Input string was not in the correct format C# ASP.NET

Question

I am new to programming and currently working on a C# asp.net website that populates Telerik RadComboBoxes from a database on_load.

I have a form that has 15+ ComboBoxes and when I select values from those ComboBoxes those ComboBox selections must be used to search through a really large table in my database. A gridView will display the returned data.

I have used the same format of code throughout the rest of my project and it works perfectly, But when I select an item from my "Location" DropDownBox to search through my database I get the error 'Input string was not in a correct format' and I cant figure out why

here is my Location.cs Class

region Properties

    [Key]
    public int LocationID { get; se; }
    [Column("Location")]
    public string LocationName { get; set; }
    private int? _ParentLocationID;
    [Column]
    public int? ParentLocationID
    {
        get
        {
            return _ParentLocationID;
        }
        set
        {
            if (value == 0)
            {
                _ParentLocationID = null;
            }
            else
            {
                _ParentLocationID = value;
            }
        }
    }

    [Column]
    public int SiteID { get; set; }
    [Column]
    public bool Active { get; set; }

region Method

    public static IEnumerable<Location> LoadActiveLocations(int siteID)
    {
        iThNkContext db = new iThNkContext();

        var LocationList = (from l in db.Locations
                                where(l.SiteID == siteID && l.Active == true)
                                orderby l.LocationID
                                select l).ToList();

        return LocationList;
    }

And here is the code I am using in my .aspx file

RadTreeView trvLocation = (RadTreeView)cboLocation.Controls[2].FindControl("trvLocation");
         if (trvLocation.SelectedValue != "")
         {
            var locationID = Convert.ToInt32(trvLocation.SelectedValue);  //Error
            predicates.Add(p => p.LocationID == locationID);
        }

On the //Error line is where I am getting the 'Input string was not in the correct format' error, any suggestions please. I cant understand why I am having this problem

thank you in advance

The error means that the string you're trying to parse an integer from doesn't actually contain a valid integer. Use Int.TryParse — Satpal
– Satpal, Commented Apr 16, 2013 at 10:31
put a breakpoint and see what you get in trvLocation.SelectedValue — Habib
– Habib, Commented Apr 16, 2013 at 10:31
Have you looked at what trvLocation.SelectedValue returns? What type and/or value? — John Willemse
– John Willemse, Commented Apr 16, 2013 at 10:32
What are you binding to the control ? i guess the value part of the RadTreeView is not convertible to int hence the error — V4Vendetta
– V4Vendetta, Commented Apr 16, 2013 at 10:39

ajakblackgoat · Accepted Answer · 2013-04-16 10:39:18Z

1

if you expect the locationID to be a number, make sure the the value for each items in the combobox can be converted to numbers. otherwise, even if you use tryparse, your page won't run correctly.

P/S: TryParse will only avoid the error and won't assign the selectedvalue to locationID, and hence, break you logic.

answered Apr 16, 2013 at 10:39

ajakblackgoat

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1 Comment

DGibbs Over a year ago

+1 for mentioning that TryParse wont actually fix the problem.

FastGeek · Accepted Answer · 2013-04-16 10:54:59Z

1

It looks like your LocationID is a nullable value - you cannot convert a null value to an Int32. You need to ensure that each value member bound to the drop down list is not a null value but is a valid integer.

answered Apr 16, 2013 at 10:54

FastGeek

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