oatpp-mongo

NOTE:

• BSON ObjectMapper - ready-to-use.
• Database driver - in development. While you can do basic CRUD operations, it’s still on POC stage. API is not ready and it’s not recommended to use.
  To work with MongoDB - use BSON ObjectMapper + mongocxx driver.

oatpp-mongo is the oatpp native client for MongoDB. It contains DTO to BSON mapper plus database driver.

Find the complete example project using oatpp-mongo here

More about Oat++:

• Oat++ Website
• Oat++ Github Repository

How To Build

oatpp-mongo has no extrernal dependencies (The main oatpp module is still required).
libmongoxcc is used (and linked) in module tests only. Use -DOATPP_BUILD_TESTS=OFF option to build without tests and without dependency on libmongoxcc.

Install oatpp-mongo

• Clone this repository.

• In the root of the repository run:

   mkdir build && cd build
   cmake -DOATPP_BUILD_TESTS=OFF ..
   make install

API

Temporary API (using libmongoxcc)

Since oatpp driver is not ready yet, you can use libmongoxcc together with oatpp BSON.

Why using oatpp BSON? - because it’s based on oatpp object-mapping framework and
it’s extremely easy to use.

Create bsonxx::document From Any oatpp Object

/**
 * This is the utility function that you'll need while working libmongoxcc
 */
bsoncxx::document::value Database::createMongoDocument(const oatpp::Void &polymorph) {
  // if you have huge docs, you may want to increase starting BufferOutputStream size.
  // Or you may want to use oatpp::data::stream::ChunkedBuffer instead - for no-copy growth.
  oatpp::data::stream::BufferOutputStream stream;
  m_objectMapper.write(&stream, polymorph); //< Serialize oatpp object to BSON.
  bsoncxx::document::view view(stream.getData(), stream.getCurrentPosition());
  return bsoncxx::document::value(view);
}

Where m_objectMapper - is oatpp::ObjectMapper.

Insert Document

Let’s say you have such DTO defined:

class User : public oatpp::DTO {
  DTO_INIT(User, DTO)
  DTO_FIELD(String, _id);
  DTO_FIELD(String, username);
  DTO_FIELD(Boolean, active);
  DTO_FIELD(String, role);
};

Then you can insert your DTO in the database like this:

collection.insert_one(createMongoDocument(myDto));

You can also insert an arbitrary document using oatpp::Any

collection.insert_one(createMongoDocument(
  oatpp::Fields<oatpp::Any>({
    {"username", oatpp::String("Mr. Porridge")},
    {"role", oatpp::String("Admin")},
    {"jacket-color", oatpp::List<oatpp::String>({"red", "green", "blue"})}
  })
));

Read Document

Let’s say we have the same DTO - User:

  auto result =
    collection.find_one(createMongoDocument( // <-- Filter
      oatpp::Fields<oatpp::String>({
        {"_id", oatpp::String("<id-to-find>")}
      })
    ));
  if(result) {
    auto view = result->view();
    auto bson = oatpp::String((const char*)view.data(), view.length(), false /* to not copy view data */);
    auto user = m_objectMapper.readFromString<oatpp::Object<User>>(bson);
    // TODO - do somthing with user:)
    // You can then serialize it to JSON using oatpp::parser::json::mapping::ObjectMapper
  }

Examples

• example-mongodb - CRUD with MongoDB and Swagger-UI.