C# csv helper save infomation

Question

0.00/5 (No votes)

See more:

I can write a new .csv file when the app opens but if I want to edit a existing .csv file and rewrite it I get a blank datagride. how do I get around that?

What I have tried:

C#

       private void btnWrite_Click(object sender, EventArgs e)
        {
           

                using (SaveFileDialog sfd = new SaveFileDialog() { Filter = "csv|*.csv", ValidateNames = true })
                {
                    if (sfd.ShowDialog() == DialogResult.OK)
                    {
                        using (var sw = new StreamWriter(sfd.FileName))
                        {
                            var writer = new CsvWriter(sw);
                            writer.WriteHeader(typeof(Lunch));

                            if (lunchBindingSource == null || lunchBindingSource.DataSource == null)
                            {
                                MessageBox.Show("Error in Saving.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
                                return;
                            }


                            foreach (Lunch s in lunchBindingSource.DataSource as List<Lunch>)
                            {
                                writer.WriteRecord(s);
                            }
                        }
                        MessageBox.Show("Your Data has been Successfully saved.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                }
        }
         

private void btnRead_Click(object sender, EventArgs e)
        {
            using (OpenFileDialog ofd = new OpenFileDialog() { Filter = "CSV|*.csv", ValidateNames = true })
            {
                if (ofd.ShowDialog() == DialogResult.OK)
                {
                    
                        var sr = new StreamReader(new FileStream(ofd.FileName, FileMode.Open));
                        var csv = new CsvReader(sr);
                          lunchBindingSource.DataSource = csv.GetRecords<Lunch>().ToString();
                        lunchBindingSource.DataSource = csv.GetRecords<Lunch>(); /// use to create file
                    }
               }
            }

Posted 10-Feb-17 13:27pm

Member 12349103

Updated 14-Mar-17 0:54am

v3

Add a Solution

Comments

[no name] 10-Feb-17 20:23pm

The very first thing for you to do is to stop ignoring exceptions.
The second thing for you to do is to learn how to debug your code. And, really do it this time.

[no name] 11-Feb-17 10:19am

https://www.codeproject.com/Questions/1169546/Null-reference-when-writing-to-csv-file

Again, what is your question? Reposting the same thing over and over isn't going to help you. Ignoring exceptions aren't going to help you either. You need to find out what the error means and fix it. You already know where it occurs and why now you need to fix it.

[no name] 11-Feb-17 20:10pm

You learn how to use the debugger, find the object that is null and fix your error.

Karthik_Mahalingam 10-Feb-17 22:16pm

Always use Reply button to post comments/query to the concerned user, so that the user gets notified and respond to your text.

3 solutions

Solution 1

Start by (as NotPoliticallyCorrect says) not ignoring exceptions.
When you write code like this:

C#

try
{
	... code ...
}
catch (Exception ex)
{
}

You are deliberately throwing away any information that might be available on what is causing a problem. It's a bit like getting a puncture in the car and just turning the music up to drown out the noise - it will come back to bite you later, and a lot harder than if you had stopped and looked at the problem!
So add code to your catch block to report the problem - a MessageBox for example (if this is a WinForms or WPF app).
And then put a breakpoint on the using line in your Read button click handler and step through the code in the debugger to see exactly what is happening and when.

You need information - and we can't get it for you, as we don't have access to your data!

Posted 10-Feb-17 21:21pm

OriginalGriff

Solution 2

As you have been told, remove the try/catch from your code.
The try/catch is here to hide failures in your code, and the reason and the position of failure.
Advice: never use try/catch until you know exactly why you do it. And use it until you finished debugging your code.

When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. It allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.

Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to.

Posted 10-Feb-17 23:06pm

Patrice T

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)

Member 12349103 · Accepted Answer · 2017-03-14T00:54:00

I added this piece of code and fixed the issue.

C#

lunchBindingSource.ResetBindings(false);
                 
                        var lunchList = lunchBindingSource.List as IList<Lunch>;
                        foreach (Lunch s in lunchList)
                        {
                            writer.WriteRecord(s);
                        }