Data Mapper is a service class software access layer for data that transfers and retrieves domain object data between databases and stored objects. It is a type of Data access Layer that helps in transferring data in 2 directions between objects in memory and storage. It is one of the most important data source patterns in terms of understanding and usage. It takes care of all the persistence business and manages all your data without anybody knowing that a data mapper exists. It is an architectural pattern that includes functions such as read, update, create and delete data that operate on different objects in a data store. The goal of the pattern is to keep the stored memory data representation and the persistent data store independent of each other. In Datamapper the layers are composed of different layers called mappers or data access objects for performing the effective data transfer. Mappers are of two types generic and dedicated. Generic mappers handle many different domain types whereas dedicated mappers handle one or less.
Data mappers generally serve as a middle layer between domain objects and a database and it allows them to evolve independently without anyone depending on the other. Know more at connectid datamapper.
Data mapper patterns:
Data mapper design patterns come under base design mapper. It is a design template that acts as an intermediary for transferring data between persistent storage and database layers represented in-memory data. The design is loaded and used for logical processing of what problems it solves. The aeronautical view gap is the common problem of any programming language. A mapper is an object of computer language that fills up the communication gap between two independent layers also known as objects. The design patterns provide basic solutions to common problems faced by software designs in terms of classes and objects.
It does not need the involvement of SQL code or any knowledge about the database schema.
How does it work?
It mainly separates two sources from each other, the two sources are domain source and data source. There are many details and steps involved to make this addressed specification happen. Taking a simple case of 2 basic sources like persons which are addressed as class 1 that is person 1 and class 2 defined as person 2. Therefore to load any of the person’s data, the user or client calls the mapper to find a method to deal with this type of class. Then the mapper tries to identify and see whether the data of the person already loaded or not, if the data is not accessed the mapper loads it and this is all done by identity Map Pattern.
DataMapper is designed to be more of an abstract ORM (Object-Rational Amper Library) and not SQL. It’s a great software to transfer data between in-memory objects and databases. It simplifies the complexity of data transfer between two schemes to a great extent. The layers in DataMapper composes of one or more mappers who perform the data transfer and the mapper implementations vary in scope.
This was a short article on what data mapper is and how it works.