I have a form with two data-bound text boxes, one data-bound DateTimePicker and a BindingNavigator. I bind these components at run-time to the relevant data sources (the 'Text' and 'Value' of the Text Boxes and DateTimePicker respectfully are bound the relevant fields in a data set). All the components display the present records correctly. Normally, when one clicks the "Add New Item" button on the navigator, all the Text Boxes will clear in preparation for the new entry. However, I have the problem that this does not occur when the DateTimePicker is bound, and furthermore any attempts to update the datasets do not occur correctly. If I neglect to bind the DateTimePicker then all works as expected. What is the cause of this behaviour and is there a way around it?
The DateTimePicker doesn't support binding to nullable data. When you add a new row, the value for that field will be DBNull.Value by default and that cannot be converted successfully to a value that can be assigned to the Value property of the DateTimePicker, which is type DateTime. You need to either extend the DateTimePicker and add a new property that supports both DateTime values and DBNull objects and bind that or else set the DefaultValue property of your DataColumn so that there will always be a DateTime to display in the DateTimePicker.
This problem was resolved for my scenario by simply controlling the addrow method of the binding source based on this site: http://www.vbforums.com/showthread.php?645401-RESOLVED-datetimepicker-with-binding-source
Add a new button on the binding navigator (to use as your 'Add') and remove the old one.
Connect to the click event and set the datetime of the new row being added:
DataRowView row = (DataRowView)bs_.AddNew();
row["dbDateTime"] = DateTime.Now;
where dbDateTime is your database field.
Although you may have to add some more code to the click event, such as moving to the newly added row on the datagrid, this option was by far the easiest to implement.
Related
I have plumbed the deeps of my google-fu to find an answer.
First, I am not simply asking how to bind a combobox to a datasource. It's a bit more than that unless I'm having a serious understanding gap.
On my Winform, I have a DataGridview on the left and on the right I have a panel with values from the selected row on the left. One of those controls on the right is the ComboBox I'm having trouble with. I have my bindingsource and dataview set up and the other controls on the right are working splendidly, except the ComboBox control.
The user, interacting with this ComboBox, should see values such as "Item ABC" and "Item EFG" and the value related to them might be 1234 and 5678. If this was a fully unbound control I'd put an object array of items in. Once I get it working, I'd load that from a different source.
But when I try to DataBindings.Add("??", dataview, "dataviewfield", ...) I can't get the proper value for "??". Runtime debug shows that "SelectedItem.Value" would be the right option, but I get "not found" type exception when I use that. I've tried "SelectedValue" as well, but that didn't work (debug show's it's null & throws no nulls allowed exception).
How can I get that value placed directly into the DataView via the Binding?
Setting the .DataSource simply loses the items and doesn't help at all.
How does one do this? Short of making the ComboBox unbound totally, setting the selectedindex directly and capturing the value when the selected index changes changes - Just seems so clunky to have to do that.
-old programmer
Further Notes: I edited to clarify the placement of the ComboBox.
I have made progress (naturally, only after asking a question does a new avenue pop into my head). I got to thinking I might need a custom binding adapter so started googling that. I found some samples doing what I want.
The foremost problem was I was not using assigning a datasource on the ComboBox, I was simply adding items. When I created a two column dataset and a few rows (could have been anything I suppose) and set that and the two field names as the ComboBox's displaymember and valuemember did the SelectedValue start showing a value (instead of null all the time).
I think that was the problem. The remaining issue is getting the left hand side to re-display/refresh after the change.
When loading the datasource for the DataGridView and the bindingsource, try making them share the same list:
BindingSource1.Datasource = dataset
DataGridView.Datasource = BindingSource1
This should mean that any changes to the data in the bindingsource will also update the DataGridView.
To edit the selected object then just handle the SelectionChanged event and set the BindingSource1.Position to the index of the selected object in the Datasource.
I'm working on a GUI that allows the user to manipulate xml files. I display the xml file in a datagridview organized neatly by columns through xml elements. I allow the user to add columns as an extention on my project. The column gets added to the dataset table, then updated to the datagridveiew that I use to display the xml file in. I've included the ability for the user to add a combobox column to select choices instead of entering them in constantly like.. true or false. However, that is where the problem lies. Saving a normal column was easy. The combobox column is being a pain.
I have a "save combobox column" to have it updated to the xml and a "save" button to save in a destination of the user's choice.
I've done some research and it seems like the combobox class has such a feature to gain access to the selecteditem in the combobox put in by the user.
Where we have:
ComboBox box = new ComboBox();
box.SelectedItem;
I tried applying this to the combobox column class but it does not have such a function. Thus, I cannot figure out how to directly obtain the value of the user's selected item. I tried experimenting with comboboxcell's as well, but that didn't lead me anywhere either. Both those classes I played around with do not have a... "selected item" function and even google does not have a solution for me. =( I've also tried using the cell.value, but it is "null" for some reason. Even when the user selects an item in the box, it doesn't get saved into the cell's value.
