无法隐式转换类型&#39;System.Collections.Generic.List <System.Data.DataRow> &#39;到&#39;System.Collections.Generic.List <string> &#39;

Question

I have the following code:

   List<String> rows = 
     allDetails.Tables[3].AsEnumerable().OrderBy(dr => dr.Field<string>  ("JobTitle")).ToList();

The error is:

Cannot implicitly convert type 'System.Collections.Generic.List<System.Data.DataRow>' to 'System.Collections.Generic.List<string>'

Answer 1

DataTable.AsEnumerable() returns an IEnumerable<DataRow> which you can use for LINQ queries like yours. But you cannot use ToList on it and expect that it is a List<String> . Therefore you have to select the string-field:

List<String> orderedJobTitles = allDetails.Tables[3].AsEnumerable()
    .OrderBy(dr => dr.Field<string>("JobTitle"))
    .Select(dr => dr.Field<string>("JobTitle"))
    .ToList();

You could also select the field before you order by it if you don't need the DataRow anyway:

List<String> orderedJobTitles = allDetails.Tables[3].AsEnumerable()
    .Select(dr => dr.Field<string>("JobTitle"))
    .OrderBy(jobTitle => jobTitle)
    .ToList();