diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index abfb8f94b..135e2cfcd 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -1530,7 +1530,16 @@ minetest.parse_json(string[, nullvalue]) -> something
^ nullvalue: returned in place of the JSON null; defaults to nil
^ On success returns a table, a string, a number, a boolean or nullvalue
^ On failure outputs an error message and returns nil
-^ Example: parse_json("[10, {\"a\":false}]") -> {[1] = 10, [2] = {a = false}}
+^ Example: parse_json("[10, {\"a\":false}]") -> {10, {a = false}}
+minetest.write_json(data[, styled]) -> string
+^ Convert a Lua table into a JSON string
+^ styled: Outputs in a human-readable format if this is set, defaults to false
+^ Un-serializable things like functions and userdata are saved as null.
+^ Warning: JSON is more strict than the Lua table format.
+ 1. You can only use strings and positive integers of at least one as keys.
+ 2. You can not mix string and integer keys.
+ This is due to the fact that Javascript has two distinct array and object values.
+^ Example: write_json({10, {a = false}}) -> "[10, {\"a\": false}]"
minetest.serialize(table) -> string
^ Convert a table containing tables, strings, numbers, booleans and nils
into string form readable by minetest.deserialize
diff --git a/src/script/common/c_content.cpp b/src/script/common/c_content.cpp
index cf9f28d30..8eb57ba41 100644
--- a/src/script/common/c_content.cpp
+++ b/src/script/common/c_content.cpp
@@ -1081,3 +1081,52 @@ bool push_json_value(lua_State *L, const Json::Value &value, int nullindex)
else
return false;
}
+
+// Converts Lua table --> JSON
+void get_json_value(lua_State *L, Json::Value &root, int index)
+{
+ int type = lua_type(L, index);
+ if (type == LUA_TBOOLEAN) {
+ root = (bool) lua_toboolean(L, index);
+ } else if (type == LUA_TNUMBER) {
+ root = lua_tonumber(L, index);
+ } else if (type == LUA_TSTRING) {
+ size_t len;
+ const char *str = lua_tolstring(L, index, &len);
+ root = std::string(str, len);
+ } else if (type == LUA_TTABLE) {
+ lua_pushnil(L);
+ while (lua_next(L, index)) {
+ // Key is at -2 and value is at -1
+ Json::Value value;
+ get_json_value(L, value, lua_gettop(L));
+
+ Json::ValueType roottype = root.type();
+ int keytype = lua_type(L, -1);
+ if (keytype == LUA_TNUMBER) {
+ lua_Number key = lua_tonumber(L, -1);
+ if (roottype != Json::nullValue && roottype != Json::arrayValue) {
+ throw LuaError(NULL, "Can't mix array and object values in JSON");
+ } else if (key < 1) {
+ throw LuaError(NULL, "Can't use zero-based or negative indexes in JSON");
+ } else if (floor(key) != key) {
+ throw LuaError(NULL, "Can't use indexes with a fractional part in JSON");
+ }
+ root[(Json::ArrayIndex) key - 1] = value;
+ } else if (keytype == LUA_TSTRING) {
+ if (roottype != Json::nullValue && roottype != Json::objectValue) {
+ throw LuaError(NULL, "Can't mix array and object values in JSON");
+ }
+ root[lua_tostring(L, -1)] = value;
+ } else {
+ throw LuaError(NULL, "Lua key to convert to JSON is not a string or number");
+ }
+ }
+ } else if (type == LUA_TNIL) {
+ root = Json::nullValue;
+ } else {
+ throw LuaError(NULL, "Can only store booleans, numbers, strings, objects, arrays, and null in JSON");
+ }
+ lua_pop(L, 1); // Pop value
+}
+
diff --git a/src/script/common/c_content.h b/src/script/common/c_content.h
index 27019e29e..3b85e5403 100644
--- a/src/script/common/c_content.h
+++ b/src/script/common/c_content.h
@@ -150,6 +150,9 @@ void luaentity_get (lua_State *L,u16 id);
bool push_json_value (lua_State *L,
const Json::Value &value,
int nullindex);
+void get_json_value (lua_State *L,
+ Json::Value &root,
+ int index);
extern struct EnumString es_TileAnimationType[];
diff --git a/src/script/lua_api/l_util.cpp b/src/script/lua_api/l_util.cpp
index fe10e4f57..9fa6fcb77 100644
--- a/src/script/lua_api/l_util.cpp
+++ b/src/script/lua_api/l_util.cpp
@@ -179,6 +179,32 @@ int ModApiUtil::l_parse_json(lua_State *L)
return 1;
}
+// write_json(data[, styled]) -> string
+int ModApiUtil::l_write_json(lua_State *L)
+{
+ NO_MAP_LOCK_REQUIRED;
+
+ bool styled = false;
+ if (!lua_isnone(L, 2)) {
+ styled = lua_toboolean(L, 2);
+ lua_pop(L, 1);
+ }
+
+ Json::Value root;
+ get_json_value(L, root, 1);
+
+ std::string out;
+ if (styled) {
+ Json::StyledWriter writer;
+ out = writer.write(root);
+ } else {
+ Json::FastWriter writer;
+ out = writer.write(root);
+ }
+ lua_pushlstring(L, out.c_str(), out.size());
+ return 1;
+}
+
// get_dig_params(groups, tool_capabilities[, time_from_last_punch])
int ModApiUtil::l_get_dig_params(lua_State *L)
{
@@ -249,6 +275,7 @@ void ModApiUtil::Initialize(lua_State *L, int top)
API_FCT(setting_save);
API_FCT(parse_json);
+ API_FCT(write_json);
API_FCT(get_dig_params);
API_FCT(get_hit_params);
diff --git a/src/script/lua_api/l_util.h b/src/script/lua_api/l_util.h
index d91c880cf..13357587a 100644
--- a/src/script/lua_api/l_util.h
+++ b/src/script/lua_api/l_util.h
@@ -64,6 +64,9 @@ private:
// parse_json(str[, nullvalue])
static int l_parse_json(lua_State *L);
+ // write_json(data[, styled])
+ static int l_write_json(lua_State *L);
+
// get_dig_params(groups, tool_capabilities[, time_from_last_punch])
static int l_get_dig_params(lua_State *L);