Category Archives: Web API 2

Unit Of Work With Multiple DBContexts

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An MVC 5 and Web API 2 application with Automapper, EF 6, repository pattern, dependency injection using Autofac which uses one unit of work to deal with multiple dbcontexts with Async functions.

Features:

  • Entity Framework 6
  • MVC 5 Web App
  • Async MVC 5 Web App
  • MVC 5 WebAPI 2
  • Dependency Injection and IOC using Autofac
  • AutoMapper
  • Unit Of Work with multiple DBContexts
  • Generic Repository with Async functions
  • Service layer with Async functions
  • Code First approach
  • Power of repository extensibility
  • NUnit with Async Tests
  • Moq

This application’s design pattern overcomes most of the redundant code while creating repositories and resolves a unit of work with multiple Dbcontexts.

Dos while creating repositories:

  • Create a generic repository class and generic repository interface which exposes common functions to each entity.
  • Create individual repository classes which extends generic repository with additional functions of its interface where ever it is required.
  • Initialize a generic repository’s local DBContext object through its constructor.
  • Set this DBContext’s entities-set in to the generic repository’s local entities-set object.

Don’ts while creating repositories for unit of work:

  • Do not create multiple repository interface and repository classes for all the repositories which is not required.
  • Do not associate or inject your DBContext object to your generic repository class. Get the DBContext reference from Unit of work class.

Good way of designing your service layer:

  • Create one service class for one controller.
  • Have an individual interface for each service class – Which helps customizing functions related to its service.
  • Inherit generic repository interface to the service interface – Which forces the service class to expand all the methods in generic interface (optional).
  • Inject unit of work objects corresponding to its DBContext in the service constructor.
  • Access repositories through Unit of Work object.
  • Commit all the transactions corresponding to a DBContext once with its Unit of Work object.
  • In the controller inject only its related service object and call its functions for further operations.

Click here to download the code

Hope this design pattern helps. Please let me know if i had missed anything and any suggession to improve this design is welcome.