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ASP.NET Try Catch throw new ArgumentException Not Working?

I have great success with ArgumentException and C# desktop apps, but not having any success with asp.net webforms. The 'FileImport' class is in the App_Code folder and called by another FileImport.aspx.cs.

* The 'LoadDataset' method analyzes the imported file column header names with a string of correctl names. It does error if the '.Equals' returns false, but the ArgumentException is:
1. Not sent to the FileImport.aspx.cs
- or -
2. Not caught correctly by the FileImport.aspx.cs.

- App_Code/FileImport.cs -

public DataTable LoadDataset(String path)
{
       if (!dbColumnNames.Equals(dtColumnNames))
       {
                return null;

                throw new ArgumentException("The Excel file columns are incorrect!");
       }
        return dt;
}


- FileImport.aspx.cs -

 protected void btnImport_Click(object sender, EventArgs e)
 {
        DataTable dt = new DataTable();
        FileImport fi = new FileImport(path);        
        try
        {
            dt = fi.LoadDataset(System.Web.HttpContext.Current.Server.MapPath("~/Uploads/" + fileName));
        }
        catch (ArgumentException ex)
        {
            ScriptManager.RegisterStartupScript(this, this.GetType(), "ServerControlScript", "alert(" + ex.Message + ");", true);
 }

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Daniel Van Der Werken

You're returning before you hit that line of code.
do this:

public DataTable LoadDataset(String path)
{
       dt = null;
       if (!dbColumnNames.Equals(dtColumnNames))
       {
                throw new ArgumentException("The Excel file columns are incorrect!");
       }
        return dt;
}

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or something like it. You are returning NULL before you hit the exception code.

WorknHardr

ASKER

Would this work too?
public DataTable LoadDataset(String path)
{
If(!dbColumnNames.Equals(dtColumnNames))
{
throw new ArgumentException("The Excel file columns are incorrect!");
}
}

Daniel Van Der Werken

The method returns a DataTable, so you need to do that somewhere within the method.

The key element here is that you make sure not to call the return before throwing the exception.

So, as written, the method you have would not even compile.

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WorknHardr

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WorknHardr

ASKER

Note: The problem with the Javascript 'Alert' is not enough ' ' like so:

System.Web.UI.ScriptManager.RegisterStartupScript(this, this.GetType(), "ServerControlScript", "alert( ' " + ex.Message + " ' );", true);

WorknHardr

ASKER

Sorry, found my own solution, thx