How to fix: conversion failed when converting the nvarchar value 'hex mec' to data type int.

Question

1.44/5 (2 votes)

See more:

The problem occurs when I run the page even though I am not getting any errors on .cs.
'Hex Mec' is the first CompanyName from Supplier table with a datatype varchar (even though the error says 'converting the nvarchar value'. I'm trying to Populate One Asp.net Dropdown based on Selection in Another Dropdown taken from this reference link

I have a lot of stack trace where the source error is instructing me to trace.
I'm also doing codes using datasettableadapters and would welcome anyone's suggestion (pleading, for this is a thesis I'm working on).

What I have tried:

I'm not a very good coder and would like to seek help in the simplest way. I have tried using parse but nothing seems to be working (the bold characters are where I think it's not working). I'm trying to Populate One Asp.net Dropdown based on Selection in Another Dropdown and my code is:

protected void ddSuppliers_SelectedIndexChanged(object sender, EventArgs e)
    {
        int SupplierID = Convert.ToInt32(ddSuppliers.SelectedValue);
        SqlConnection con = new SqlConnection(connString);
        con.Open();
        SqlCommand cmd = new SqlCommand("SELECT * FROM [dbo].[RawMaterialMF] WHERE SupplierID=@SupplierID", con);
        cmd.Parameters.Add("@SupplierID", SqlDbType.Int).Value = SupplierID;

        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        con.Close();
ddRawMats.DataTextField = "ItemName";
        ddRawMats.DataValueField = "ItemName"; 
        ddRawMats.DataBind();
        ddRawMats.Items.Insert(0, new ListItem("Select Raw Materials", "0"));

where this dropdown also appears in:

protected void btnProceed_Click(object sender, EventArgs e)
    {
        ddSuppliers.Enabled = false;
        mvPDetails.ActiveViewIndex = 0;

        //getting ItemID using the ItemName from the dropdown list
        DataSetTableAdapters.PurchaseDetailsTableAdapter datItem = new DataSetTableAdapters.PurchaseDetailsTableAdapter();
        DataTable tblPurchase = new DataTable();
        tblPurchase = datItem.GetDataByItem(ddRawMats.Text);
        int Item = Convert.ToInt32(tblPurchase.Rows[0]["ItemID"].ToString());

        //getting SupplierID
        DataSetTableAdapters.PurchaseDetailsTableAdapter datSuppliers = new DataSetTableAdapters.PurchaseDetailsTableAdapter();
        DataTable tblSuppliers = new DataTable();
        tblSuppliers = datSuppliers.GetDataBySupplier(ddSuppliers.SelectedValue);
        int Supplier = Convert.ToInt32(tblSuppliers.Rows[0]["SupplierID"].ToString());

        //getting Price using the ItemName from the dropdown
        DataSetTableAdapters.RawMaterialMF1TableAdapter datPrice = new DataSetTableAdapters.RawMaterialMF1TableAdapter();
        DataTable tblPrice = new DataTable();
        tblPrice = datPrice.GetDataByPrice(Item);
        int Price = Convert.ToInt32(tblPrice.Rows[0]["Price"]);
        int total = Price * Convert.ToInt32(txtQty.Text.ToString());

        double qty;
        qty = Convert.ToDouble(txtQty.Text);

        //
        DataSetTableAdapters.PurchaseDetailsTableAdapter datInsert = new DataSetTableAdapters.PurchaseDetailsTableAdapter();
        datInsert.InsertPDetails(null, Item, qty, total, txtRemarks.Text, Supplier);


        gvPurchase.DataBind();
    }

Posted 26-Oct-17 22:17pm

C I'm not Sharp

Updated 26-Oct-17 22:58pm

v2

Add a Solution

3 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Richard MacCutchan · Answer 1 · 2017-10-26T22:30:00

Solution 1

Exactly what value do you expect to get from trying to convert "Hex Mec" to an integer? It is obviously impossible for the computer to make any guesses as to what you want.

Posted 26-Oct-17 22:30pm

Richard MacCutchan

Comments

C I'm not Sharp 27-Oct-17 4:39am

It's ID, an int. It's from a dropdown with a datasource that shows the list of companynames in the Supplier table, but I don't know why and what code is getting "Hex Mec" only when it should be getting all the companynames.

Richard MacCutchan 27-Oct-17 4:48am

You cannot convert a string of alphabetic characters to an integer. Also in the line:
int Supplier = Convert.ToInt32(tblSuppliers.Rows[0]["SupplierID"].ToString()); and assuming that the SupplierId item is an integer, why are you converting it to a string just so you can convert it back to an integer?

OriginalGriff · Answer 2 · 2017-10-26T22:38:00

If your column is supposed to be an integer ID field, why are you converting it to a string, in order to convert it back to an integer?
And if it isn't an integer - and it isn't if the data in your table is "hex mec" - then it probably should be, so problems like this don't occur.

We can't say "do this" and fix the problem - it's too tightly bound to your data and data source, neither of which we have any access to.
So, its going to be up to you.
Put a breakpoint on the first line in the function, and run your code through the debugger. Then look at your code, and at your data and work out what should happen manually. Then single step each line checking that what you expected to happen is exactly what did. When it isn't, that's when you have a problem, and you can back-track (or run it again and look more closely) to find out why.

Sorry, but we can't do that for you - time for you to learn a new (and very, very useful) skill: debugging!

phil.o · Answer 3 · 2017-10-26T22:58:00

Solution 3

We cannot see how your are populating your DropDownList.
Generally, DropDownLists bound to a table need two informations: the key representing the selected value (a key because it must allow to retrieve a specific row in the table unambiguously), and the text used to display the selected value. These informations are controlled with DataValueField and DataTextField properties, respectively. So that when you select "Hex Mec" in the list, the value returned by the SelectedValue property is the primary key of the element in the database table.
You can see more on DropDownList usage on its reference page:
DropDownList Class[^]
Kindly.

Posted 26-Oct-17 22:58pm

phil.o

Comments

C I'm not Sharp 27-Oct-17 5:25am

This is what's in my aspx page.
<asp:DropDownList ID="ddSuppliers" runat="server" Width="100%" CssClass="form-control" DataSourceID="SqlDataSourceSuppliers" DataTextField="CompanyName" DataValueField="CompanyName" AutoPostBack="True" OnSelectedIndexChanged="ddSuppliers_SelectedIndexChanged">

<asp:SqlDataSource runat="server" ID="SqlDataSourceSuppliers" ConnectionString='<%$ ConnectionStrings:CECnewConnectionString %>' SelectCommand="SELECT [CompanyName], [SupplierID] FROM Supplier">

I haven't had the chance to select anything bec first of all, it's directing me to an error page. T

phil.o 27-Oct-17 6:04am

Probably:

<asp:DropDownList ID="ddSuppliers" runat="server" Width="100%" CssClass="form-control" DataSourceID="SqlDataSourceSuppliers" DataTextField="CompanyName" DataValueField="SupplierID" AutoPostBack="True" OnSelectedIndexChanged="ddSuppliers_SelectedIndexChanged">