Problem Occuring at the time of fetching data from the LINQ query and Display into textbox..

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i have a one web form.in this form i put one text box ,drop down list and one grid view. In gridview there is template field as a Linkbutton (Command Name="view"). so when I click On view button then selected data will be display on text box and dropdown list..
Iam writing following code on gridview row command Event But Still it Display Error. .

C#

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
      
        DataClassesDataContext db = new DataClassesDataContext();
        db.Connection.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["Cn"].ConnectionString;
        if (e.CommandName == "view")
        {
            int StateId = Convert.ToInt32(e.CommandArgument);
            HiddenField1.Value = StateId.ToString();
            var state =
                (
                    from s in db.tblStates
                    where (s.Stateid == Convert.ToInt32(e.CommandArgument))
                    select new
                    {
                        s.StateName,
                        s.Countryid
                    }
                 ).FirstOrDefault();
            if (state != null)
            {
                TextBox1.Text = state.StateName;
                DropDownList1.SelectedValue = state.Countryid;
            }
                         
        }
    }

It Display Follwing Error..

C#

 System.InvalidCastException: Unable to cast object of type 'System.Int32' to type 'System.String'.

Source Error: 


Line 78:             int StateId = Convert.ToInt32(e.CommandArgument);
Line 79:             HiddenField1.Value = StateId.ToString();
Line 80:             var state =
Line 81:                 (
Line 82:                     from s in db.tblStates

Thanx

Posted 22-Feb-13 0:27am

Hidayat Meman

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Comments

Orcun Iyigun 22-Feb-13 7:00am

During debugging your code have you checked if the value is null or a character or not?

2 solutions

Solution 1

problem lies in
(s.Stateid == Convert.ToInt32(e.CommandArgument))
linq does not support conveting to int while fetching data

try this,

where (s.Stateid ==StateId)

Posted 22-Feb-13 1:01am

Taha Akhtar

Comments

Hidayat Meman 22-Feb-13 7:13am

thanx @akhtar..
but its not a problam.
problem is here
var state =
(
from s in db.tblStates
where (s.Stateid == Convert.ToInt32(e.CommandArgument))
select new
{
s.StateName,
s.Countryid
}
).FirstOrDefault();

Hidayat Meman 22-Feb-13 7:14am

first time state becomes null and above error will be display

Taha Akhtar 22-Feb-13 7:21am

I think first check your command argument value,it will be numeric,and 2nd above solution, did you try replcaing where

Hidayat Meman 22-Feb-13 7:38am

command argument value also integer and also try your 2nd way. i try to code another way check it... its correct or not ? ??

var state =
from s in db.tblStates
where (s.Stateid == StateId)
select s;
foreach (tblState st in state)
{
TextBox1.Text = st.StateName;
DropDownList1.SelectedValue = st.Countryid;
}

//it also display same error

Taha Akhtar 22-Feb-13 7:47am

what is the value of st.Countryid

Taha Akhtar 22-Feb-13 7:49am

attach debugger check that your dropdownlist have value of st.Countryid

Hidayat Meman 22-Feb-13 7:53am

but it does'nt enter within a loop.. error will be display at the time of checking condition first time and InvalidCastException terminate the execution

Taha Akhtar 22-Feb-13 7:56am

type of stateid?

Hidayat Meman 22-Feb-13 8:01am

its integer and its value is also correct

Hidayat Meman 22-Feb-13 8:02am

but s.Stateid does not have any value

Taha Akhtar 22-Feb-13 8:04am

try this db.tblStates.Where(s=>s.Stateid==StateId).FirstorDedefault;

Hidayat Meman 22-Feb-13 8:08am

ok i will try

Hidayat Meman 22-Feb-13 8:13am

i am writing query like this
var state =
db.tblStates.Where(s => s.Stateid== StateId).FirstOrDefault();
but it also display same error..

Hidayat Meman 22-Feb-13 8:05am

can i store the data into datatable which is into the state of LINQ query?

Taha Akhtar 22-Feb-13 8:09am

i thnk we are missing something.what are the values of db.tblStates?

Hidayat Meman 22-Feb-13 8:20am

db.tblState becomes NULL

Taha Akhtar 22-Feb-13 8:30am

first fill the table then query

Hidayat Meman 22-Feb-13 8:32am

thanx dude....

Hidayat Meman 22-Feb-13 8:30am

thankyou so much @Taha. problem has been solved

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Taha Akhtar · Accepted Answer · 2013-02-22T01:20:00

Solution 2

I think first check your command argument value,it will be numberic,and 2nd above solution

Posted 22-Feb-13 1:20am

Taha Akhtar