Treat JSON as resource files.

This makes the files ended in ".json" be treated as Godot resources.
This solves two problems:
* Avoid extensions to implement their own handling, which results in conflicts (all must use this one).
* Allow code to still work opening it as a file (since it will not be imported).

core/io/json.cpp

@@ -497,6 +497,10 @@ Error JSON::_parse_object(Dictionary &object, const char32_t *p_str, int &index,
 	return ERR_PARSE_ERROR;
 }
 
+void JSON::set_data(const Variant &p_data) {
+	data = p_data;
+}
+
 Error JSON::_parse_string(const String &p_json, Variant &r_ret, String &r_err_str, int &r_err_line) {
 	const char32_t *str = p_json.ptr();
 	int idx = 0;
@@ -557,6 +561,88 @@ void JSON::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("parse", "json_string"), &JSON::parse);
 
 	ClassDB::bind_method(D_METHOD("get_data"), &JSON::get_data);
+	ClassDB::bind_method(D_METHOD("set_data", "data"), &JSON::set_data);
 	ClassDB::bind_method(D_METHOD("get_error_line"), &JSON::get_error_line);
 	ClassDB::bind_method(D_METHOD("get_error_message"), &JSON::get_error_message);
+
+	ADD_PROPERTY(PropertyInfo(Variant::NIL, "data", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT), "set_data", "get_data"); // Ensures that it can be serialized as binary.
+}
+
+////
+
+////////////
+
+Ref<Resource> ResourceFormatLoaderJSON::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
+	if (r_error) {
+		*r_error = ERR_FILE_CANT_OPEN;
+	}
+
+	if (!FileAccess::exists(p_path)) {
+		*r_error = ERR_FILE_NOT_FOUND;
+		return Ref<Resource>();
+	}
+
+	Ref<JSON> json;
+	json.instantiate();
+
+	Error err = json->parse(FileAccess::get_file_as_string(p_path));
+	if (err != OK) {
+		if (r_error) {
+			*r_error = err;
+		}
+		ERR_PRINT("Error parsing JSON file at '" + p_path + "', on line " + itos(json->get_error_line()) + ": " + json->get_error_message());
+		return Ref<Resource>();
+	}
+
+	if (r_error) {
+		*r_error = OK;
+	}
+
+	return json;
+}
+
+void ResourceFormatLoaderJSON::get_recognized_extensions(List<String> *p_extensions) const {
+	p_extensions->push_back("json");
+}
+
+bool ResourceFormatLoaderJSON::handles_type(const String &p_type) const {
+	return (p_type == "JSON");
+}
+
+String ResourceFormatLoaderJSON::get_resource_type(const String &p_path) const {
+	String el = p_path.get_extension().to_lower();
+	if (el == "json") {
+		return "JSON";
+	}
+	return "";
+}
+
+Error ResourceFormatSaverJSON::save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags) {
+	Ref<JSON> json = p_resource;
+	ERR_FAIL_COND_V(json.is_null(), ERR_INVALID_PARAMETER);
+
+	String source = JSON::stringify(json->get_data(), "\t", false, true);
+
+	Error err;
+	Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::WRITE, &err);
+
+	ERR_FAIL_COND_V_MSG(err, err, "Cannot save json '" + p_path + "'.");
+
+	file->store_string(source);
+	if (file->get_error() != OK && file->get_error() != ERR_FILE_EOF) {
+		return ERR_CANT_CREATE;
+	}
+
+	return OK;
+}
+
+void ResourceFormatSaverJSON::get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const {
+	Ref<JSON> json = p_resource;
+	if (json.is_valid()) {
+		p_extensions->push_back("json");
+	}
+}
+
+bool ResourceFormatSaverJSON::recognize(const Ref<Resource> &p_resource) const {
+	return p_resource->get_class_name() == "JSON"; //only json, not inherited
 }

core/io/json.h

@@ -31,7 +31,9 @@
 #ifndef JSON_H
 #define JSON_H
 
-#include "core/object/ref_counted.h"
+#include "core/io/resource.h"
+#include "core/io/resource_loader.h"
+#include "core/io/resource_saver.h"
 #include "core/variant/variant.h"
 
 class JSON : public RefCounted {
@@ -86,8 +88,24 @@ public:
 	static Variant parse_string(const String &p_json_string);
 
 	inline Variant get_data() const { return data; }
+	void set_data(const Variant &p_data);
 	inline int get_error_line() const { return err_line; }
 	inline String get_error_message() const { return err_str; }
 };
 
