如何简化和优化此 lambda 表达式？

Question

I'm trying to simplify and optimize the following lambda expression. My requirement is to get the first lead whose mobile phone or telephone1 matches intakePhoneNum. I want to match first 10 digits only.

 Entity matchingLead = 
     allLeads.Where(l => 
         (l.Attributes.Contains("mobilephone") && 
         (Regex.Replace(l.Attributes["mobilephone"].ToString(), "[^0-9]", "").Length >=10 
             ? Regex.Replace(l.Attributes["mobilephone"].ToString(), "[^0-9]", "").Substring(0,9) 
             : Regex.Replace(l.Attributes["mobilephone"].ToString(), "[^0-9]", "").Substring(0)).Equals(intakePhoneNum))||
         (l.Attributes.Contains("address1_telephone1") && 
         (Regex.Replace(l.Attributes["address1_telephone1"].ToString(), "[^0-9]", "").Length >= 10 
             ? Regex.Replace(l.Attributes["address1_telephone1"].ToString(), "[^0-9]", "").Substring(0, 9) 
             : Regex.Replace(l.Attributes["address1_telephone1"].ToString(), "[^0-9]", "").Substring(0)).Equals(intakePhoneNum))).FirstOrDefault();

Answer 1

First, I would suggest to introduce variables for the attributes. Then, instead of the differentiation between Length >= 10 and Length < 10, simple use StartsWith. And last, instead of Where(...).FirstOrDefault, simply use FirstOrDefault(...)

Entity matchingLead = 
 allLeads.FirstOrDefault(l => 
 {
    if (l.Attributes.Contains("mobilephone"))
    {
        var phone = Regex.Replace(l.Attributes["mobilephone"].ToString(), "[^0-9]", "");
        if (phone.StartsWith(intakePhoneNum))
            return true;
    }
    if (l.Attributes.Contains("address1_telephone1"))
    {
        var phone = Regex.Replace(l.Attributes["address1_telephone1"].ToString(), "[^0-9]", "");
        if (phone.StartsWith(intakePhoneNum))
            return true;
    }
    return false;
 });