Spectacular

This library is implementation of the Specification Design Pattern in C# language.

Expression has been used in this implementation. Thanks to Expression, developers can use Specification for querying database through libraries such as EntityFramework.

You can combine Specification classes through the And operator included as built-In. Via these operator, you can easily create your complex queries by combining smaller criteria.

For more information about the Specification Design Pattern, you can check the story on medium.

Platform	Status
Travis
GitHub

NuGet Package Name	Version
Spectacular

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Getting Started

Preparing custom specification via AbstractSpecification

public class GenderShould : AbstractSpecification<Person>
{
    private GenderShould(Genders gender)
        : base(person => person.Gender == gender)
    {
    }

    public static AbstractSpecification<Person> Be(Genders gender)
    {
        GenderShould genderShould = new(gender);
        return genderShould;
    }
    
    public static AbstractSpecification<Person> BeMale => Be(Genders.Male);
    public static AbstractSpecification<Person> BeFemale => Be(Genders.Female);
}

Checking whether an object satisfy the criteria :

Person person = new("adem", Genders.Male);

AbstractSpecification<Person> spec = GenderShould.BeMale;
bool isSatisfied = spec.IsSatisfiedBy(person);

Filtering the collection by criteria :

IQueryable<Person> personCollection = ...

AbstractSpecification<Person> spec = GenderShould.BeMale;
var filteredCollection = personCollection.Where(spec).ToList();

Combine criteria :

var ageCriteria = AgeShould.BeGreaterThan(18).And(AgeShould.BeLessThan(35));
SpecificationGroup<Person> specificationGroup = ageCriteria.And(GenderShould.BeFemale);

var filteredCollection = personCollection.Where(specificationGroup).ToList();