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In this article, let's learn about Unit of Work Design Pattern in .NET.

Note: If you have not done so already, I recommend you read the article on Enterprise Design Pattern - Repository.

Table of Contents

1. Introduction
2. What problem does it solve?
3. Implementing a Unit of Work Pattern
4. Working with EF Core
5. Real World Use Cases
6. Summary

Introduction

The Unit of Work pattern is crucial for managing transactions and coordinating multiple data operations across repositories in enterprise software. It ensures consistency by grouping operations into a single unit, where either all operations succeed or none do.

What problem does it solve?

Imagine you have an order processing system. You need to save an order and its associated order lines. Without the Unit of Work, if saving the order succeeds but saving the order lines fails, you could end up with inconsistent data. The Unit of Work pattern solves this by ensuring that both operations are wrapped in a single transaction. If one fails, everything is rolled back, preserving data integrity.

Implementing Unit of Work Pattern

To implement the Unit of Work pattern, start by creating an IUnitOfWork interface that includes methods for committing and rolling back transactions:

Next, create an abstract UnitOfWork class that implements this interface. It should handle transactions through an injected DbContext. Note we are leaving the lifetime of DbContext to IOC container to manage. This is important as DbContext should be scoped to the lifetime of the request.

You can now create a concrete class for specific units of work, such as handling orders and order lines:

Now all we need to do is to use the repositories to do operations and use SaveChanges in Unit of Work to commit the transaction. If any operation fails, the transaction will be rolled back.

Working with EF Core

Entity Framework Core naturally implements the Unit of Work pattern via the DbContext. When you call SaveChanges, all tracked changes are wrapped in a transaction, ensuring either all changes are committed or none are.

Real World Use Cases

• Banking Applications: In financial transactions, like transferring funds between accounts, the Unit of Work ensures that both deduction and addition occur within a single transaction. If any part fails, the entire operation is rolled back.
• E-commerce Checkout: During the checkout process, actions like updating the cart, reserving inventory, and placing an order are coordinated by the Unit of Work. If inventory reservation fails, the whole transaction is rolled back, preventing incomplete orders.

Summary

The Unit of Work pattern is essential for managing transactions in data-intensive applications. It ensures data integrity by coordinating multiple operations in a single transaction. With Entity Framework Core, much of this functionality is already built-in, allowing you to leverage this pattern with minimal setup.