toJSON incorrectly stringifies object

[Grafu]

Describe the bug

When serializing a standalone object, the returned JSON puts it into an array. This is incorrect because the object is not in an array before serialization. An argument for correct behavior should solve the problem.

To reproduce

srun outputChatBox(toJSON ( { "dogs", cat = "hungry", mouse = "food", birds = 4 } ))

Expected behaviour

Command results: { "1": "dogs", "mouse": "food", "cat": "hungry", "birds": 4 } [string]

Actual behaviour

Command results: [ { "1": "dogs", "mouse": "food", "cat": "hungry", "birds": 4 } ] [string]

This should only be triggered by:
toJSON ( { { "dogs", cat = "hungry", mouse = "food", birds = 4 } } )

Version

MTA:SA Server v1.5.6-release-16345
Multi Theft Auto v1.5.6-release-18706

[patrikjuvonen]

Indeed we need a new argument for this correct behavior.

[dmi7ry]

Also I would like to have abillity to disable json optimisation

[qaisjp]

JSON optimisation?

[dmi7ry]

If there are same tables, toJSON() may store them as links on the first table, it looks like ... ,"^T^9","^T^9","^T^9", ... ,"^T^15" etc.

[qaisjp]

If there are same tables, toJSON() may store them as links on the first table, it looks like ... ,"^T^9","^T^9","^T^9", ... ,"^T^15" etc.

This seems like a bug and should only happen for self-referencing tables. Please can you create a separate issue for this?

i.e. this should not happen:

run a = { this = "that" }
run toJSON({ alpha = a, beta = a })
[16:19:52] Command results: [ { "alpha": { "this": "that" }, "beta": "^T^1" } ] [string]

Relevant: e883f1c

mtasa-blue/Server/mods/deathmatch/logic/lua/CLuaArgument.cpp

Lines 811 to 825 in e11685c

	case LUA_TTABLE:
	{
	ulong* pTableId;
	if (pKnownTables && (pTableId = MapFind(*pKnownTables, m_pTableData)))
	{
	// Self-referencing table
	char szTableID[10];
	snprintf(szTableID, sizeof(szTableID), "^T^%lu", *pTableId);
	return json_object_new_string(szTableID);
	}
	else
	{
	return m_pTableData->WriteTableToJSONObject(bSerialize, pKnownTables);
	}
	}

(and the corresponding client file).

[dmi7ry]

I'm exactly about self-referencing tables.
So it would be useful, for example, if I need later edit the result by hands (in DB), or work with it on web, etc.

[qaisjp]

It is not possible to represent self-referencing tables in JSON

[dmi7ry]

I want it just writes a copy of the table instead of the link to it. Something like this:

run a = { this = "that" }
run toJSON({ alpha = a, beta = a }, true, "none", true ) -- last `true` to diable references on tables
[16:19:52] Command results: [ { "alpha": { "this": "that" }, "beta": { "this": "that" } } ] [string]

[patrikjuvonen]

But how would a copy work? It's an infinite loop or I'm missing something?

Nevermind. Seems like something we should add an option for.

I propose we change toJSON to accept an options table with the current option arguments and add a new one named maybe useReferencing (?) (default: true).

[qaisjp]

I actually think it's a bug and only meant to be for truly self-referencing (recursive) tables — in this case I think we should fix the ^T happening without any args.

[Pirulax]

No shit, so thats what is causing MTA's famous double array JSON.. I see..
FYI the whole CLuaArgument class is bad as a whole.
I wanted to refactor it, but i got brain damage.

[Disinterpreter]

I made a small "investigation" and found the problem in json-c library

Just look at 1387 and 1417-1418

mtasa-blue/vendor/json-c/json_object.c

Lines 1381 to 1419 in 83ca27a

	static int json_object_array_to_json_string(struct json_object *jso, struct printbuf *pb, int level,
	int flags)
	{
	int had_children = 0;
	size_t ii;
	printbuf_strappend(pb, "[");
	if (flags & JSON_C_TO_STRING_PRETTY)
	printbuf_strappend(pb, "\n");
	for (ii = 0; ii < json_object_array_length(jso); ii++)
	{
	struct json_object *val;
	if (had_children)
	{
	printbuf_strappend(pb, ",");
	if (flags & JSON_C_TO_STRING_PRETTY)
	printbuf_strappend(pb, "\n");
	}
	had_children = 1;
	if (flags & JSON_C_TO_STRING_SPACED && !(flags & JSON_C_TO_STRING_PRETTY))
	printbuf_strappend(pb, " ");
	indent(pb, level + 1, flags);
	val = json_object_array_get_idx(jso, ii);
	if (val == NULL)
	printbuf_strappend(pb, "null");
	else if (val->_to_json_string(val, pb, level + 1, flags) < 0)
	return -1;
	}
	if (flags & JSON_C_TO_STRING_PRETTY)
	{
	if (had_children)
	printbuf_strappend(pb, "\n");
	indent(pb, level, flags);
	}
	if (flags & JSON_C_TO_STRING_SPACED && !(flags & JSON_C_TO_STRING_PRETTY))
	return printbuf_strappend(pb, " ]");
	return printbuf_strappend(pb, "]");
	}

The authors of json-c always pack data into arrays, It cannot be fixed from MTA, as a solution we can just make a parameter which would be cut first and last brackets.

[hawicz]

If I'm reading things right, that toJSON call triggers the toJSON function which calls WriteToJSONString, which calls WriteToJSONArray to explicitly create an array type json_object and then calls json_object_to_json_string_ext on that.

The json-c code is doing exactly what you're asking it to do. This probably needs that extra array wrapping code removed.