CreateExchange creates a new ExchangeTransaction.

CreateGiftHistory creates a new GiftHistory.

CreateUserItem creates a new UserItem.

Disconnect from MongoDB.

Initialize a connection to MongoDB.

ReadAllExchange reads all exchanges from all users.

ReadAllGiftHistory reads all gift history.

ReadAllUserItem reads all user items.

ReadExchange reads all exchanges from a user.

ReadReceiverGiftHistory reads all gift history to a user.

ReadSenderGiftHistory reads all gift history from a user.

ReadUserItem reads all user items from a user.

UpdateUserItem updates a user item.

Client is the MongoDB client object.

ExchangeColl is the collection object for the Exchange collection.

GiftHistoryColl is the collection object for the GiftHistory collection.

UserItemColl is the collection object for the UserItem collection.

User is a struct that represents an admin user.