data.json
JSON parser/generator to/from Clojure data structures.
Key goals:
- Compliant with JSON spec per https://json.org/
- No external dependencies
Releases and Dependency Information
This project follows the version scheme MAJOR.MINOR.PATCH where each component provides some relative indication of the size of the change, but does not follow semantic versioning. In general, all changes endeavor to be non-breaking (by moving to new names rather than by breaking existing names).
Latest stable release is 2.4.0
CLI/deps.edn
dependency information:
org.clojure/data.json {:mvn/version "2.4.0"}
Leiningen dependency information:
[org.clojure/data.json "2.4.0"]
Maven dependency information:
<dependency>
<groupId>org.clojure</groupId>
<artifactId>data.json</artifactId>
<version>2.4.0</version>
</dependency>
Other versions:
Usage
Example usage:
(ns example
(:require [clojure.data.json :as json]))
To convert to/from JSON strings, use json/write-str
and json/read-str
:
(json/write-str {:a 1 :b 2})
;;=> "{\"a\":1,\"b\":2}"
(json/read-str "{\"a\":1,\"b\":2}")
;;=> {"a" 1, "b" 2}
Note that these operations are not symmetric: converting Clojure data into JSON is lossy.
Converting Key/Value Types
You can specify a :key-fn
to convert map keys on the way in or out:
(json/read-str "{\"a\":1,\"b\":2}"
:key-fn keyword)
;;=> {:a 1, :b 2}
(json/write-str {:a 1 :b 2}
:key-fn #(.toUpperCase %))
;;=> "{\"A\":1,\"B\":2}"
(json/read-str "{\"a\":1,\"b\":2}"
:key-fn #(keyword "com.example" %))
;;=> {:com.example/a 1, :com.example/b 2}
You can specify a :value-fn
to convert map values on the way in or
out. The value-fn will be called with two arguments, the key and the
value, and it returns the updated value.
(defn my-value-reader [key value]
(if (= key :date)
(java.sql.Date/valueOf value)
value))
(json/read-str "{\"number\":42,\"date\":\"2012-06-02\"}"
:value-fn my-value-reader
:key-fn keyword)
;;=> {:number 42, :date #inst "2012-06-02T04:00:00.000-00:00"}
Be aware that :value-fn
only works on maps (JSON objects). If your
root data structure is, for example, a vector of dates, you will need
to pre- or post-process it outside of data.json. clojure.walk may be
useful for this.
Order of key-fn / value-fn
If you specify both a :key-fn
and a :value-fn
when reading,
the value-fn is called after the key has been processed by the
key-fn.
The reverse is true when writing:
(defn my-value-writer [key value]
(if (= key :date)
(str (java.sql.Date. (.getTime value)))
value))
(json/write-str {:number 42, :date (java.util.Date. 112 5 2)}
:value-fn my-value-writer
:key-fn name)
;;=> "{\"number\":42,\"date\":\"2012-06-02\"}"
Reading/Writing a Stream
You can also read JSON directly from a java.io.Reader with json/read
and write JSON directly to a java.io.Writer with json/write
.
More
Other options are available. Refer to the API Documentation for details.
Developer Information
Change Log
- Release 2.4.0 on 2021-Jul-12
- Release 2.3.1 on 2021-May-19
- Fix DJSON-51: Fix possible read of x00's in quoted strings on partial stream read
- Release 2.3.0 on 2021-May-14
- Release 2.2.3 on 2021-May-6
- Fix DJSON-47: Make number parsing match spec (reject invalid numbers)
- Release 2.2.2 on 2021-Apr-26
- Release 2.2.1 on 2021-Apr-19
- Revert DJSON-36: Problem with transient batching in that change
- Release 2.2.0 on 2021-Apr-16
- Add DJSON-41: New support for writing java.time.Instant and java.util.Date (+ subclasses)
- New options to
write
functions::date-formatter
-java.time.DateTimeFormatter
to use (defaultDateTimeFormatter/ISO_INSTANT
):sql-date-converter
- fn to convertjava.sql.Date
tojava.time.Instant
(default provided)
- New options to
- Perf DJSON-36: Refactor code in read-array and read-object
- Add DJSON-41: New support for writing java.time.Instant and java.util.Date (+ subclasses)
- Release 2.1.1 on 2021-Apr-15
- Fix DJSON-43: Fix buffer overflow in pushbackreader
- Update parent pom to latest (1.1.0)
- Release 2.1.0 on 2021-Apr-6
- Fix DJSON-39: Support writing UUIDs (as strings)
- Release 2.0.2 on 2021-Mar-27
- Release 2.0.1 on 2021-Mar-19
- Fix DJSON-37: Fix off-by-one error reading long strings, regression in 2.0.0
- Release 2.0.0 on 2021-Mar-19
- Release 1.1.0 on 2021-Mar-5
- Fix DJSON-26: write-object should check seq on loop var, not param
- Use latest parent pom (will bump default clojure dep to 1.8.0)
- Use direct linking on "aot" classifier lib
- Release 1.0.0 on 2020-Feb-18
- Release 0.2.7 on 2019-Nov-18
- Fix DJSON-29: throw exception on missing object entries (extra commas)
- Release 0.2.6 on 2015-Mar-6
- Modify build to produce an AOT package with classifier "aot"
- Release 0.2.5 on 2014-Jun-13
- Fix DJSON-17: throw exception on Infinite or NaN floating-point values. Old behavior could produce invalid JSON.
- Release 0.2.4 on 2014-Jan-10
- Release 0.2.3 on 2013-Aug-30
- Release 0.2.2 on 2013-Apr-07
- Release 0.2.1 on 2012-Oct-26
- Restores backwards-compatibility with 0.1.x releases. The older 0.1.x APIs are marked as deprecated in their documentation. They will be removed in a future release.
- Release 0.2.0 on 2012-Oct-12
- Not recommended for use: this release introduced breaking API changes (renaming core functions) without any path for backwards-compatibility. Applications with transitive dependencies on both the 0.2.x and 0.1.x APIs cannot use this version.
- New :key-fn and :value-fn permit flexible transformation of values when reading & writing JSON
- Support for reading large integers as BigInt
- Optional support for reading decimals as BigDecimal
- Performance improvements
- Release 0.1.3 on 2012-Mar-09
- Fix writing strings containing characters outside the BMP
- Release 0.1.2 on 2011-Oct-14
- Better parsing of hexadecimal character escapes
- Fix EOF-handling bug
- Fix DJSON-1: reflection warnings
- Release 0.1.1 on 2011-Jul-01
- Ensure that printing to
*out*
always uses a PrintWriter.
- Ensure that printing to
- Release 0.1.0 on 2011-Mar-18
- Initial release.
- Source-compatible with clojure.contrib.json, except for the name change.
Copyright and License
Copyright (c) Stuart Sierra, Rich Hickey, and contriburos 2012-2020. All rights reserved. The use and distribution terms for this software are covered by the Eclipse Public License 1.0 (https://opensource.org/licenses/eclipse-1.0.php) which can be found in the file epl-v10.html at the root of this distribution. By using this software in any fashion, you are agreeing to be bound by the terms of this license. You must not remove this notice, or any other, from this software.