Big data have received a great deal of attention in recent years. Not only is the amount of data on a completely different level than before, but also the authors have different type of data including factors such as format, structure, and sources. This has definitely changed the tools one needs to handle big data, giving rise to NoSQL systems. While NoSQL systems have proven their efficiency to handle big data, it's still an unsolved problem how the automatic storage of big data in NoSQL systems could be done. This paper proposes an automatic approach for implementing UML conceptual models in NoSQL systems, including the mapping of the associated OCL constraints to the code required for checking them. In order to demonstrate the practical applicability of the work, this paper has realized it in a tool supporting four fundamental OCL expressions: iterate-based expressions, OCL predefined operations, If expression, and Let expression.