IncludeStringEvaluator.cs

namespace Ardalis.Specification.EntityFrameworkCore;

public sealed class IncludeStringEvaluator : IEvaluator
{
    private IncludeStringEvaluator() { }
    public static IncludeStringEvaluator Instance { get; } = new();

    public bool IsCriteriaEvaluator => false;

    /// <inheritdoc/>
    public IQueryable<T> GetQuery<T>(IQueryable<T> query, ISpecification<T> specification) where T : class
    {
        if (specification is Specification<T> spec)
        {
            if (spec.OneOrManyIncludeStrings.IsEmpty) return query;
            if (spec.OneOrManyIncludeStrings.SingleOrDefault is { } includeString)
            {
                return query.Include(includeString);
            }
        }

        foreach (var includeString in specification.IncludeStrings)
        {
            query = query.Include(includeString);
        }

        return query;
    }
}