c# - Linq代码重构

Question

请帮助我使用 Linq 重构这段代码。如何只使用一次 Where 和 ToList？ 感谢帮助

private IEnumerable<SomeClass> Filter(IEnumerable<SomeClass> aaa, string name, string company, string address,int? age)       
{
    var ans = new List<SomeClass>();         
    if (!String.IsNullOrEmpty(name))
        ans = aaa.Where(x => x.name.equal(name)).ToList();

    if (!String.IsNullOrEmpty(company))
        ans = ans.Where(x => x.company.equal(company)).ToList();

    if (!String.IsNullOrEmpty(address))
        ans = ans.Where(x => x.address.equal(address)).ToList();

    if (age.HasValue)
        ans = ans.Where(x => x.age == age.Value).ToList();

    return ans;
}

Answer 1

你可以使用这个:

var ans = aaa.Where( x => ( string.IsNullOrEmpty(name)
                            || x.name.equal(name)
                          )
                          &&
                          ( string.IsNullOrEmpty(company)
                            || x.company.equal(company)
                          )
                          &&
                          ( string.IsNullOrEmpty(address)
                            || x.address.equal(address)
                          )
                          &&
                          ( !age.HasValue
                            || x.age == age.Value
                          )
                   );