Get order in database, get this fail Unable to cast object of type 'System.Collections.Generic.List`1[ValgtFrugt]' to type 'System.Data.DataTable?

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Hi
When a user order some fruits, he gets to a new page were the inputs is standing. So the user can se what the user have been order and then he could do a confirmation with the contact information.

Before the user is insert the contact information, the user have a choice to make some other options to put to the order.

And when he click on the button the users order information, options and the fruit order could be in the database.

The bekraeft.aspx.cs

C#

public ValgtFrugt frugtKurv;
    public ValgtGroent groentKurv;
    public ValgtDeli deliKurv;
    protected void Page_Load(object sender, EventArgs e)
    {

        if (Session["ValgteFrugter"] != null)
        {
            List<ValgtFrugt> valgteFrugter = (List<ValgtFrugt>)Session["ValgteFrugter"];
            foreach (ValgtFrugt frugt in valgteFrugter)
            {
                //Variablen "frugt" indeholder nu hvert enkelt valgtfrugt objekt og nu kan du gøre sådan:
                Label1.Text += string.Format("{0} ({1} stk.)<br />", frugt.FrugtNavn, frugt.Antal);

            }
            List<ValgtGroent> valgteGroent = (List<ValgtGroent>)Session["ValgteGroent"];
            foreach (ValgtGroent groent in valgteGroent)
            {
                //Variablen "frugt" indeholder nu hvert enkelt valgtfrugt objekt og nu kan du gøre sådan:
                Label1.Text += string.Format("{0} ({1} stk.)<br />", groent.GroentNavn, groent.AntalGroent);

            }
           
        }
        else
        {
           Label1.Text = Session["standard"].ToString();
        }        
    }
    protected void Button_putikurv_Click(object sender, EventArgs e)
    {
        int totalvaerdi = 0;

        List<ValgtDeli> valgteDeli = new List<ValgtDeli>(); //Her laver jeg en liste over valgte frugter. Det er et nyt objekt, som kan indeholde påde ID, Navn, Antal og Værdi

        foreach (RepeaterItem item in VisDeli.Items)
        {
            if (item.ItemType == ListItemType.Item || item.ItemType == ListItemType.AlternatingItem)
            {
                    TextBox TextBox_deli = item.FindControl("TextBox_deli") as TextBox;



                    if (!string.IsNullOrEmpty(TextBox_deli.Text))
                    {

                        opretOrdre();

                    }

                string DeliNavn = TextBox_deli.Attributes["DeliNavn"]; //Det her skal vel være en streng!?

                if (TextBox_deli.Text != null)
                {

                    if (string.IsNullOrEmpty(TextBox_deli.Text))
                    {
                        TextBox_deli.Text = "0";

                    }
                }


                int enkeltDeliAntal = int.Parse(TextBox_deli.Text);


                totalvaerdi += (enkeltDeliAntal);


                if (enkeltDeliAntal > 0)
                {
                    ValgtDeli frugtenDerskalTilfoejes = new ValgtDeli(); //Opret frugten og angiv værdier
                    frugtenDerskalTilfoejes.DeliNavn = DeliNavn;
                    frugtenDerskalTilfoejes.Antal = enkeltDeliAntal;
                    valgteDeli.Add(frugtenDerskalTilfoejes);

                }

            }
            if (totalvaerdi > 0)
            {
                Session["ValgteDeli"] = valgteDeli;
                opretOrdre();
            }

        }
        
    }
    private void opretOrdre()
    {

        SqlConnection conn = new SqlConnection();
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();

        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;
        cmd.CommandText = "INSERT INTO ordre (dato, navn, efternavn, mobil, adresse, mail, postnr, bynavn) VALUES(GETDATE(), @navn, @efternavn, @mobil, @adresse, @mail, @postnr, @bynavn); SELECT SCOPE_IDENTITY()";

        cmd.Parameters.Add("@navn", SqlDbType.VarChar).Value = TextBox_navn.Text;
        cmd.Parameters.Add("@efternavn", SqlDbType.VarChar).Value = TextBox_efternavn.Text;
        cmd.Parameters.Add("@mobil", SqlDbType.VarChar).Value = TextBox_mobil.Text;
        cmd.Parameters.Add("@adresse", SqlDbType.VarChar).Value = TextBox_adresse.Text;
        cmd.Parameters.Add("@mail", SqlDbType.VarChar).Value = TextBox_mail.Text;
        cmd.Parameters.Add("@postnr", SqlDbType.VarChar).Value = TextBox_postnr.Text;
        cmd.Parameters.Add("@bynavn", SqlDbType.VarChar).Value = TextBox_by.Text;

        conn.Open();
        object orderId = cmd.ExecuteScalar();
        conn.Close();
        
        cmd.Parameters.Add("@fk_ordre", SqlDbType.Int).Value = orderId;
        cmd.Parameters.Add("@fk_frugt_id", SqlDbType.Int).Value = 0;
        cmd.Parameters.Add("@fk_deli_id", SqlDbType.Int).Value = 0;
        cmd.Parameters.Add("@fk_groent_id", SqlDbType.Int).Value = 0;
        cmd.Parameters.Add("@Antal", SqlDbType.Int).Value = 0;
        
        cmd.Parameters.Add("@frugt_id", SqlDbType.VarChar).Value = 0;
        cmd.Parameters.Add("@deli_id", SqlDbType.VarChar).Value = 0;
        cmd.Parameters.Add("@groent_id", SqlDbType.VarChar).Value = 0;

