Operation Exceptions

Table of Contents

• As a Regular Exception
• As an Operation Exception

How to handle exceptions thrown by database and collection operations.

As a Regular Exception

Warning

The mongocxx::server_error_category error category is overloaded (CXX-834). The error code value may belong to the server, mongoc, or libmongocrypt depending on the context. Use error code values with caution.

void example(mongocxx::database db) {
    EXPECT(db.name() == "db");
 
    // The `getParameter` command can only be run in the `admin` database.
    auto cmd = bsoncxx::from_json(R"({"getParameter": "*"})");
 
    // This error handling pattern applies to all commands which may throw a
    // `mongocxx::operation_exception` exception.
    try {
        auto reply = db.run_command(cmd.view());
 
        EXPECT(false && "should not reach this point");
    } catch (mongocxx::exception const& ex) {
        EXPECT(ex.code().category() == mongocxx::server_error_category());
        EXPECT(ex.code().value() == 13); // Unauthorized
        EXPECT(std::strstr(ex.what(), "admin") != nullptr);
    }
}

As an Operation Exception

Note

Using mongocxx::exception for error handling is recommended for forward compatibility. (CXX-2377)

void example(mongocxx::database db) {
    EXPECT(db.name() == "db");
 
    // The `getParameter` command can only be run in the `admin` database.
    auto cmd = bsoncxx::from_json(R"({"getParameter": "*"})");
 
    // This error handling pattern applies to all commands which may throw a
    // `mongocxx::operation_exception` exception.
    try {
        auto reply = db.run_command(cmd.view());
 
        EXPECT(false && "should not reach this point");
    } catch (mongocxx::operation_exception const& ex) {
        EXPECT(ex.code().category() == mongocxx::server_error_category());
        EXPECT(ex.code().value() == 13); // Unauthorized
        EXPECT(std::strstr(ex.what(), "admin") != nullptr);
 
        if (auto server_error_opt = ex.raw_server_error()) {
            bsoncxx::document::view server_error = server_error_opt->view();
 
            EXPECT(server_error["ok"]);
            EXPECT(server_error["ok"].get_double().value == 0.0);
 
            EXPECT(server_error["code"]);
            EXPECT(server_error["code"].get_int32().value == ex.code().value());
 
            EXPECT(server_error["codeName"]);
            EXPECT(server_error["errmsg"]);
            // ... other error fields.
        }
    }
}