Specification

Specification is a .NET library that implements the Specification pattern to encapsulate query logic into reusable, composable objects. Its primary goal is to pull filtering, sorting, and projection logic out of repositories and services, reducing duplication and improving maintainability. The library works especially well with Entity Framework Core, enabling developers to centralize query definitions instead of scattering LINQ expressions throughout the codebase. By defining specifications as classes, teams can build complex query rules that remain testable and easy to reason about. The project is used in Microsoft’s reference application eShopOnWeb and aligns closely with clean architecture principles. Overall, Specification provides a structured approach to query reuse and domain-focused data access in modern .NET applications.