        DataTable dt = (DataTable)Session["ValgteFrugter"];
        DataTable dt1 = (DataTable)Session["ValgteGroent"];
        DataTable dt2 = (DataTable)Session["ValgteDeli"];
        
        DataTable dtAll = new DataTable();
        dtAll = dt.Copy();
        dtAll.Merge(dt1, true);
        dtAll.Merge(dt2, true);

                conn.Open();

        foreach (DataRow row in dtAll.Rows)
        {
            cmd.CommandText = @"INSERT INTO ordre_linie 
                                (fk_ordre_id, fk_frugt_id, fk_deli_id, fk_groent_id, antal) 
                                VALUES (@fk_ordre, @fk_frugt_id, @fk_deli_id, @fk_groent_id, @Antal)";

            cmd.Parameters["@fk_frugt_id"].Value = row["FrugtNavn"];
            cmd.Parameters["@fk_deli_id"].Value = row["DeliNavn"];
            cmd.Parameters["@fk_groent_id"].Value = row["GroentNavn"];
            cmd.Parameters["@Antal"].Value = row["Antal"];           

            cmd.ExecuteNonQuery();
        }
       
        conn.Close();
        Session.Abandon();
        Response.Redirect("tak.aspx");      
       
    }

    protected void VisDeli_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            TextBox TextBox_deli = e.Item.FindControl("TextBox_deli") as TextBox;

            if (TextBox_deli == null) return;

            TextBox_deli.Attributes.Add("DeliID", string.Format("{0}", ((DataRowView)(e.Item.DataItem)).Row["deli_id"])); //Læg en ny attribut på TextBoxen der peger på frugtens unikke ID.  
            TextBox_deli.Attributes.Add("DeliNavn", string.Format("{0}", ((DataRowView)(e.Item.DataItem))["deli_navn"])); //Læg en ny attribut på TextBoxen der peger på vaerdi.          
            
        }
    }

When I click on the button, I get this Error:

Unable to cast object of type 'System.Collections.Generic.List`1[ValgtFrugt]' to type 'System.Data.DataTable

Line 164:
Line 165:
Line 166: DataTable dt = (DataTable)Session["ValgteFrugter"];
Line 167: DataTable dt1 = (DataTable)Session["ValgteGroent"];
Line 168: DataTable dt2 = (DataTable)Session["ValgteDeli"];

Hope someone could help me?

/Tina

Posted 15-Oct-13 2:53am

tina_overgaard

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Comments

Ankur^\m/ 15-Oct-13 8:56am

The value you stored in the Session["ValgteFrugter"] is of type GenericList. While getting the value you are assigning it to a DataTable which is an invalid cast.

tina_overgaard 15-Oct-13 9:06am

How do I get the cast to a datatable? Or can I use the genericList to get the session information into database?

Ankur^\m/ 15-Oct-13 9:18am

Please see my answer.

1 solution

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Ankur^\m/ · Accepted Answer · 2013-10-15T03:08:00

Solution 1

The value you stored in the Session["ValgteFrugter"] is of type Generic List[^]. While getting the value you are assigning it to a DataTable which is an invalid cast.

You will have to convert it to a DataTable first. Extension method CopyToDataTable[^] may be useful or you may loop through the list manually to create a DataTable.

Posted 15-Oct-13 3:08am

Ankur^\m/

Updated 15-Oct-13 3:17am

v2

Comments

Ankur^\m/ 15-Oct-13 9:19am

You may also refer http://stackoverflow.com/questions/15004207/convert-generic-list-to-datatable-using-linq
which talks about how to convert generic list to a DataTable.

tina_overgaard 15-Oct-13 9:47am

Is it something like this:

var FrugtList = new List<valgtfrugt>();
var dataTable = new DataTable();

dataTable.Columns.Add("FrugtID", typeof(int));
dataTable.Columns.Add("FrugtNavn", typeof(string));
dataTable.Columns.Add("Antal", typeof(int));
dataTable.Columns.Add("FrugtVaerdi", typeof(int));

foreach (var FrugtList in ValgtFrugt)
{
dataTable.Rows.Add(ValgtFrugt.FrugtID, ValgtFrugt.FrugtNavn, ValgtFrugt.Antal, ValgtFrugt.FrugtVaerdi)
}

Ankur^\m/ 15-Oct-13 9:56am

Yes that should work. You don't need the first line [var FrugtList = new List();] though.

tina_overgaard 15-Oct-13 9:56am

How do I get all the datatable merge to one? I need a little more help

Ankur^\m/ 15-Oct-13 9:57am

Do all of them have same columns?