TLDR:
My question in short is, how, if possible, do you gain access to the comboboxcolumn cell's selected item? Additionally, how would you then ensure that the item value is saved in the cell?
Thanks in advance. I'm using .NET 3.5 SP1, through Visual Studio 2008 C#.
Sincerely,
tf.rz
The Control in a DataGridView is not a ComboBox, it is a DataGridViewComboBox and has different properties and methods. From MSDN
Unlike the ComboBox control, the DataGridViewComboBoxCell does not have SelectedIndex and SelectedValue properties. Instead, selecting a value from a drop-down list sets the cell Value property.
However, you mentioned that the Cell.Value is null for you. Well there may be another step you are missing according to the following article (How to: Access Objects in a Windows Forms DataGridViewComboBoxCell Drop-Down List).
You must set the DataGridViewComboBoxColumn.ValueMember or DataGridViewComboBoxCell.ValueMember property to the name of a property on your business object. When the user makes a selection, the indicated property of the business object sets the cell Value property.
If we have bound a datagridcomboboxcell with a different DisplayMember and ValueMember, like so:
dgcombocell.DisplayMember = "Name";
dgcombocell.ValueMember = "Id";
dgcombocell.DataSource = dataset1.Tables[0];
Then for getting SelectedText, and SelectedValue, we can write this code:
string SelectedText = Convert.ToString((DataGridView1.Rows[0].Cells["dgcombocell"] as DataGridViewComboBoxCell).FormattedValue.ToString());
int SelectedVal = Convert.ToInt32(DataGridView1.Rows[0].Cells["dgcombocell"].Value);
I hope it solves your problem.
Use this to get or set selected value:
object selectedValue = currentRow.Cells["comboboxColumnName"].Value
Don't forget to set DisplayMember and ValueMember for your DataGridViewComboBoxColumn
This is how it is done
DataGridViewComboBoxCell comboCell = (DataGridViewComboBoxCell)dgv.Rows[0].Cells[1];
MessageBox.Show(""+comboCell.Items.IndexOf(comboCell.Value));
A .Net combox is actually a composite control made up of a textbox and a dropdownlist. Use box.Text to get the currently displayed information.
EDIT: The row or the cell should have a .FindControl() method. You'll need to do something like:
Combobox box = (Combobox)(row.FindControl("[combobox ID]"));
string val = box.Text;
Basically, you're finding the control within its container (row or cell), then casting the control found as a combobox, then accessing its .Text property.
I use this:
private int GetDataGridViewComboBoxCellSelectedIndex(DataGridViewCell d)
{
return ((DataGridViewComboBoxCell)d).Items.IndexOf(d.Value);
}
I have a DataGridView in a C# WinForms app that is DataBound at runtime (through Form_Load) to a custom Object.
In the design view of the DataGridView I have no columns set up.
When the Form loads the the columns are automatically created based on the data in the Custom object that it is DataBound to.
My question is how can I control the the Columns that are automatically created.
For example if I want one of the columns to be a DataGridViewLinkColumn instead of the DataGridViewTextBoxColumn that is automatically created?
The default columns are based on the data-type. I haven't checked, but for a link you could try exposing the data as Uri, but that might be hopeful. Really, if you want a specific type of column - add the columns through code and set DataGridView.AutoGenerateColumns to false.
As Andrew implies; normally something like reflection is used to generate the columns, and you'll get a column for every (browsable + public + readable) property. There is a layer of abstraction on top of this if you need, but this won't help with adding a hyperlink column.
You can pre-create your columns in the designer. If the name of the column matches the name of the property the column will end up bound to, the databinding will take care of the DGV population for you as before.
Edit 1
I believe my problem stems from the following. The function that fills the dropdown portion sets the Display Member to the CountyName. Then when I try and set the SelectedText or EditValue, as has been suggested, that function only returns the CountyID which it try's to match to something in the DropDown list DisplayMember. I need it to match it to something in the ValueMember list.
Using the following I got it to work but it is a HACK and I'd greatly appreciate finding a real solution.
lkuResidenceCounty.ItemIndex = Convert.ToInt32(row["ResidencyCountyID"].ToString());
Original Post
I have a lookup box(DevExpress) on a member form that I fill the possible values in from the DB with this code -->
lkuResidenceCounty.Properties.DataSource = ConnectBLL.BLL.Person.CountyList();
lkuResidenceCounty.Properties.PopulateColumns();
lkuResidenceCounty.Properties.DisplayMember = "CountyName";
lkuResidenceCounty.Properties.ValueMember = "CountyID";
lkuResidenceCounty.Properties.Columns[0].Visible = false;
lkuResidenceCounty.Properties.Columns[2].Visible = false;
lkuResidenceCounty.Properties.Columns[3].Visible = false;
This works just fine as the CountyName is displayed as expected.
