Using DataGrid to Update Database using LINQ in a WPF aaplication.

Question

0.00/5 (No votes)

See more:

Hello,
I have a DataGrid with three fields and also a Checkbox. On the check of the Checkbox, i want to update the DataBase. I have tried doing it. But the values are not reflecting in the database. The table to which am updating the data has no primary key. Will it also matter??

Here is the Code.

C#

private void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    using (DataClasses1DataContext context = new DataClasses1DataContext())
    {

        DataGridCellInfo defect = DataGrid.SelectedCells[0];

        string value = ((TextBlock)defect.Column.GetCellContent(defect.Item)).Text;

        int DefectID = Convert.ToInt32(value);

        var updateStatus = (from maintain in context.MaintenanceDefects
                            where maintain.DefectID == DefectID
                                select maintain).ToList();

         foreach (var pvalue in updateStatus)
        {
            System.Console.WriteLine(updateStatus[0].DefectStatus);
            System.Console.WriteLine(updateStatus[0].DefectID);
            System.Console.WriteLine(updateStatus[0].MaintenanceID);

            updateStatus[0].DefectStatus = "Fixed";

            context.SubmitChanges();

        }
    }
}

Kindly suggest the solution.

Thanks & regards
raj_arenem

Posted 27-Mar-13 21:18pm

raj_arenem

Updated 28-Mar-13 0:09am

v4

Add a Solution

Comments

Jegan Thiyagesan 28-Mar-13 6:06am

Why are you going through the foreach loop but selecting only the first item in the updateStatus collection?

raj_arenem 28-Mar-13 6:08am

Thank you for your reply.
I tried the other way also, but the result is the same.

1 solution

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)

J van Rooyen · Answer 1 · 2013-03-27T23:28:00

Solution 1

I had a quick look. I think the problem is in the foreach loop:

C#

foreach (var pvalue in updateStatus)
 {
 System.Console.WriteLine(updateStatus[0].DefectStatus);
 System.Console.WriteLine(updateStatus[0].DefectID);
 System.Console.WriteLine(updateStatus[0].MaintenanceID);

 updateStatus[0].DefectStatus = "Fixed";

 context.SubmitChanges();

 }

Its not updating DefectStatus because the foreach loop isn't triggering. Ensure there's data in the list variable named updateStatus before the list executes. Try something like:

C#

if (updateStatus.Count == 0) //Might be: (updateStatus.Count() == 0)
{
  //Throw no data exception and handle it
}

for (int i = 0; i < updateStatus.Count; i++)
{
   //Do work here and submit
}

Posted 27-Mar-13 23:28pm

J van Rooyen

Updated 27-Mar-13 23:29pm

v2

Comments

raj_arenem 28-Mar-13 6:05am

Thank you for your reply.
I checked that, it has data. The thing is it is not getting updated to the database. i would like to mention this, the table to which am updating has no primary key in it. Does this also matter?

Thanks & regards
raj_arenem

J van Rooyen 28-Mar-13 6:42am

It shouldn't, as long as there are unique identifiers.

Because LINQ needs the Object Model to be selected from the DB, and not cast or created on the fly. In other words, you need to select the object first, like so:

//Use the following code and replace all code in foreach loop
System.Console.WriteLine(updateStatus[0].DefectStatus);
System.Console.WriteLine(updateStatus[0].DefectID);
System.Console.WriteLine(updateStatus[0].MaintenanceID);

//Select a single (and DB bound/linked item)
MaintenanceDefect updateItem = context.MaintenanceDefects.Single(o => o.DefectID == pvalue.DefectID); //May need to parse or cast a few Int's there, depending on your design

//Update a field/property value
updateItem.DefectStatus = "Fixed";

//Update all objects bound/linked to the context
context.SubmitChanges();