---
name: "json"
section: "3tcl"
platform: "linux"
package: "tcllib"
version: "2.0+dfsg-4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/json"
---

# json(3tcl)

JSON parser

```

```

## NAME

json - JSON parser

## SYNOPSIS

package require **Tcl 8.5 9**

package require **json ?1.3.6?**

**::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}}
```

## 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 output 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
```