json decode transforms empty objects to empty strings

[einar-hjortdal]

Describe the bug

module main

import json

const hypothetical_json = "{\"propertyOne\":\"property_two should be parsed as a string representing an empty object {}\",\"propertyTwo\":{},\"property_three\":{\"nestedOne\":\"\"},\"propertyFour\":{}}"

struct TestStructOne {
	property_one string [json: 'propertyOne']
	property_two string [json: 'propertyTwo']
	property_three TestStructTwo [json: 'property_three']
	property_four TestStructTwo [json: 'propertyFour']
}

struct TestStructTwo {
	nested_one string [json: 'nestedOne']
}

fn main() {
	// suppose TestStructOne is received as request body from a JSON API or frontend framework
	// suppose property_two expects an arbitrary object, stringified with JSON.stringify
	// JSON.stringify outputs {} to represent an empty object
	// json.decode parses {} as ''
	// An empty string in JSON is "", not {}
println(json.decode(TestStructOne, hypothetical_json)!)
}

Reproduction Steps

Run the code above

Expected Behavior

{} should be parsed as '{}'

Current Behavior

{} is parsed as ""

Possible Solution

No response

Additional Information/Context

No response

V version

Current V version: V 0.4.2 a92700e, timestamp: 2023-11-06 20:09:05 +0200

Environment details (OS name and version, etc.)

V full version: V 0.4.2 95509cf.a92700e
OS: linux, Linux version 5.14.0-284.30.1.el9_2.x86_64 (mockbuild@mj.euro.kojibuilder106) (gcc (GCC) 11.3.1 20221121 (Red Hat 11.3.1-4), GNU ld version 2.35.2-37.el9) #1 SMP PREEMPT_DYNAMIC Fri Sep 15 08:06:33 UTC 2023
Processor: 8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz

getwd: /home/coachonko
vexe: /home/coachonko/.local/lib64/v/v
vexe mtime: 2023-11-06 21:32:00

vroot: OK, value: /home/coachonko/.local/lib64/v
VMODULES: OK, value: /home/coachonko/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.39.3
Git vroot status: weekly.2023.43-126-ga92700e9
.git/config present: true

CC version: cc (GCC) 11.3.1 20221121 (Red Hat 11.3.1-4)
thirdparty/tcc status: thirdparty-linux-amd64 12f392c3

[einar-hjortdal]

Maybe not a bug but expected.

An empty map is represented by {}, but anything else is also turned to {}

struct Any {}
struct TestStructThree {
	prop_one map[string]Any [json: 'propOne']
}
fn main() {
	test_struct := TestStructThree{}
	println(json.encode(test_struct)) // {"propOne":{}}
	println(json.decode(TestStructThree, '{"propertyOne":{}}')!)
	//TestStructThree{
	//	prop_one: {}
	//}
// Hoever
test := json.decode(TestStructThree, '\"{\"propertyOne\":\"should be parsed as a string\"}\"')!
println(test) // also results as empty object

test_two := json.decode(TestStructThree, '"{\n  \"topLevelProperty\": {\n    \"nestedProperty1\": \"Value 1\",\n    \"nestedProperty2\": \"Value 2\",\n    \"nestedProperty3\": {\n      \"subNestedProperty1\": \"Sub-Value 1\",\n      \"subNestedProperty2\": \"Sub-Value 2\"\n    }\n  }\n}"')!
println(test_two) // also results as empty object
}

I believe:

1. {} should fail to be decoded to string.
2. There should be a type that accepts raw json such that it can be passed through V to a database

[einar-hjortdal]

Searched the source code: json [raw] attribute exists but is not documented.
This issue needs relabeling. It's a documentation issue now