This question got stuck in mailman,
From: Kenneth Tilton <ktilton(a)franz.com>
To: cl-json-devel(a)common-lisp.net
Date: Wed, 19 May 2010 16:14:31 -0400
Subject: How to get a JS false from cl-json?
t changes to unquoted true nicely, how about something that becomes
false? I see there is a choice between null and false so we cannot
just do false all the time.
nice lib, btw.
kt
And the answer is:
There are 3 different encoders.
With the "streaming" encoder you have full control of the output.
The guessing encoder (default) tries to make a decent json
representation of a s-expression, it does not discriminate between
null and false.
The pretty new explicit encoder gives more control over the json
representation, using a keyword in the first position of a list:
(test explicit-encoder
(is (string= "true" (with-explicit-encoder
(encode-json-to-string '(:true))))
"True")
(is (string= "false"
(with-explicit-encoder
(encode-json-to-string '(:false))))
"False")
(is (string= "null"
(with-explicit-encoder
(encode-json-to-string '(:null))))
"False")
There is a convenience function json-bool to make the keyword represenation:
(test json-bool
(is (equal (json-bool t) '(:true)))
(is (equal (json-bool 1) '(:true)))
(is (equal (json-bool nil) '(:false))))
Also a related question is how to encode an empty list. As an empty
json object {}, empty json-list [] or as json-null? That can also be
handled with the explicit encoder.
Here is a sample how a complex json structure can be built (from
testencoder.lisp)
(sample-2-plists
`(:object
:method some-function
:id 1
:params (:list
(:json "{\"id\":\"barId\",\"name\":\"bar\"}")
(:true)
(:list (:object "name" a :id b))
(:list (:object
:name foo
:id foo-id))
)))
(correct-json "
{\"method\":\"someFunction\",
\"id\":1,\"params\":
[{\"id\":\"barId\",\"name\":\"bar\"},
true,
[{\"name\":\"a\",\"id\":\"b\"}],
[{\"name\":\"foo\",\"id\":\"fooId\"}]]}")
/Henrik Hjelte
