Merge pull request #9 from oberbichler/feature/from-json

Add `from_json`

README.md

@@ -1,6 +1,6 @@
 # Protosaurus
 
-Parse ProtoBuffer messages at runtime.
+Parse and create ProtoBuffer messages at runtime.
 
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@@ -58,5 +58,12 @@ data = ctx.to_json('Animal', b64decode('CglJZ3Vhbm9kb24QARkAAAAAAAAkQA=='))
 data = ctx.to_json('Animal', bytes.fromhex('0a09496775616e6f646f6e1001190000000000002440'))
 
 print(data)
-# >>> {"name":"Iguanodon","diet":"herbivorous","length":10}
+# >>> '{"name":"Iguanodon","diet":"herbivorous","length":10}'
+
+
+# convert json to protobuf
+data = ctx.from_json('Animal', json.dumps({"name":"Iguanodon","diet":"herbivorous","length":10}))
+
+print(data)
+# >>> b'\n\tIguanodon\x10\x01\x19\x00\x00\x00\x00\x00\x00$@'
 ```

include/protosaurus/protosaurus.h

@@ -1,7 +1,5 @@
 #pragma once
 
-#include "detail/json.h"
-
 #include <protosaurus/protosaurus.h>
 
 #include <nanobind/nanobind.h>
@@ -13,6 +11,7 @@
 #include <google/protobuf/io/tokenizer.h>             // Tokenizer
 #include <google/protobuf/io/zero_copy_stream_impl.h> // ArrayInputStream
 #include <google/protobuf/message.h>                  // Message
+#include <google/protobuf/util/json_util.h>           // MessageToJsonString, 
 
 #include <ios>                                        // boolalpha
 #include <iosfwd>                                     // ostream
@@ -92,13 +91,49 @@ class Context {
 
     // write json
 
-    std::stringstream out;
+    std::string out;
+
+    absl::Status status = util::MessageToJsonString(*message, &out);
+
+    return out;
+  }
+
+  nb::bytes from_json(std::string message_type, std::string data) {
+    // get descriptor
+
+    const Descriptor* descriptor = m_pool.FindMessageTypeByName(message_type);
+
+    if (descriptor == nullptr) {
+      throw std::runtime_error("Could not find descriptor for message type \"" + message_type + "\"");
+    }
+
+    // generate prototype message
+
+    DynamicMessageFactory factory;
+
+    const Message* prototype = factory.GetPrototype(descriptor);
+
+    if (prototype == nullptr) {
+      throw std::runtime_error("Could not create prototype");
+    }
+
+    // parse data
+
+    std::unique_ptr<Message> message(prototype->New());
+
+    if (message == nullptr) {
+      throw std::runtime_error("Could not create empty message from prototype");
+    }
+
+    // write json
+
+    std::string out;
 
-    out << std::boolalpha;
+    absl::Status status = util::JsonStringToMessage(data, message.get());
 
-    detail::push_msg(out, *message);
+    message->SerializeToString(&out);
 
-    return out.str();
+    return nb::bytes(out.c_str(), out.size());
   }
 };
 

src/protosaurus_ext.cpp

@@ -9,5 +9,6 @@ NB_MODULE(protosaurus_ext, m) {
   nb::class_<Context>(m, "Context")
     .def(nb::init<>())
     .def("add_proto", &Context::add_proto, "name"_a, "content"_a)
-    .def("to_json", &Context::to_json, "message_type"_a, "data"_a);
+    .def("to_json", &Context::to_json, "message_type"_a, "data"_a)
+    .def("from_json", &Context::from_json, "message_type"_a, "json"_a);
 }