ExpressionAggregator 1.0.0

Expression Aggregator (GitHub)

Linq Expression aggregation, given list of Expressions it creates aggregated expression or Func. This is useful if you conditionally added expressions to a list of expressions and want to aggregated them all together into one expression or Func.

Interface:

public interface IExpressionAggregator<T>
{
    Func<T, bool> AggregateAndCompile(IEnumerable<Expression<Func<T, bool>>> list);
    
    Expression<Func<T, bool>> Aggregate(IEnumerable<Expression<Func<T, bool>>> list);
}

Sample code:

// accumulator by defualt is "And"
var list = new List<Expression<Func<Person, bool>>>();

// add expressions
list.Add(x => x.Age > 10);
list.Add(x => x.DateOfBirth > DateTime.MinValue);

// create sample size
var people = _fixture.CreateMany<Person>();

// aggregate expressions into one large expression and compile expression to Func
var func =_aggregator.AggregateAndCompile(list);

// use the Func is Linq Where clause
var filteredPeople = people.Where(func).ToList());

Extras:

This utility comes with ExpressionList class that is optional to use but it implements IList and overrides Add method and prevents adding expressions to the list if expression has constant value of null.

var list = new ExpressionList<Person>();

// this will be added successfully to the list
list.AddIfNotNull(x => x.FirstName == "Test firstname");

// this will not be added to the list
list.AddIfNotNull(x => x.NullableDateOfBirth == null);