A Fluent API for defining queries. Allows fluent language based linq queries, and easy definition and consumption of Query Objects.

It all starts with the Query class. to begin a new query, just do the following:

Query<Book>

Then you select what you want to query against. If it's the entity itself, then you can use Is, if it's a property you can use Has(b => b.SomeProperty) and use a lambda expression to select the property. Finally select the predicate to resolve the query. For example:

Query<Book>.Is.EqualTo(otherBook); Query<Book>.Has(b => b.Author).NotEqualTo("Oscar Wilde"); Query<Book>.Has(b => b.Title).Containing("The"); Query<Book>.Has(b => b.Available).False(); Query<Book>.Has(b => b.Pages).GreaterThan(1000);

Obviously, a large amount of the time, we want to query more than one thing. You can chain queries together using And or Or:

Query<Book>.Is.EqualTo(otherBook).Or.Has(b => b.Author).NotEqualTo("Oscar Wilde"); Query<Book>.Has(b => b.Pages).GreaterThan(500).And.Has(b => b.Available).True();

Once you've defined your query you can compile to an Expression:

Query<Book>.Has(b.Title).EqualTo("The Picture of Dorian Gray").AsExpression(); Context.Books.Where(Query<Book>.Has(b.Title).EqualTo("The Picture of Dorian Gray").AsExpression()).ToList();

You can also check if any object satisfies a query, either by using the IsSatisfiedBy or the extension method Satisfies on an object.

var query = Query<Book>.Has(b.Title).StartingWith("The"); query.IsSatisfiedBy(aBook); anotherBook.Satisfies(query);

The idea of FluentQueries is to help the readability of LINQ queries. One way to do this is to utilise the FluentQueries framework to create classes that represent queries:

public class AuthorHasName : Query<Book> { public AuthorHasName(string firstName, string lastName) { Define( Has(b => b.Author) .EqualTo($"{firstName} {lastName}") ); } }

You now have a nice, explicit and reusable class for querying the authors name:

aBook.Satisfies(new AuthorHasName("Charles", "Dickens"));

Finally you can combine existing queries with new ones:

Query<Book>.Has(b => b.Pages).GreaterThan(1000).And.Is.Satisfying(new AuthorHasName("William", "Shakespeare"));

Or combine lambda expressions with queries:

Query<Book>.Has(b => b.Title).EndingWith("Wild").And.Has(b => b.Pages).Satisfying(p => p > 1000);

This means if there is anything not supported by FluentQueries you can still use a lambda expression combined with Queries.