Glad you found the article and the EfCore.GenericServices library useful. description of what I do in real applications. Also, we must add project references of Generic Repository Entity Framework and Shared Kernel project libraries. This article is the typical way I learn I try something and then I look back to see if I could have done it better. It will be necessary that you know the basics of object oriented programming, domain driven design (DDD) approach, Microsoft ORM Entity Framework, unit testing, and solid principles of object oriented design, introduced by Robert C. Martin. Aggregate root i responsible for transaction. (KISS principle). I am a freelance .NET Core back-end developer. It's a great and clean code and also really helpful article. After getting the success message for update-database command, go and check the database, a database called EShoppingTutorialDB with two tables must be created as we configured before in entity mapping configurations as shown in the image below: Alright, we have successfully created database and tables, so lets go and complete the other parts of the application like: unit of work, order repository and web API controllers. This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL), General News Suggestion Question Bug Answer Joke Praise Rant Admin. In the diagram below I have a trivial requirement to update the publication date of a book. But keep in mind also, that one size does not fit all. But the main point is that it doesnt need to load the existing reviews to add a new review it just adds a single review. It was a good article, I hope it will be useful for all programmers and they will implement their programs with the same logic. DDD approach, as shown in my article Architecture This is fairly long article which covers both CRUD (Create, Read, Update and Delete) functions and business logic function. the business logic you can create your own business-only classes. but all in one class. the code is in one place and DRY (only one version of this business logic I would say I am back up to the Notice that no repository implementation will be added to the application core domain. Nowadays we build really complex applications really quickly see EF Core docs where it defines Sorry I missed your comment. Still my question is if we provide method name in the second parameter of UpdateAndSaveAsync(), will Generic Service still try to match the other methods? Business logic that uses multiple entity classes, e.g. library by using AutoMappers object-to-object mapping. have the collection of Reviews loaded, so how do we handle this? The repository pattern offers an interface and provides methods to add, remove, and retrieve domain entities, to enable the domain entities to remain agnostic of the underlying data persistence layer (Persistence Ignorance), encouraging loosely coupling programming and allowing to extend application layers independently, which leads us to test the business logic in isolation from external dependencies (testable and agile architecture principle). Ill have a look at it, but most likely not till the weekend. m agree with you, but in this imaginary sample tutorial, I just wanted to show the whole structure of domain driven implementation, and in real world scenarios the implementation method of MoneySymbols will not be suggested. Unit of Work Design Pattern coordinates the data persistence operations of multiple business objects changes as one atomic transaction, which guarantees the entire transaction will be committed or rolled back. Repeat this scenario for NuGet packages Microsoft.EntityFrameworkCore.SqlServer and Microsoft.EntityFrameworkCore.Tools. DTO doesnt pass some validation checks, etc. This Library will contain only three .CS files, repository interface, repository implementation and SortingExtension static helper class in order to sort fetched records from database in ascending or descending order. EF Core navigational properties (basically the links to other tables), and how How do you solve that? Some of the other articles I have written about Domain-Driven However I still find the terms CRUD or Business logic useful to categorise the functions I need to code. I want to use the code to extend my apis. The GenericServices can now live outside your domain layer. I have found my EfCore.GenericBizRunner library

According to this, Id place to Book and Review classes within Layer 1 (Domain). Also you mention that review has to be a member of a book. The only extra line not shown Hi Jon, To make it concrete: assuming I want to add a new Review to a Book via AddReview() (see here). Your business logic works on a series of in-memory relationship in DDD is Root service or as business logic. Once I had that I was full on with DDD, but I found that came at a cost

Here are the bigger client projects where I used an DDD approach: This article looks at what I have learnt along the way. It depends on so may things.

We will look at the software design principles, frameworks and tools that we can use in the implementation effort. The term Domain-Driven Design (DDD) was coined by Eric Evans in his book in 2004. But regardless of all the efforts that we put in in this article, my motto is that: "one size does not fit all". Article seems well made and properly explained, at a first glance. Alright, so far so good. That works OK, but you dont get the level of separation that type 4 gives you. nut, or in software principle, KISS (Keep it Simple, Stupid). For this business type, then its correct to apply a strong For that I use my EfCore.GenericServices to do that (if I hadnt got that I would have to inject a DbContext into the entity classes). This example is taken from the https://github.com/JonPSmith/EfCore.GenericServices repo. the best library I have built so far.

The last sentence It shouldnt throw an exception so something funny is going on. of Business Layer working with Entity Framework (Core and v6) revisited. business logic type 4. All right, the next step to generating database and tables via code first approach will be adding database connection strings, for this, at first we want to add an ASP.NET Core web API project to the solution in EShoppingTutorial folder, and then we add the connection string in a web API project as shown in the image below: In the next form, select API template, and remove tick for Configure for Https as shown in the image below: For the next step, we add Nuget packages for Microsoft Entity Framework Core, and Microsoft EntityFrameworkCore Design, and project references for EShoppingTutorial.Core and SharedKernel as we did before in this article. Thank you so much for sharing this. Right click on application solution name and click Manage NuGet Packages for Solution. public class RemoveReviewDto : ILinkToEntity{ the term navigation properties. I find that makes the writing the code much easier, as youre not Microsoft Entity Framework Code-First will also create the database tables and fields with the name of DbSet properties in the DbContext class by convention, so why did we separate mapping files and do extra work? Could you raise an issue in https://github.com/JonPSmith/EfCore.GenericServices with your Book class and your DTO.

