ObjectID

Table of Contents

• Basic Usage
• Error Handling

How to use ObjectID (OID) interfaces.

Basic Usage

void example() {
    {
        bsoncxx::oid a;
        bsoncxx::oid b;
 
        ASSERT(a != b);  // Random and unique per process.
    }
 
    {
        char bytes[bsoncxx::oid::k_oid_length]{};
 
        bsoncxx::oid oid{bytes, sizeof(bytes)};
 
        {
            std::time_t time = oid.get_time_t();
            char str[sizeof("YYYY-MM-DD HH:MM:SS")];
            ASSERT(std::strftime(str, sizeof(str), "%F %T", std::gmtime(&time)) ==
                   sizeof(str) - 1u);
            ASSERT(std::string(str) == "1970-01-01 00:00:00");
        }
 
        ASSERT(oid.bytes() != bytes);  // Seperate storage.
        ASSERT(oid.size() == bsoncxx::oid::k_oid_length);
        ASSERT(std::memcmp(bytes, oid.bytes(), oid.size()) == 0);
 
        ASSERT(oid.to_string() == "000000000000000000000000");
        ASSERT(oid == bsoncxx::oid{"000000000000000000000000"});
    }
 
    {
        // Timestamp: 946771199 (0x386e94ff)
        // Value:     286462997 (0x11131415)
        // Counter:   2171427   (0x212223)
        bsoncxx::oid oid{"386e94ff1112131415212223"};
 
        {
            std::time_t time = oid.get_time_t();
            char str[sizeof("YYYY-MM-DD HH:MM:SS")];
            ASSERT(std::strftime(str, sizeof(str), "%F %T", std::gmtime(&time)) ==
                   sizeof(str) - 1u);
            ASSERT(std::string(str) == "2000-01-01 23:59:59");
        }
 
        ASSERT(oid < bsoncxx::oid{"389622001112131415212223"});  // Timestamp: 2000-02-01 00:00:00
        ASSERT(oid > bsoncxx::oid{"386d43801112131415212223"});  // Timestamp: 2000-01-01 00:00:00
        ASSERT(oid < bsoncxx::oid{"386e94ffffffffffff212223"});  // Value: 1099511627775
        ASSERT(oid > bsoncxx::oid{"386e94ff0000000000212223"});  // Value: 0
        ASSERT(oid < bsoncxx::oid{"386e94ff1112131415ffffff"});  // Counter: 16777215
        ASSERT(oid > bsoncxx::oid{"386e94ff1112131415000000"});  // Counter: 0
    }
}

Error Handling

void example() {
    try {
        bsoncxx::oid oid{"invalid"};  // Throws.
 
        ASSERT(false && "should not reach this point");
    } catch (const bsoncxx::exception& ex) {
        ASSERT(ex.code() == bsoncxx::error_code::k_invalid_oid);
    }
 
    try {
        char bytes[1]{};
 
        bsoncxx::oid oid{bytes, sizeof(bytes)};  // Throws.
 
        ASSERT(false && "should not reach this point");
    } catch (const bsoncxx::exception& ex) {
        ASSERT(ex.code() == bsoncxx::error_code::k_invalid_oid);
    }
}