LINQfriendly

LINQfriendly is a term used in software development to describe APIs, data structures, or libraries that are designed to be easily queried using Language-Integrated Query (LINQ) in the .NET framework. A LINQfriendly component presents data in a way that aligns with LINQ conventions, enabling developers to compose queries using standard operators such as Where, Select, OrderBy, GroupBy, and Join.

Core characteristics include exposing sequences as IQueryable<T> or IEnumerable<T>, supporting deferred execution, and avoiding side effects that disrupt query composition. A LINQfriendly API typically provides transparent mapping between domain objects and queryable representations, uses stable property accessors, and preserves queryable behavior across layers. It aims to keep query logic outside of imperative data access code, so queries can be built up incrementally and tested in isolation.

Benefits include reduced boilerplate, improved composability, better testability, and the ability for query providers to translate operations to the underlying data source (e.g., SQL). It is common in data access layers, repositories, and read models, where consistent query behavior across boundaries is desired. Potential drawbacks include the risk of inefficient translations, over-fetching, or exposing implementation details that hinder optimization.

Design considerations emphasize ensuring that expression trees in queries can be translated by the provider, avoiding client-side evaluation, and documenting which parts of a query can be translated. Related concepts include IQueryable-based repositories and LINQ-capable data sources, which are frequently discussed in .NET design guidance and used to ensure seamless integration with LINQ.