Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)'

Question

i have faced one error working with grid view column wise searching facility. here i have multiple column with varchar,int and nullable so. i make one helper method like FilterColumn that takes two arguments (ColumnName,SearchText). now i faced one problem when filtering with int values.

here is that method :

public static class Helper
{
    public static IQueryable<T> FilterForColumn<T>(this IQueryable<T> queryable, string colName, string searchText)
    {
        if (colName != null && searchText != null)
        {
            var parameter = Expression.Parameter(typeof(T), "m");
            var propertyExpression = Expression.Property(parameter, colName);
            System.Linq.Expressions.ConstantExpression searchExpression = null;
            System.Reflection.MethodInfo containsMethod = null;
            // this must be of type Expression to accept different type of expressions
            // i.e. BinaryExpression, MethodCallExpression, ...
            System.Linq.Expressions.Expression body = null;
            Expression ex1 = null;
            Expression ex2 = null;
            Expression converted = null;
            switch (colName)
            {
                // section for int properties
                case "party_id":
                case "type_id":
                case "status_id":
                case "category_id":  //here problem occurs
                    Int32 _int = Convert.ToInt32(searchText);
                    searchExpression = Expression.Constant(_int);
                    containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
                    body = Expression.Call(propertyExpression, containsMethod, searchExpression);
                    break;
                // section for int? properties
                case "country_id":
                case "state_id":
                    Int32? _int1 = Convert.ToInt32(searchText);
                    searchExpression = Expression.Constant(_int1);
                    converted = Expression.Convert(searchExpression, typeof(object));
                    containsMethod = typeof(Int32?).GetMethod("Equals", new[] { typeof(Int32?) });
                    body = Expression.Call(propertyExpression, containsMethod, converted);
                    break;
                // section for DateTime? properties
                case "PublishDate":
                case "Birth_date":
                case "Anniversary_date":
                case "Profile_Updated_datetime":
                case "CompletedOn":
                    DateTime currentDate = DateTime.ParseExact(searchText, "dd/MM/yyyy", null);
                    DateTime nextDate = currentDate.AddDays(1);
                    ex1 = Expression.GreaterThanOrEqual(propertyExpression, Expression.Constant(currentDate, typeof(DateTime?)));
                    ex2 = Expression.LessThan(propertyExpression, Expression.Constant(nextDate, typeof(DateTime?)));
                    body = Expression.AndAlso(ex1, ex2);
                    break;
                // section for DateTime properties
                case "Created_date":
                case "Register_Date":
                    DateTime currentDate1 = DateTime.ParseExact(searchText, "dd/MM/yyyy", null);
                    DateTime nextDate1 = currentDate1.AddDays(1);
                    ex1 = Expression.GreaterThanOrEqual(propertyExpression, Expression.Constant(currentDate1));
                    ex2 = Expression.LessThan(propertyExpression, Expression.Constant(nextDate1));
                    body = Expression.AndAlso(ex1, ex2);
                    break;
                default:
                    searchExpression = Expression.Constant(searchText);
                    containsMethod = typeof(string).GetMethod("Contains", new[] { typeof(string) });
                    body = Expression.Call(propertyExpression, containsMethod, searchExpression);
                    break;
            }
            var predicate = Expression.Lambda<Func<T, bool>>(body, new[] { parameter });
            return queryable.Where(predicate);
        }
        else
        {
            return queryable;
        }
    }
}

and here is my search button code how i pass column value and search values to FillGrid :

