如何从Mutliple CheckBoxList选择检索输出并将其放置在ASP.Net的电子邮件文本文件中

Question

In my ASP.Net/C# site, I have a page which acts as a form and records the user's information. The form then sends this information to an email, by way of a formatted text file in my App Data folder. All of the input appears in the email, however, when I test to select multiple checkbox items, only one selection appears -- here's the formatted text file code:

Customer Name:     ##CustName##
Phone Number:      ##PhoneNumber##
Service Address:   ##Address##
City/State:        ##lstCitySelect##
ZipCode:           ##ZipCode##

Service Type:      ##ServiceType##
Service Date:      ##ServiceDate##
Service Time:      ##ServiceTime##

And here's the code-behind of the form I'm using to process all this into the email:

protected void btnSubmit_Click(object sender, EventArgs e)
{
    if (Page.IsValid)
    {
        string fileName = Server.MapPath("~/App_Data/ScheduleForm.txt");
        string mailBody = File.ReadAllText(fileName);

        mailBody = mailBody.Replace("##CustName##", txtFirstName.Text + " " + txtLastName.Text);            
        mailBody = mailBody.Replace("##PhoneNumber##", txtPhone.Text);
        mailBody = mailBody.Replace("##Address##", txtAddress.Text);
        mailBody = mailBody.Replace("##lstCitySelect##", lstCitySelect.SelectedValue);
        mailBody = mailBody.Replace("##ZipCode##", txtZipCode.Text);
        mailBody = mailBody.Replace("##ServiceType##", chkServiceOption.SelectedValue);
        mailBody = mailBody.Replace("##ServiceDate##", txtDatePopulate.Text);
        mailBody = mailBody.Replace("##ServiceTime##", txtTimePopulate.Text);
        mailBody = mailBody.Replace("##Details##", txtDetails.Text);

        MailMessage myMessage = new MailMessage();
        myMessage.Subject = "Response from web site";
        myMessage.Body = mailBody;

        myMessage.From = new MailAddress("email@myemail.com", "From Sender");
        myMessage.To.Add(new MailAddress("email@myemail.com", "To Recipient"));

        SmtpClient mySmtpClient = new SmtpClient();
        mySmtpClient.Send(myMessage);

        Message.Visible = true;
        FormTable.Visible = false;
    }            
}

My issue is with the chkServiceOption CheckBoxList control not returning all selected instances of "checked boxes" in the email. I couldn't find a class to pull out the index of selected values. Can some please suggest what I can use or do to accomplish this? I've included screen shots of the form before submitting, and after it hits the email -- notice only one instance of a service is pulled.

Answer 1

From the documentation :

To determine the selected items in the CheckBoxList control, iterate through the Items collection and test the Selected property of each item in the collection.

So you have to do something like this:

var services = chkServiceOption.Items.Cast<ListItem>()
                                     .Where(c => c.Selected)
                                     .Select(c => c.Text);

var servicesStr = string.Join(", ", services);

This is just a LINQ-ification of the following loop:

string ret = "";

foreach(var item in checkbox.items)
{
    if(item.Selected)
    {
        if (ret.Length > 0)
        {
            ret += ", ";
        }

        ret += item.Text;
    }
}

The idea is that you have to loop through each of the items in the CheckBoxList , check whether they are selected, then add them to a collection. I chose a comma-separated string for my "collection" in this example since I figured that's what you'd want in your email, but you can see how it could be any other type of collection as well.

Edit:

This is just addressing a request in comments to explain the LINQ query.

There are four basic steps I took here. I'll just go over each.

1. chkServiceOption.Items : This is the same for the foreach as LINQ. I assume you understand where that's coming from.
2. .Cast<ListItem>() : Here's where we start doing interesting things. The ListItemCollection class only implements IEnumerable , not the IEnumerable<T> that's required for LINQ queries to run. Thus, we have to cast each element to be of type ListItem . Behind the scenes, this is basically just a foreach loop that iterates over the ListItemCollection and casts each element.
3. .Where(c => c.Selected) : Here's where we start using LINQ. We're now dealing with an IEnumerable<ListItem> , so we can run queries based on that knowledge. The code behind here loops through each element, then only returns the elements that pass the predicate. In our case, that means it only returns the ones where c.Selected , which is just a well-known syntactic shortcut for c.Selected == true .
4. .Select(c => c.Text) : Now we have only the elements that we want, but they're still all typed as ListItem which isn't particularly useful to users. We want the text of each ListItem (checkbox), so we loop through each item and select the value of the Text property.
5. string.Join : This isn't really LINQ-y either, but basically now we just want to put in a comma between each element so that it better-resembles a human-readable list.

Answer 2

The issue is that chkServiceType option can have multiple (or no) selected values, not just the one. Your code is looking for a single value when you need to iterate of the control's item collection to see if a child item is selected. I am a bit rusty on it but it should look something like:

   foreach(var item in checkbox.items)
   {
      if(item.Selected)
      {
          //Do Something
      }
   }

Answer 3

chkServiceOption.Items[0].Selected

chkServiceOption.Items[1].Selected

chkServiceOption.Items[2].Selected

chkServiceOption.Items[0].Text 

Examine those in the debugger or just append to email so you can see the values......

Answer 4

The semantics of chkServiceOption.SelectedValue suggest to me that it refers, in fact, to a singular value, which would explain the behaviour you're seeing. You'll probably need to loop through the items in the CheckBoxList and test whether each is checked. Try something like this:

string serviceOptionTxt = "";
for (int i = 0; i < chkServiceOption.Items.Count; i++)
{
    if (chkServiceOption.Items[i].Selected)
        serviceOptionTxt += chkServiceOption.Items[i].Value + " ";
        // Or possibly?
        //serviceOptionTxt += chkServiceOption.Items[i].Text + " ";
    }
}
mailBody = mailBody.Replace("##ServiceType##", serviceOptionTxt);