https://github.com/ardalis/specification
Base class with tests for adding specifications to a DDD model
https://github.com/ardalis/specification
ddd design-patterns domain-driven-design dotnet hacktoberfest repository-pattern specification-pattern
Last synced: 11 days ago
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Base class with tests for adding specifications to a DDD model
- Host: GitHub
- URL: https://github.com/ardalis/specification
- Owner: ardalis
- License: mit
- Created: 2018-02-13T16:42:06.000Z (about 7 years ago)
- Default Branch: main
- Last Pushed: 2025-03-19T21:42:57.000Z (about 1 month ago)
- Last Synced: 2025-04-03T13:03:09.419Z (18 days ago)
- Topics: ddd, design-patterns, domain-driven-design, dotnet, hacktoberfest, repository-pattern, specification-pattern
- Language: C#
- Homepage:
- Size: 775 KB
- Stars: 2,039
- Watchers: 26
- Forks: 252
- Open Issues: 13
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
README
[](https://www.nuget.org/packages/Ardalis.Specification)
[](https://github.com/ardalis/Specification/actions/workflows/ci.yml)
[](https://ardalis.github.io/Specification/)
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## Give a Star! :star:
If you like or are using this project please give it a star. Thanks!
# Specification
Base class with tests for adding specifications to a DDD model. Also includes a default generic Repository base class with support for EF6 and EF Core. Currently used in Microsoft reference application [eShopOnWeb](https://github.com/dotnet-architecture/eShopOnWeb), which is the best place to see it in action, as well as the [Clean Architecture solution template](https://github.com/ardalis/cleanarchitecture). Check out Steve "ardalis" Smith's associated (free!) eBook, [Architecting Modern Web Applications with ASP.NET Core and Azure](https://aka.ms/webappebook), as well.
## Documentation
### [Read the Documentation](https://ardalis.github.io/Specification/)
## Releases
The change log for `version 9` and the list of breaking changes can be found [here](https://github.com/ardalis/Specification/issues/427).
## Sample Usage
The Specification pattern pulls query-specific logic out of other places in the application where it currently exists. For applications with minimal abstraction that use EF Core directly, the specification will eliminate `Where`, `Include`, `Select` and similar expressions from almost all places where they're being used. In applications that abstract database query logic behind a `Repository` abstraction, the specification will typically eliminate the need for many custom `Repository` implementation classes as well as custom query methods on `Repository` implementations. Instead of many different ways to filter and shape data using various methods, the same capability is achieved with few core methods.
Example implementation in your repository using specifications
```c#
public async Task> ListAsync(ISpecification specification, CancellationToken cancellationToken = default)
{
var query = SpecificationEvaluator.Default.GetQuery(_dbContext.Set(), specification);
return await query.ToListAsync(cancellationToken);
}
```
Now to use this method, the calling code simply instantiates and passes the appropriate specification.
```c#
var spec = new CustomerByNameSpec("customerName");
var customers = await _repository.ListAsync(spec, cancellationToken);
```
Specifications should be defined in an easily-discovered location in the application, so developers can easily reuse them. The use of this pattern helps to eliminate many commonly duplicated lambda expressions in applications, reducing bugs associated with this duplication.
We're shipping a built-in repository implementation [RepositoryBase](https://github.com/ardalis/Specification/blob/main/src/Ardalis.Specification.EntityFrameworkCore/RepositoryBaseOfT.cs), ready to be consumed in your apps. You can use it as a reference and create your own custom repository implementation.
## Reference
Some free video streams in which this package has been developed and discussed on [YouTube.com/ardalis](http://youtube.com/ardalis?sub_confirmation=1).
- [Reviewing the Specification Pattern and NuGet Package with guest Fiseni](https://www.youtube.com/watch?v=BgWWbBUWyig&t=315s&ab_channel=Ardalis) 6 Nov 2020
- [Open Source .NET Development with Specification and Other Projects](https://www.youtube.com/watch?v=zP_279p2D9w) 14 Jan 2020
- [Updating Specification and GuardClauses Nuget Packages / GitHub Samples](https://www.youtube.com/watch?v=kCeRJj2H1RQ) 20 Nov 2019
- [Ardalis - Working on the Ardalis.Specification and EF Extensions GitHub projects](https://www.youtube.com/watch?v=PbHic9Ndqoc) 16 Aug 2019
- [Working on the Ardalis.Specification Nuget Package and Integration Tests](https://www.youtube.com/watch?v=Ia3zb6-2LuY) 23 July 2019
Pluralsight resources:
- [Design Patterns Library - Specification](https://www.pluralsight.com/courses/patterns-library)
- [Domain-Driven Design Fundamentals](https://www.pluralsight.com/courses/domain-driven-design-fundamentals)
- [Specification Pattern in C#](https://www.pluralsight.com/courses/csharp-specification-pattern)