I am working on VB in Visual Studio 2010. And I've seen errors of greatness in which when I double click on a line of datagridview, I get the values of its columns in such a way.
Datagridview1.SelectedRows(0).Cells(1).Value
But the most surprising thing is that with this same code I get the values of different columns each time without changing the index value in Cells(). I also put the name of the column inside the Cells(), but I did not get any value from this too.
Datagridview1.SelectedRows(0).Cells("name").Value
And the first column of this datagridview Cells(0) always returns the null value itself. I do not know how.
I have also used some column formating. like
With Datagridview1
.ColumnCount =2
.Columns(0).HeaderText ="Name"
.Columns(0).DataPropertyName = "pname"
.Columns(0).Width =100
.Column(1).HeaderText = "Son of"
.Column(1). DataPropertyName = "fname"
The big problem here is that it gives value to different columns each time with a single code
Is there any solution available for this?
Related
I have a combo box in Access named StateID. It's rowsource contains two columns one is ID which is in Column 0 and another is description which is Column 1.
I want to populate the value of the ID column by doing something like:
StateID.Column(0) = rs("ID")
I made sure that the combobox is name StateID. The rs("ID") is also returning a value but my code breaks on the line above and I get
Object Required
error.
I alos tried Me.StateID.Column(0) and StateID.Column(0).value but I still get the same error
You cannot do "something like" that because the "Column" property is Read-Only, per Microsoft Access documentation; seems like this is your problem.
I dont' know why you don't assign the record source in design mode. Any way, in the Form Load event you can do this
StateID.RowSource = "SELECT codage,nomage FROM TheTable"
Well I just tried various things and doing it this way works:
With StateID
.ColumnCount = 2
.Value = rs("ID")
End With
I'm using VB.NET to make a stand-alone executable containing an unbounded DataGridView.
One of its columns is a combobox. I add rows to the combobox with some simple code
like this:
For r As Int16 = 0 To eachLine.GetUpperBound(0)
Dim dgvcbc As DataGridViewComboBoxColumn = grd.Columns(col)
' Errors: dgvcbc.Items.Clear()
dgvcbc.Items.Add(eachLine(r))
Next r
Works great the first time, but when I try to clear it, in order to add some different
items in the combobox, I get this error 100s of times:
> DataGridViewComboBoxCell value is not valid
Any ideas on how to fix this and why it occurs?
The issue is that, if you clear the Items in that column, every cell in that column becomes invalid. Every value in that column has to match one of the items in the drop-down list and, if there's no items, no value can be valid. It doesn't make sense to clear the drop-down list. You must leave at least the items that match the values in the cells of that column.
I am having some trouble with a sorting an unbound DataGridView. I am filling a DataTable from a StreamReader, and then manually transferring the items from the DataTable to the DataGridView. The AllowUserToAddRows property is set to true on the DataGridView.
This populates the DataGridView, without any trouble. I can sort the columns by clicking on the column headers without any issue. If I add a value to the first column in a new row, and then try to sort the column, I get an error message that shows: "Object must be of type String."
I have tried different ways of converting all of the cells in the column to the same datatype, but I cannot get around this issue. Am I missing something here?
In the form load event, I have the following code:
dgvStartingGrid.Columns(0).ValueType = GetType(Integer)
I also am making sure that the values from the StreamReader are Integer types before entering them in the DataGridView:
If IsNumeric(strColumnValue) Then
dtbFillGrid.Rows(intCurrentRow).Item("Starting Position") = strColumnValue
End If
I have also tried:
dtbFillGrid.Rows(intCurrentRow).Item("Starting Position") = CInt(strColumnValue)
What could cause this issue? I have verified that all of the cells in the column are of the same datatype, but it still gives me an error, and I am sure that it is this column that is the problem.
The other columns are of string type, and I do not have any issue sorting them by their column headers, unless I click the first column, and then the exception is thrown.
Right, after some testing I found this out.
Even though you have set your DataGridView column to be Integer it doesn't mean that it will be filled with Integers. Unless you alter the datatype of the DataTable the DataGridView is actually filled with strings. The sorting function on a DataGridView is not based on column type, it is based on the first value it finds. And since you that value is a string, you get an error when it reaches your typed value (which is an Integer).
