Is there a way to make this linq2sql more DRY? - entity-framework-core

Question

I would like to remove repetitions in this paragraph of code. Is it possible to write a function to cleanup any table nvarchar columns with a specified array of strings (or characters)? That query will be executed with ef core at the end.
I tried VS2022 refactoring tool to Extract Method, but it's extracting the whole Where(). I would like to "build" the Replaces chain. Is that possible?
var request = GetRequestValuesFromApi();
var query = _context.Persons.AsQueryable();
if (!string.IsNullOrWhiteSpace(request.Firstname))
{
string firstname = request.Firstname.Replace("-", "").Replace(" ", "").Replace("’", "").Replace("'", "");
query = query.Where(x => EF.Functions.Collate(x.Firstname!, "binary_ai").Replace("-", "").Replace(" ", "").Replace("’", "").Replace("'", "").Contains(firstname));
}
if (!string.IsNullOrWhiteSpace(request.Lastname))
{
string lastname = request.Lastname.Replace("-", "").Replace(" ", "").Replace("’", "").Replace("'", "");
query = query.Where(x => EF.Functions.Collate(x.Lastname!, "binary_ai").Replace("-", "").Replace(" ", "").Replace("’", "").Replace("'", "").Contains(lastname));
}
// ...
var results = query.ToList();

Answer 1

If you are willing to use LINQKit, you can embed Expression variables in queries and have them expanded in place before the query is executed:
var query = _context.Persons.AsQueryable().AsExpandable();
Expression<Func<string,string>> FixNameEFn = (string name) => name.Replace("-", "").Replace(" ", "").Replace("’", "").Replace("'", "");
var FixNameFn = FixNameEFn.Compile();
if (!string.IsNullOrWhiteSpace(request.Firstname)) {
string firstname = FixNameFn(request.Firstname);
query = query.Where(x => FixNameEFn.Invoke(EF.Functions.Collate(x.Firstname!, "binary_ai")).Contains(firstname));
}
if (!string.IsNullOrWhiteSpace(request.Lastname)) {
string lastname = FixNameFn(request.Lastname);
query = query.Where(x => FixNameEFn.Invoke(EF.Functions.Collate(x.Lastname!, "binary_ai")).Contains(lastname));
}
You can do this without LINQKit, but it would involve pushing the special operations up into a custom Where method (e.g., like WhereNameContains) which then builds or modifies an Expression<Func<>> and uses it in a regular Where call. But this would allow you to remove the EF.Functions.Collate repetition as well.