null-coalescing operator with wildcard in a lambda expression

tintyethan Published at Dev

tintyethan

I have a search form with multiple inputs - first name, last name, company...

I would like to return entities based on user inputs, or if nothing is input, in the last name field for instance, return all last names.

I believe I should be using null-coalescing for this, just like "ISNULL" in t-sql...

contacts = contacts.Where(s => s.firstname.ToUpper().Contains(fNameSearch.ToUpper() ?? *)

The issue is that I don't know how to use a wildcard in this type of experession.

For instance, this returns everything that contains "test" in the firstname property if fNameSearch is null or white-space...

 contacts = contacts.Where(s => s.firstname.ToUpper().Contains(fNameSearch.ToUpper() ?? "test")

but I want to be able to return everything, not just "test".

Douglas

If you want to return everything, can't you place the condition before the query?

var contacts = /* construct your original query here */
if (fNameSearch != null)
    contacts = contacts.Where(s => s.firstname.ToUpper().Contains(fNameSearch.ToUpper());

Edit: Per Steve's comment below, case-sensitivity depends on the database's collation (and is case-insensitive by default), so you can just run:

var contacts = /* construct your original query here */
if (fNameSearch != null)
    contacts = contacts.Where(s => s.firstname.Contains(fNameSearch));

Edit₂: If you have multiple inputs to check for, you can use the same approach compositionally:

var contacts = /* construct your original query here */
if (string.IsNullOrEmpty(fNameSearch) == false))
    contacts = contacts.Where(s => s.firstname.Contains(fNameSearch));
if (string.IsNullOrEmpty(fSurnameSearch) == false))
    contacts = contacts.Where(s => s.surname.Contains(fSurnameSearch));
if (string.IsNullOrEmpty(fCompanySearch) == false))
    contacts = contacts.Where(s => s.company.Contains(fCompanySearch));

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