Question

i have this query (linq to entity) :

var query = from p in dbContext.Students
                        where p.Type == "پیش ثبت نام" && p.Approved == false
                        select p;

and as you see, i want to select all students with above condition,then i want Convert Result to Array with this code :

string[] strNumbers = dbContext.Students.Where(p=>p.Type=="پیش ثبت نام" && p.Approved==false).ToArray();

but above code its’not working : “Cannot implicitly convert type ‘NoavaranModel.Student[]’ to ‘string[]'”
and when i use this code :

string[] strNumbers = dbContext.Students.Where(p=>p.Type=="پیش ثبت نام" && p.Approved==false).Cast<string>().ToArray();

i get this error : “Unable to cast the type ‘NoavaranModel.Student’ to type ‘System.String’. LINQ to Entities only supports casting Entity Data Model primitive types. “.

then i want to Pass strNumbers to below Methode :

Utility.SendMessageForStudents(strNumbers);

Thanks in your Advise.

Answer 1

You have to return the string instead of student object which where clause returns. You can select student number using select method. Suppose student has StudentNumber

string[] strNumbers = dbContext.Students.Where(p=>p.Type=="پیش ثبت نام" && p.Approved==false).Select(c=>c.StudentNumber).ToArray();