Ankur^\m/ 15-Oct-13 10:05am

DataTable does have a Merge() method - http://msdn.microsoft.com/en-us/library/system.data.datatable.merge.aspx

tina_overgaard 15-Oct-13 13:10pm

DataTable dt = (DataTable)Session["ValgteFrugter"];
DataTable dt1 = (DataTable)Session["ValgteGroent"];
DataTable dt2 = (DataTable)Session["ValgteDeli"];

DataTable dtAll = new DataTable();
dtAll = dt.Copy();
dtAll.Merge(dt1, true);
dtAll.Merge(dt2, true);

Like this?

Ankur^\m/ 15-Oct-13 13:51pm

Yes. Do open a sample project and test these there. Use debugger and a watch for the required values and you will be able to learn better.
:thumbsup:

tina_overgaard 15-Oct-13 14:35pm

I have tested my project, and it looks like its been done correct. But when the Debugging is going to where the order is put in to the database it is coming with this error

Input string was not in a correct format.
Line 210:
Line 211:
Line 212: cmd.ExecuteNonQuery();
Line 213: }

Where is the wrong input string?

tina_overgaard 15-Oct-13 14:35pm

List<valgtfrugt> valgteFrugter = (List<valgtfrugt>)Session["ValgteFrugter"];
var dataTable = new DataTable();

dataTable.Columns.Add("FrugtID", typeof(int));
dataTable.Columns.Add("FrugtNavn", typeof(string));
dataTable.Columns.Add("Antal", typeof(int));
dataTable.Columns.Add("FrugtVaerdi", typeof(int));

foreach (ValgtFrugt frugt in valgteFrugter)
{
dataTable.Rows.Add(frugt.FrugtID, frugt.FrugtNavn, frugt.Antal, frugt.FrugtVaerdi);
}

List<valgtgroent> valgteGroent = (List<valgtgroent>)Session["ValgteGroent"];
var dataTable1 = new DataTable();

dataTable1.Columns.Add("GroentID", typeof(int));
dataTable1.Columns.Add("GroentNavn", typeof(string));
dataTable1.Columns.Add("AntalGroent", typeof(int));
dataTable1.Columns.Add("FrugtVaerdi", typeof(int));

foreach (ValgtGroent groent in valgteGroent)
{
dataTable1.Rows.Add(groent.GroentID, groent.GroentNavn, groent.AntalGroent, groent.GroentVaerdi);
}
List<valgtdeli> valgteDeli = (List<valgtdeli>)Session["ValgteDeli"];
var dataTable2 = new DataTable();

dataTable2.Columns.Add("DeliID", typeof(int));
dataTable2.Columns.Add("DeliNavn", typeof(string));
dataTable2.Columns.Add("Antal", typeof(int));

foreach (ValgtDeli delikatesse in valgteDeli)
{
dataTable1.Rows.Add(delikatesse.DeliID, delikatesse.DeliNavn, delikatesse.Antal);
}

DataTable dtAll = new DataTable();
dtAll = dataTable.Copy();
dtAll.Merge(dataTable1, true);
dtAll.Merge(dataTable2, true);

conn.Open();

foreach (DataRow row in dtAll.Rows)
{
cmd.CommandText = @"INSERT INTO ordre_linie
(fk_ordre_id, fk_frugt_id, fk_deli_id, fk_groent_id, antal)
VALUES (@fk_ordre, @fk_frugt_id, @fk_deli_id, @fk_groent_id, @Antal)";

cmd.Parameters["@fk_frugt_id"].Value = row["FrugtNavn"].ToString();
cmd.Parameters["@fk_deli_id"].Value = row["DeliNavn"].ToString();
cmd.Parameters["@fk_groent_id"].Value = row["GroentNavn"].ToString();
cmd.Parameters["@Antal"].Value = row["Antal"].ToString();

cmd.ExecuteNonQuery();
}

conn.Close();
Session.Abandon();
Response.Redirect("tak.aspx");

Ankur^\m/ 16-Oct-13 1:14am

Input string was not in a correct format - This error is thrown when you try to convert something that is not in correct format. For ex- when you try to convert a string "foo" to integer, this error will be thrown. Some of our parameter doesn't have a correct value.

tina_overgaard 16-Oct-13 3:38am

I solved the wrong input string. But my datatable is empty, I Can figure out what I am doping wrong

tina_overgaard 15-Oct-13 14:57pm

Something is wrong with my datatable it is not returning the value from the sessions, so the datatable is empty