C# – Compare old and new value in DataGridView cell

cdatagridviewnet

How to change DataGridView cell ForeColor based on whether new cell value is > or < than current/old cell value? Is there an event which passes the new value before the current is changed, so I can compare them?

The data is updated from underlying source, and may be bound by BindingSource.

Best Answer

I ran into a similar issue. I tackled this by using the CellValidating event instead:

void dgv_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
{
    var oldValue = dgv[e.ColumnIndex, e.RowIndex].Value;
    var newValue = e.FormattedValue;
}

Admittedly, I just needed access to the old value, I didn't need to perform any formatting. I'm sure you can apply formatting through this event handler, though.

Related Solutions

C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}

C# – How to programmatically set cell value in DataGridView

If the DataGridView is databound, you shouldn't directly modify the content of the cell. Instead, you should modify the databound object. You can access that object through the DataBoundItem of the DataGridViewRow :

MyObject obj = (MyObject)dataGridView.CurrentRow.DataBoundItem;
obj.MyProperty = newValue;

Note that the bound object should implement INotifyPropertyChanged so that the change is reflected in the DataGridView

Best Answer

Related Solutions

C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

C# – How to programmatically set cell value in DataGridView

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