So here is what you have to do.
dtbFillGrid.Columns.Item(0).DataType = GetType(Integer)
Where 0 is the column containing Integer.
I have an access database, with a form, that contains numerous textboxes. The textboxes are filled with currency data based on a selection made by the user. Each record may have different values some may have no values. I need to add 3 of the txtboxes together but the value always shows as Null.
me.txt1 = Nz(me.txt2.value + me.txt3.value + me.txt3.value)
txt2 = 23.04
txt3 = Null(empty)
txt4 = 15.64
The value of txt1 should be 38.68 instead its coming out Null. The textboxes are populated by a subroutine that is called from the AfterUpdate event of a dropdown.
Where do you use that formula ? Is it in VBA ? You don't need it.
If it's from the Control Source of txt1, then Meshould be replaced by Form (or by nothing at all)
In the Control Source property of txt1, type = nz(txt2)+nz(txt3)+nz(txt4)
That should be all you need. No VBA.
Another solution, IF the source of the form is a Query, is to add a calculated field in the query.
In both cases, of course you will NOT store that data (which would violate 3rd Normal form)
I have a datagridview that has been populated from a datatable using the datasource property. I need to change the value of a cell without affecting the database. So far I could only find that I have to first change the databound item but no information about how to do that. Besides, I don't want to change the databound item.
The reason for wanting to do this is that I have a list of records with a start and end time and there is a computed field that gives the difference in seconds. I need to change the value of the computed field and change the height of the row accordingly, that is, the height of each row is proportional to the duration it represents. Changes are done from a text box which increments quickly if the "increase" button is kept down and therefore I cannot change the database with each increment. Rather I would change the value in the table frequently and update the database once the increments stops.
I have tried updating the datagridview directly using this code:
dgvTasks.Rows(SelectedRowIndex).Cells(5).Value = DateAdd(DateInterval.Minute, DateDiff(DateInterval.Minute, CDate("00:00:00"), CDate(txtDuration.Text & ":00")), dgvTasks.Rows(SelectedRowIndex).Cells(4).Value)
But receive the error:
System.Data.ReadOnlyException: Column 'Column1' is read only.
I also tried updating the datatable, and allowing the calculated column to update:
dtblTasks.Rows(SelectedRowIndex)(5) = DateAdd(DateInterval.Minute, DateDiff(DateInterval.Minute, CDate("00:00:00"), CDate(txtDuration.Text & ":00")), dtblTasks.Rows(SelectedRowIndex)(4))
dgvTasks.DataSource = dtblTasks
But the calculated value doesn't change.
I am also providing an additional calculated value (in the SQL) where I find the difference in minutes and the append a string literal to that:
( CAST ( DATEDIFF(MINUTE, Tasks.TaskStart, Tasks.TaskEnd) AS NVARCHAR(10) ) + ' mins') AS TaskDurationString
Is there a way to detach the grid from the datasource but still keep the data visible in the datagrid and manipulate it (without affecting the databound object)? Or perhaps some other approach to this problem?
Updating the calculated column in the DataTable should work - I've just tried it, and both when I edit one of the values that are part of the calculated value, and when I change the value in code, that column is recalculated and the grid UI updates.
One thing to check is that you are calculating the value correctly. You should be using the DataTable~ column [Expression` property]1. Something like this:
dt.Columns["FullName"].Expression = "FirstName + LastName";
Since it appears that you don't actually need to bind any of these values to the DataTable or persist them to the database, one possible solution is to do all of this in an unbound DataGridView calculation column.
To do that add a column using the designer, then in the cell validating event have something like this:
void dataGridView1_CellValidated(object sender, DataGridViewCellEventArgs e)
{
dataGridView1.Rows[e.RowIndex].Cells["TargetColumn"].Value = dataGridView1.Rows[e.RowIndex].Cells["FirstName"].Value.ToString() + dataGridView1.Rows[e.RowIndex].Cells["LastName"].Value.ToString();
dataGridView1.Rows[e.RowIndex].Height = dataGridView1.Rows[e.RowIndex].Cells["LastName"].Value.ToString().Length + dataGridView1.Rows[e.RowIndex].Cells["FullName"].Value.ToString().Length;
}