protected void btnsearch_Click(object sender, System.EventArgs e)
    {
        if (DDL_Column_List.SelectedItem.Value.Equals("19"))
        {
            RegularExpressionValidator5.Enabled = true;
        }
      if (Page.IsValid)
        {
            using (DataClassesDataContext db = new DataClassesDataContext())
            {
                System.Threading.Thread.Sleep(2000);
                if (DDL_Column_List.SelectedItem.Value != "-1" && txtsearch.Text.Trim() != "")
                {
                    switch (DDL_Column_List.SelectedItem.Text.ToString())
                    {
                        case "Name":
                            Session["ColumnName"] = "Name";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Type":
                            Session["ColumnName"] = "type_id";
                            Session["SearchText"] = db.PartyTypes.Where(t => t.typename.Contains(txtsearch.Text.Trim())).Select(t => t.Id).SingleOrDefault().ToString();
                            break;
                        case "Owner Name":
                            Session["ColumnName"] = "Ownername";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Owner Mobile":
                            Session["ColumnName"] = "Ownermob";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Contact Person Name":
                            Session["ColumnName"] = "ContactPerson";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Contact Person Mobile":
                            Session["ColumnName"] = "ContactPersonmob";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Phone":
                            Session["ColumnName"] = "Phone";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Mobile":
                            Session["ColumnName"] = "Mobile";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Room":
                            Session["ColumnName"] = "Room";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Building":
                            Session["ColumnName"] = "Build";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Road":
                            Session["ColumnName"] = "Road";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Area":
                            Session["ColumnName"] = "Area";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "City":
                            Session["ColumnName"] = "City";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Country":
                            Session["ColumnName"] = "country_id";
                            Session["SearchText"] = db.Countries.Where(c => c.Country_name.Equals(txtsearch.Text.Trim())).Select(c => c.Id).SingleOrDefault().ToString();
                            break;
                        case "State":
                            Session["ColumnName"] = "state_id";
                            Session["SearchText"] = db.States.Where(s => s.state_name.Equals(txtsearch.Text.Trim())).Select(s => s.Id).SingleOrDefault().ToString();
                            break;
                        case "Email":
                            Session["ColumnName"] = "Email";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Remark":
                            Session["ColumnName"] = "Remark";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Username":
                            Session["ColumnName"] = "Username";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                        case "Register Date":
                            Session["ColumnName"] = "Register_Date";
                            Session["SearchText"] = txtsearch.Text.Trim();
                            break;
                    }
                }
                else
                {
                    Session["SearchText"] = null;
                    Session["ColumnName"] = null;
                }
                this.FillGrid((String)Session["StartAlpha"] ?? null, (int)Session["GroupByENTYPE"] , (String)Session["ColumnName"] ?? null, (String)Session["SearchText"] ?? null);
                UpdatePanel10.Update();
                MPE.Show();
            }
        }
    }

here i faced one issue when working with int value when user types some string values like 'Customer' then i have to find out which id belongs to this text and i pass this id to session and then my helper method filtering it. now i have problem at type_id case. here one error throwing like :

Server Error in '/CRM' Application.

Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)'

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentException: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)'

Source Error: 


Line 42:                     converted = Expression.Convert(searchExpression, typeof(object));
Line 43:                     containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
Line 44:                     body = Expression.Call(propertyExpression, containsMethod, searchExpression);
Line 45:                     break;
Line 46:                 case "country_id":

Source File: f:\CRM\App_Code\Helper.cs    Line: 44 

Stack Trace: 


[ArgumentException: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)']
   System.Linq.Expressions.Expression.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arg, ParameterInfo pi) +4189655
   System.Linq.Expressions.Expression.ValidateArgumentTypes(MethodBase method, ExpressionType nodeKind, ReadOnlyCollection`1& arguments) +132
   System.Linq.Expressions.Expression.Call(Expression instance, MethodInfo method, IEnumerable`1 arguments) +71
   System.Linq.Expressions.Expression.Call(Expression instance, MethodInfo method, Expression[] arguments) +29
   Helper.FilterForColumn(IQueryable`1 queryable, String colName, String searchText) in f:\CRM\App_Code\Helper.cs:44
   Staff_Raise_Ticket.FillGrid(String StartAlpha, Int32 GroupByENTYPE, String ColumnName, String SearchText) in f:\CRM\Staff\Raise_Ticket.aspx.cs:249
   Staff_Raise_Ticket.btnsearch_Click(Object sender, EventArgs e) in f:\CRM\Staff\Raise_Ticket.aspx.cs:1342
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1

and i don't understand what going wrong here....

Answer 1

The code in your error does not match the code for you Helper method. The error reports this:

    converted = Expression.Convert(searchExpression, typeof(object));
    containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
    body = Expression.Call(propertyExpression, containsMethod, searchExpression);
    break;
case "country_id":

When I search your code for case "country_id": , I find these lines:

case "category_id":  //here problem occurs
    Int32 _int = Convert.ToInt32(searchText);
    searchExpression = Expression.Constant(_int);
    containsMethod = typeof(Int32).GetMethod("Equals", new[] { typeof(Int32) });
    body = Expression.Call(propertyExpression, containsMethod, searchExpression);
    break;
// section for int? properties
case "country_id":

The first line of code reported in the error

converted = Expression.Convert(searchExpression, typeof(object));

does not appear in the code you posted and is likely the source of the error: you're trying to call a method that expects an Int32 parameter with an object parameter, because you're converting searchExpression (which likely already has the correct type, Int32 ) to type object . Make sure the code you're looking at is the code being executed, and remove the conversion to object.