as domain entities in DDD, and I use the term entity classes in Also, we will have access to EShoppingTutorial DbContext. EF6.x library called GenericServices. I have used a DDD approach for many years, but it wasnt until For instance, I do this for an Order of a Book, because these two entities are not in the same root/aggregate. If there are a several different business Do you sometime use GenericServices along side BizLogic in a single project? Also, some of it repetitious (and boring! rather than the technology. and the whole application should probably work fine with minimum or no changes in inner layers (core domain). NOTE: Im not explaining why I use a backing field, _reviews, in this example. be done via a method in the Book entity class (the term for the Book/Reviews See my Entity Framework Core in Action book. }, But Im getting this error, not sure what Im doing wrong, System.NullReferenceException: Object reference not set to an instance of an object. Also, for a brief overview of the solid principles, you can just type few words in Google like: "solid principles of object oriented design". I find that business logic ranges from something I also have a NuGet Status logic used a repository pattern to handle the database accesses. Article Copyright 2021 by Amanmohammad Toumaj, Throws Exception if Maximum price has been reached, or if no Order Item has been added to this Order, Throws Exception if Maximum price has been reached, Scans a given assembly for all types that implement, IEntityTypeConfiguration, and registers each one automatically, Data Source=localhost\\SQLEXPRESS; As you see, this implementation of the Unit of Work pattern is not a too complex, it only contains the repositories, and a simple ComleteAsync method in order to save all application repository changes, and it also acts as a creational pattern and a placeholder, which will decrease the number of repository injections in the domain or application services, and will lead the application to stay simple and easy to maintain. Repository pattern gives us clean, testable and maintainable approach to access and manipulate data in our applications. approaches depending on the type and complex of the business logic. approaches to Domain-Driven Design with Entity Framework Core, GenericServices to write good, testable ASP.NET Core Web API code quickly, Pragmatic That works, but some people dont like having the DbContext accessible Core/EF Core application to take it to its first release. action has changed, but its the same length.

To shorten our work, I used the ApplyConfigurationsFromAssembly command to apply entity mappings.

This section gives a more nuanced So, without connecting to any external service or database repository, we can easily write unit tests in order to check models behavior (business rules). Im using DDD so I place business logic inside the entity classes as long as the business logic worked on the root or aggregate entities for instance, adding a Review to a book. because the millions of libraries and documentation that is so easy to access. So, having separated entity mapping files gives us lots of opportunities, and it also leads us to clean architecture principles for better refactoring and debugging in the future. IHope you dont mind, but I tweeted your comment see https://twitter.com/thereformedprog/status/1269203325452517376 Its nice to know it a) was used for such a good use, and b) that it speeded up your development! That isnt what I, or my clients, want. If thats what you are asking then the answer is yes. So if you want to know more about this development approach, please type a few words in Google just like: "Domain Driven Design Implementation Approach". My experience is that the first two can be done by via my GenericServices library.

in the same code, because its quick. add a Review to a Book (think Amazon reviews). If youre adding a review without checking others belonging to a book, then maybe review should be your aggregate root instead? where time is money. is useful but a bit heavy, so I tend to only it if the business logic is different DDD approach to the one I usually use, which taught me a lot. We followed up lots of topics like: domain driven, test driven, loosely coupled programming, to have a clean, easy to understand, and maintainable application, that will demonstrate the application's behavior and business logic in its domain models in an object oriented manner (self intention reveals application). features linked to one entity/area I would typically put a method for each function, at System.Linq.Enumerable.SelectIListIterator`2.MoveNext() The IncludeThen is added to the DTO which has properties that match the methods parameters (see this example in one of my articles) . it with the dependency injection service. Practically, I put the business logic in a class and register So before going further, we must add the NuGet packages for entity framework core, like image below. Design: For instance, one my clients project used a clean architecture approach with DDD. of a method to add a new Review to a Book. We will look at domain elements (building blocks) such asEntities, Value Objects, Aggregate Root Entity, Data Transfer Object (DTO), Services, and Repositories.

Sorry, you code will work. at System.String.Join(String separator, IEnumerable`1 values) All right, adding nuget packages to the project is done. Open package manager console and in the default project menu, make sure that you have selected EShoppingTutorial.Core, and then run add-migration command.

This article is about my experiences of applying a Domain-Driven Design (DDD) approach when working with Entity Framework Core (EF Core). It applies encapsulation and information hiding, as you see below, there is one-way relation to Order Items entity, and the only way to access the OrderItems data in application will be via this aggregate root rich entity model. exists), so if the code starts to get complex, then I can always take it up to As I talked about it in the DDD section at the beginning of this article, application domain will remain pure and persistence agnostic, and we will only add the repository interfaces in application domain folder, as shown in the image below, the repository implementations are separated from the application core domain. Not quite sure what you are asking. I dont have an example of type 3 business logic in my own code, but I was called in towards the end of the project to help out and it wasnt appropriate to add my EfCore.GenericBizRunner and the BizLogic and BizDbAccess layers so I just build classes in the ServiceLayer to hold the business logic. Do you have some comments or examples you can share about business logic type 3 working over multiple entity classes?