c# - LINQ to Entities does not recognize the method 'Int32 ToInt32(System.String)' method

Question

I checked online for some answers, and I understood that I cannot translate ToInt32 to T-SQL, and I need to use run my query in-memory first and then do the conversion, but I don't know how to apply it in my example. I have the query below, and it shows me the error message written in the title:

string[] parts = rvm.ZipCode.Split('-');
var list = results.OrderBy(b => 
  Math.Abs(Convert.ToInt32(parts[0]) - Convert.ToInt32(b.Zip))).Take(5).ToList();

Where results is another query that I applied earlier. Any idea how to solve it?

Answer 1

Calling AsEnumerable() will force it to do the ordering in memory:

var list = results.AsEnumerable().OrderBy(b => Math.Abs(Convert.ToInt32(parts[0]) - Convert.ToInt32(b.Zip))).Take(5).ToList();

This may be extremely ineficient though as the Take(5) will occur after the data has already been retrieved from the database, so you are fetching the entire result set into memory, sorting it an then discarding all but the top 5 records.