?max?

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 parsing JSON because JSON has type information that is not maintained by the Tcl conversion. The json package returns data as a Tcl dict. Either 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 returned 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}}

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.

Keywords

data exchange, exchange format, javascript, json

Category

CGI programming

Info

1.3.3 tcllib JSON