CODEWITHSUNDEEP
c#asp.netlinq
Sudha
Sudha

Reputation: 503

How to split a string in a datatable and add into new rows using Linq C#?

I am new to linq. I am using linq to get vlaues from datalist control and creating a datatable with that values. The datatable contains three columns. In that, sometimes the 'Answer' column is having a data which is comma separated. You can see the image of datatable with comma separated column

            DataTable SaveAnswer = clsSource.SetData();
            var df = from DataListItem dli in PollDataList.Items
                     let z = ((HiddenField)dli.FindControl("IDReqHiddenField")) 
                     let y = ((RadioButtonList)dli.FindControl("rdblstPollOptions"))
                     let v = ((CheckBoxList)dli.FindControl("CheckBoxListMultiplePollOptions"))
                     select new
                     {
                         PollId=z.Value,
                         Answered1 = y.SelectedValue,
                         Answered2=v.Items.Cast<ListItem>().Where(r=>r.Selected)
                     };
           var result = from p in df
                         select SavePollAnswer.LoadDataRow(
                            new object[] { 
                                p.PollId,p.Answered1+string.Join( ", ", p.Answered2 ),""
                            },
                            false);
            SavePollAnswer = result.CopyToDataTable();

And here is my design

<asp:DataList ID="PollDataList" runat="server"    CssClass="poll-preview">
        <ItemTemplate>
            <asp:HiddenField ID="PollIDReqHiddenField" Value='<%# Eval("PollID") %>' runat="server" Visible="false" />
            <asp:Label ID="lblReqQuestionNumber" runat="server" Text='<%# Eval("NoofPollQuestion") %>' Font-Bold="true"></asp:Label><br />
            <asp:Label ID="lblRequiredPollQusetion" runat="server" Text='<%# Eval("PollQuestions") %>' Font-Bold="false"></asp:Label>
            <asp:Label ID="lblReqNotification" runat="server" ForeColor="Red" CssClass='<%# Eval("PollReq") %>' Text="*" Font-Bold="true"></asp:Label>
            <asp:RadioButtonList ID="rdblstPollOptions" DataSource='<%# Eval("PollOptionsReq") %>' runat="server"></asp:RadioButtonList>
            <asp:CheckBoxList ID="CheckBoxListMultiplePollOptions" DataSource='<%# Eval("PollOptionsMul") %>'  runat="server" RepeatDirection="Vertical" RepeatColumns="1"></asp:CheckBoxList>
        </ItemTemplate>
    </asp:DataList>

But we want the datatable output like this Expected Output

Thanks in advance!

Upvotes: 1

Views: 1687

Answers (1)

Simon Buchan
Simon Buchan

Reputation: 13255

LINQ can get you partway by allowing you to nest from clauses in queries (simplifying the output a bit):

from DataListItem dli in PollDataList.Items
let z = ... // as in existing code
let y = ...
let v = ...
from checkbox in v.Items
where checkbox.Selected
select new [] { z.Value, checkbox.Value, "" }

Here you will get an output item for each selected checkbox in each poll item (your Answered2). But you also want an output row for the Answered1 value for each poll item, and here LINQ is less helpful. There are two ways you can do this, the quick and ugly way using Enumerable.Concat:

...
let v = ...
from answer in new [] { y.SelectedValue }.Concat(v.Items.Where(r => r.Selected)) // http://msdn.microsoft.com/en-us/library/bb302894.aspx
select new [] { z.Value, answer, "" }

Or the clearer and more general, but longer way, using yield to create an iterator method that gives you an item for all the answers:

from DataListItem item in PollDataList.Items
let z = ...
from answer in PollItemAnswers(item)
...
// outside the method containing the above
IEnumerable<object> PollItemAnswers(PollListItem item)
{
    var y = ...; // As in let statements
    var v = ...;
    yield return y.Value; // return the first answer
    foreach (var checkBox in v.Items)
        if (checkBox.Selected)
            yield return checkBox.Value; // return the other answers
}

And finally, if your final code don't have the items already separated (say, it was posted from a web form), you can use string.Split():

 yield return y.Value;
 foreach (var answer in value.Split(',')) // "a, b, c" -> "a", " b", " c"
     yield return answer.Trim(); // " b" -> "b"

As a final note, watch out for if your answers could contain ,! In general, using something like JSON to safely move value collections around (say from a file or another machine) will save you a lot of grief.

Upvotes: 0

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