The method 'Equals' is not supported - subsonic

Question

public List<Health_Scheme_System.Employee> GetPenEmployeeTable()
{
Health_Scheme_System.Health_Scheme_SystemDB db = new Health_Scheme_System.Health_Scheme_SystemDB();
var x = (from c in db.Employees
where c.Pensioners.Equals (1)
select c);
return x.ToList();
}
//Selecting multiple columns from an HR view table together with the scheme name of scheme.
public List<EmployeesX> GetPensioners()
{
Health_Scheme_System.Health_Scheme_SystemDB db = new Health_Scheme_System.Health_Scheme_SystemDB();
List<Health_Scheme_System.EmployeeDirectory> listEmployeeView = GetPenEmployeeView();
List<Health_Scheme_System.Employee> listEmployeeTable = GetPenEmployeeTable();
List<Health_Scheme_System.Scheme> listSchemes = GetSchemes();
List<EmployeesX> listOfEmployees = new List<EmployeesX>();
//checking for comparision of getemployeeview to getemployee table and then to getschemes
//Then display the scheme name if they are similar.
for (int i = 0; i < listEmployeeView.Count; i++)
{
EmployeesX emp = new EmployeesX();
emp.ID_NO = listEmployeeView[i].ID_NO;
emp.FIRST_NAME = listEmployeeView[i].FIRST_NAME;
emp.LAST_NAME = listEmployeeView[i].LAST_NAME;
emp.LOCATION_CODE = listEmployeeView[i].LOCATION_CODE;
for (int j = 0; j < listEmployeeTable.Count; j++)
{
if (listEmployeeTable[j].EmployeeIDCard == listEmployeeView[i].ID_NO)
{
emp.Pensioners = listEmployeeTable[j].Pensioners;
for (int k = 0; k < listSchemes.Count; k++)
{
if (listEmployeeTable[j].SchemeID == listSchemes[k].SchemeID)
{
emp.SCHEME_NAME = listSchemes[k].Name;
emp.START_DATE = listEmployeeTable[j].StartSchemeDate;
}
}
}
}
listOfEmployees.Add(emp);
}
return listOfEmployees;
}
How can I make the same method with using .equals??

Answer 1

Have you tried this:
var x = (from c in db.Employees
where c.Pensioners == 1
select c)
Additional info:
If you use a method on an object in a linq query subsonic needs to know how to translate that into pur SQL code. That does not work by default and must be implemented for every known method on every supported type for every dataprovider (if differs from default implementation). So there is a bunch of work to do for subsonic.
A good starting point for knowning what's supported and what not is the TSqlFormatter class. Have a look at protected override Expression VisitMethodCall(MethodCallExpression m)
https://github.com/subsonic/SubSonic-3.0/blob/master/SubSonic.Core/Linq/Structure/TSqlFormatter.cs
There is already an implementation for Equals
else if (m.Method.Name == "Equals")
{
if (m.Method.IsStatic && m.Method.DeclaringType == typeof(object))
{
sb.Append("(");
this.Visit(m.Arguments[0]);
sb.Append(" = ");
this.Visit(m.Arguments[1]);
sb.Append(")");
return m;
}
else if (!m.Method.IsStatic && m.Arguments.Count == 1 && m.Arguments[0].Type == m.Object.Type)
{
sb.Append("(");
this.Visit(m.Object);
sb.Append(" = ");
this.Visit(m.Arguments[0]);
sb.Append(")");
return m;
}
else if (m.Method.IsStatic && m.Method.DeclaringType == typeof(string))
{
//Note: Not sure if this is best solution for fixing side issue with Issue #66
sb.Append("(");
this.Visit(m.Arguments[0]);
sb.Append(" = ");
this.Visit(m.Arguments[1]);
sb.Append(")");
return m;
}
}
I suppose Prnsioners is an integer type so you basically have to add another else if and recomplie subsonic.
This should work but I haven't tested it.
else if (!m.Method.IsStatic && m.Method.DeclaringType == typeof(int))
{
sb.Append("(");
this.Visit(m.Arguments[0]);
sb.Append(" = ");
this.Visit(m.Arguments[1]);
sb.Append(")");
return m;
}
(or you can try the == approach like in the example on the top).