A specific space in world json causing a parsing error when calling world.from_json()

[ExecMon]

Describe the bug

Json parser error when calling: flecs::world.from_json() because of a specific space char between key/value.

To Reproduce

Call flecs::world.from_json() on this json ("Pos" assumed to be a predefined component):

{"results":[{"name":"#1102", "id":1102,"components":{"sys.module.Pos": {"pos":{"x":0, "y":972, "z":0}}}}]}

And this is the error I get:

error: 1: expected }, got ]
{"results":[{"name":"#1102", "id":1102,"components":{"sys.module.Pos": {"pos":{"x":0, "y":972, "z":0}}}}]}
                                                                                                        ^

Removing the space between "sys.module.Pos": and following { solves the issue.

Expected behavior

White space in json shouldn't cause a parsing error.

Additional context

I tried to reproduce this with the flecs::entity.from_json() call but I couldn't, so this issue might be specific to flecs::world.from_json().

The json exported by to_json() does not add this space of course, but using a json library to parse and edit some value may reformat the json leading to some unanticipated whitespace when converting json back to string.

[SanderMertens]

Are you able to share the component type + reflection code you've used for this? I cannot reproduce this when I create a type with a pos member that is of a type with x, y, z members.

I do get this error when the type does not match the JSON, in which case I get

error: cursor.c: 305: unknown member 'pos' for type 'T'
error: 1: expected }, got ]
{"results":[{"name":"e", "id":1000,"components":{"T": {"pos":{"x":10, "y":20}}}}]}

That's not a bug though, the input is not valid in this case.

[ExecMon]

Sure! I've tested with this module definition:

struct vec3 { float x, y, z; };
struct Pos { vec3 pos; };

namespace sys {
struct module {
	module(flecs::world& ecs) {
		ecs.component<vec3>()
			.member<float>("x")
			.member<float>("y")
			.member<float>("z");
		ecs.component<Pos>()
			.member<vec3>("pos");
	}
};
}

I noticed if I switch the sys.module.Pos in json to use a "Pos" defined as a simple struct Pos { float x, y, z; }; , the parsing error doesn't occur.

[SanderMertens]

Can you try this on the latest release? This code runs for me without errors in 4.0.4:

#include <flecs.h>

struct vec3 { float x, y, z; };
struct Pos { vec3 pos; };

namespace sys {
struct module {
	module(flecs::world& ecs) {
		ecs.component<vec3>()
			.member<float>("x")
			.member<float>("y")
			.member<float>("z");
		ecs.component<Pos>()
			.member<vec3>("pos");
	}
};
}

int main(const int argc, const char **argv)
{
    flecs::world world;

    world.import<sys::module>();

    world.from_json(
      "{\"results\":[{\"name\":\"#1102\", \"id\":1102,\"components\":{\"sys.module.Pos\": {\"pos\":{\"x\":0, \"y\":972, \"z\":0}}}}]}"
    );

    return 0;
}

[ExecMon]

Just tried that code on current master and it ran without errors for me as well.

So I did some more testing and I arrived at this which should reproduce the issue:

#include <iostream>
#include <flecs.h>

struct vec3 { float x, y, z; };
struct Pos { vec3 pos; };

namespace sys {
struct module {
	module(flecs::world& ecs) {
		ecs.component<vec3>()
			.member<float>("x")
			.member<float>("y")
			.member<float>("z");
		ecs.component<Pos>()
			.member<vec3>("pos");
	}
};
}

int main(const int argc, const char **argv)
{

	{
		flecs::world world;
		world.import<sys::module>();

		std::cout << "Unregistered component without space:\n";
		// Doesn't error
		world.from_json(
		"{\"results\":[{\"name\":\"#1102\",\"id\":1102,\"components\":{\"NotPos\":{\"pos\":{\"x\":0, \"y\":972, \"z\":0}}}}]}"
		);
	}

	{
		flecs::world world;
		world.import<sys::module>();

		std::cout << "Unregistered component with space:\n";
		// Thorws error
		world.from_json(
		"{\"results\":[{\"name\":\"#1102\", \"id\":1102,\"components\":{\"NotPos\": {\"pos\":{\"x\":0, \"y\":972, \"z\":0}}}}]}"
		);
	}

	return 0;
}

I'm not sure yet but if this is specific to parsing unregistered components, then it's probably a minor issue/edge case.