+class ResourceFormatLoaderJSON : public ResourceFormatLoader {
+public:
+	virtual Ref<Resource> load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
+	virtual void get_recognized_extensions(List<String> *p_extensions) const;
+	virtual bool handles_type(const String &p_type) const;
+	virtual String get_resource_type(const String &p_path) const;
+};
+
+class ResourceFormatSaverJSON : public ResourceFormatSaver {
+public:
+	virtual Error save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags = 0);
+	virtual void get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const;
+	virtual bool recognize(const Ref<Resource> &p_resource) const;
+};
+
 #endif // JSON_H

core/register_core_types.cpp

@@ -87,6 +87,8 @@ static Ref<TranslationLoaderPO> resource_format_po;
 static Ref<ResourceFormatSaverCrypto> resource_format_saver_crypto;
 static Ref<ResourceFormatLoaderCrypto> resource_format_loader_crypto;
 static Ref<NativeExtensionResourceLoader> resource_loader_native_extension;
+static Ref<ResourceFormatSaverJSON> resource_saver_json;
+static Ref<ResourceFormatLoaderJSON> resource_loader_json;
 
 static core_bind::ResourceLoader *_resource_loader = nullptr;
 static core_bind::ResourceSaver *_resource_saver = nullptr;
@@ -211,6 +213,12 @@ void register_core_types() {
 	resource_format_loader_crypto.instantiate();
 	ResourceLoader::add_resource_format_loader(resource_format_loader_crypto);
 
+	resource_loader_json.instantiate();
+	ResourceLoader::add_resource_format_loader(resource_loader_json);
+
+	resource_saver_json.instantiate();
+	ResourceSaver::add_resource_format_saver(resource_saver_json);
+
 	GDREGISTER_CLASS(MainLoop);
 	GDREGISTER_CLASS(Translation);
 	GDREGISTER_CLASS(OptimizedTranslation);
@@ -387,6 +395,12 @@ void unregister_core_types() {
 	ResourceLoader::remove_resource_format_loader(resource_format_loader_crypto);
 	resource_format_loader_crypto.unref();
 
+	ResourceSaver::remove_resource_format_saver(resource_saver_json);
+	resource_saver_json.unref();
+
+	ResourceLoader::remove_resource_format_loader(resource_loader_json);
+	resource_loader_json.unref();
+
 	if (ip) {
 		memdelete(ip);
 	}

doc/classes/JSON.xml

@@ -6,7 +6,7 @@
 	<description>
 		The [JSON] enables all data types to be converted to and from a JSON string. This useful for serializing data to save to a file or send over the network.
 		[method stringify] is used to convert any data type into a JSON string.
-		[method parse] is used to convert any existing JSON data into a [Variant] that can be used within Godot. If successfully parsed, use [method get_data] to retrieve the [Variant], and use [code]typeof[/code] to check if the Variant's type is what you expect. JSON Objects are converted into a [Dictionary], but JSON data can be used to store [Array]s, numbers, [String]s and even just a boolean.
+		[method parse] is used to convert any existing JSON data into a [Variant] that can be used within Godot. If successfully parsed, use [member data] to retrieve the [Variant], and use [code]typeof[/code] to check if the Variant's type is what you expect. JSON Objects are converted into a [Dictionary], but JSON data can be used to store [Array]s, numbers, [String]s and even just a boolean.
 		[b]Example[/b]
 		[codeblock]
 		var data_to_send = ["a", "b", "c"]
@@ -16,7 +16,7 @@
 		# Retrieve data
 		var error = json.parse(json_string)
 		if error == OK:
-		    var data_received = json.get_data()
+		    var data_received = json.data
 		    if typeof(data_received) == TYPE_ARRAY:
 		        print(data_received) # Prints array
 		    else:
@@ -32,13 +32,6 @@
 	<tutorials>
 	</tutorials>
 	<methods>
-		<method name="get_data" qualifiers="const">
-			<return type="Variant" />
-			<description>
-				Returns the [Variant] containing the data of a successful [method parse].
-				[b]Note:[/b] It will return [code]Null[/code] if the last call to parse was unsuccessful or [method parse] has not yet been called.
-			</description>
-		</method>
 		<method name="get_error_line" qualifiers="const">
 			<return type="int" />
 			<description>
@@ -56,7 +49,7 @@
 			<param index="0" name="json_string" type="String" />
 			<description>
 				Attempts to parse the [param json_string] provided.
-				Returns an [enum Error]. If the parse was successful, it returns [code]OK[/code] and the result can be retrieved using [method get_data]. If unsuccessful, use [method get_error_line] and [method get_error_message] for identifying the source of the failure.
+				Returns an [enum Error]. If the parse was successful, it returns [code]OK[/code] and the result can be retrieved using [member data]. If unsuccessful, use [method get_error_line] and [method get_error_message] for identifying the source of the failure.
 				Non-static variant of [method parse_string], if you want custom error handling.
 			</description>
 		</method>
@@ -118,4 +111,9 @@
 			</description>
 		</method>
 	</methods>
+	<members>
+		<member name="data" type="Variant" setter="set_data" getter="get_data" default="null">
+			Contains the parsed JSON data in [Variant] form.
+		</member>
+	</members>
 </class>