However, When I try and load an existing member's value for this field using the below, which is part of a function that takes a row from the DataSet -->
lkuResidenceCounty.Properties.ValueMember = row["ResidencyCountyID"].ToString();
I get a blank box. I have stepped through the code and the correct ID is being returned for the member.
Unfortunately the stored procedure to fill the dropdown options pulls from a Maintenance Table with the columns "CountyName" & "CountyID". So that is correct. Unfortunately, the stored procedure to load a specific person's current county pulls from the Person Table where there is a column called "ResidencyCountyID". It is so named because there is also a "ResponsibilityCountyID" column.
I need a way for them both to coexist, any solutions?
Thanks!
DisplayMember and ValueMember are used to populate the control with the list of selectable values. To set the selected value of a populated LookUpEdit control, set its EditValue property:
lkuResidenceCounty.EditValue = row["ResidencyCountyID"].ToString();
In response to your edit: According to the documentation:
The currently selected row determines values for the editor's edit value and display text. The value for BaseEdit.EditValue is obtained from the RepositoryItemLookUpEditBase.ValueMember field, while the text to display in the edit box is obtained from the RepositoryItemLookUpEditBase.DisplayMember field of the selected row.
When you change BaseEdit.EditValue,
the editor locates and selects the row
whose
RepositoryItemLookUpEditBase.ValueMember
field contains the new value. The text
in the edit box is changed to reflect
the newly selected row.
I don't use these controls but it sounds to me that it shouldn't be working as you described. I think the ToString() is the problem because EditValue accepts an object so it's probably expecting an int for the value. Try:
lkuResidenceCounty.EditValue = (int)row["ResidencyCountyID"];
The ValueMember property tells the list what field to pull from when setting the Value property. Once you've set the ValueMember to "CountyID", then when the list is Databound, it will set all the list items' value properties to their respect objects' CountyID fields.
Hence, you should not do:
lkuResidenceCounty.Properties.ValueMember = row["ResidencyCountyID"].ToString();
but rather
lkuResidenceCounty.Properties.ValueMember = "CountyID";
was perfectly fine, as long as you've correctly identified the field you're trying to databind. Once the list get's databound you should see the results you're expecting.
However, after looking at your code, it seems that you're mismatching your field. In one place you're using ResidencyCountyID and in another you're using CountyID. That is most likely your source of confusion. Figure out what the actual field name is and make sure you set the ValueMember to that.
UPDATE
After reading your comment, what your looking for is the SelectedValue property. The SelectedValue property tells the list to force the selected value to whatever input you give it.
Essentially you have two things going on here. ValueMember tells the list what to use as the value from your data source, and SelectedValue which tells the list what the currently selected value should be.
Why is it that you need the same LookUpEdit to have two value members? Is it being used standalone or in a grid? If standalone, you could swap out the two repository editors depending on the current row. But, are there more than 2 possible values for the ValueMember? That would also complicate things.
UPDATE
Looking at your edit, I think I understand what's going on a little more. So, you don't wish to change your ValueMember (which refers to a data column), but rather to change the value of the editor? If so, then you should definitely use EditValue (not SelectedText, which I don't believe is meant to be set), and assign it to row["value_field"] like so:
lkuResidenceCounty.EditValue = row["ResidencyCountyID"];
What happens when you do that?
ASP.NET 1.1 - I have a DataGrid on an ASPX page that is databound and displays a value within a textbox. The user is able to change this value, then click on a button where the code behind basically iterates through each DataGridItem in the grid, does a FindControl for the ID of the textbox then assigns the .Text value to a variable which is then used to update the database. The DataGrid is rebound with the new values.
The issue I'm having is that when assigning the .Text value to the variable, the value being retrieved is the original databound value and not the newly entered user value. Any ideas as to what may be causing this behaviour?
Code sample:
foreach(DataGridItem dgi in exGrid.Items)
{
TextBox Text1 = (TextBox)dgi.FindControl("TextID");
string exValue = Text1.Text; //This is retrieving the original bound value not the newly entered value
// do stuff with the new value
}
So the code sample is from your button click event?
Are you sure you are not rebinding your datasource on postback?
When are you attempting to retrieve the value from the TextBox? i.e. when is the code sample you provided being executed?
If you aren't already, you'll want to set up a handler method for the ItemCommand event of the DataGrid. You should be looking for the new TextBox value within that method. You should also make sure your DataGrid is not being re-databound on postback.
I would also highly recommend reading through Scott Mitchell's excellent article series on using the DataGrid control and all of it's functions:
https://web.archive.org/web/20210608183626/https://aspnet.4guysfromrolla.com/articles/040502-1.aspx