Develop Reference

WPF drop-down list for auto generated column in datagrid

How to make a drop-down list when you click on an element of a specific table column in which you can select an element for this cell? Column is auto generated.

A Combobox in xaml/wpf is used like this:
<ComboBox x:Name="some Name" SelectionChanged="comboboxChanged">
<ComboBoxItem>The Content of your Combobox</ComboBoxItem>
</Combobox>
ComboBoxItems are essentially the dropdown part. You can add as many as you want.
In your back end (c#) you can get the selected Value as soon as the "SelectionChanged"-event is triggered. The code for getting the selected Value can be done multiple ways. Example:
private void comboboxChanged(object sender, SelectionChangedEventArgs e){
string comboboxvalue = comboboxname.Text;
//Then set associated textblock or label
labelname.Content = comboboxvalue;
}
The code above would be static though. Dynamically generating these elements could look like this for instance.
When auto-generating, using an inline function for the event is easy.
for (int i = 0; i < 10; i++){
ComboBox comboboxname = new ComboBox();
comboboxname.SelectionChanged += (ss,ee) { string comboBoxValue = comboboxname.Text; labelname.Content = comboBoxValue;}
}
Labelname being the name of the Label you want to set. In that loop you will need to implement a way of giving each box a unique name and getting the name of the associated label in there as well. That you will have to figure out on your own as i do not know how and what exactly is generated and what is static.
You will also need to add your dynamically created combobox to your listpanel or grid or whatever you are using. This works like this:
listpanelname.Children.Add(comboboxname);
Just add that to the "for" loop.

Repository item lookUpEdit resets after losing focus

I have this problem for days and can't find solution for it. I tried all possible solutions i found on internet, but seems like none suits this one.
Thing is that i added repository item to gridControls (i added it through designer, not through code). Then, in code i added data source to that repository lookUpEdit and i have items in dropDown in that column. But when i select item in repository and click on other cell, Selected item in repository is cleared and repository shows null value again...
Any ideas what i did wrong ?
EDIT:
Also, when i click on any cell in my grid, i have delay of second or two, and after that delay clicked cell is focused... Any solutions for all of this?
EDIT:
Don't know what code to show You, because I did all in devExpress designer. Here is part of the code where I set data source to repository item, and i will give You code from designer of that repository item.
private void ConfigureRepositoryItems()
{
BetService.SportManagerClient dbSportManager = new BetService.SportManagerClient();
BetService.BLOddsControlSettings[] oddsControlSettings = dbSportManager.GetOddsControlSettings("", "");
repositoryOddsControlSettings1.DataSource = oddsControlSettings;
}
And here is code from designer:
//
// repositoryOddsCalculationSettings1
//
this.repositoryOddsCalculationSettings1.AutoHeight = false;
this.repositoryOddsCalculationSettings1.Buttons.AddRange(new DevExpress.XtraEditors.Controls.EditorButton[] {
new DevExpress.XtraEditors.Controls.EditorButton(DevExpress.XtraEditors.Controls.ButtonPredefines.Combo)});
this.repositoryOddsCalculationSettings1.Columns.AddRange(new DevExpress.XtraEditors.Controls.LookUpColumnInfo[] {
new DevExpress.XtraEditors.Controls.LookUpColumnInfo("ID", "ID", 20, DevExpress.Utils.FormatType.None, "", false, DevExpress.Utils.HorzAlignment.Default),
new DevExpress.XtraEditors.Controls.LookUpColumnInfo("Name", "Name")});
this.repositoryOddsCalculationSettings1.DisplayMember = "Name";
this.repositoryOddsCalculationSettings1.Name = "repositoryOddsCalculationSettings1";
this.repositoryOddsCalculationSettings1.NullText = "Select Settings";
this.repositoryOddsCalculationSettings1.PopupSizeable = false;
this.repositoryOddsCalculationSettings1.ValueMember = "ID";

For starters check whether the column name in your Grid datasource and the column in your grid control match. The match is case sensitive so name and Name are not same and hence can cause this issue. Secondly make sure the Grid datasource column datatype matches the value type of the LookUpEdit. If the LookupEdit is returning int and the Grid datasource column datatype is string, this alone can cause lots of headaches.

How to set max length of datagridview column

I have a DataGridView where the units can be entered in a TextBox column.
How do I restrict the input length of this column to 6 characters?

Use the MaxInputLength property of the DataGridViewTextBoxColumn.
This property is available through the Designer or through code:
((DataGridViewTextBoxColumn)dataGridView1.Columns[yourColumn]).MaxInputLength = 6;

Please use CellValueChanged event of DataGridView.
In the handler of the event you can check ColumnIndex and RowIndex properties of DataGridViewCellEventArgs argument to identify that grid's field of interest is edited and then - take appropriate actions.
As stated in other answers - most natural way to restrict text lengths for DataGridView field is to modify respective grid column properties. Properties of grid columns can be altered on Edit Columns form that is invoked for grid control in form designer with right click menu item Edit Columns...:

You may have to play with cell-edit events.
http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridview.cellvaluechanged.aspx

You don't necessarily have the columns ready to manipulate if you're using data binding. For data binding, using the ColumnAdded listener can help:
public FormSingleValidation(BindingList<ValidateSingle> validateSingles)
{
InitializeComponent();
dataGridViewSingleValidation.ColumnAdded += ColumnAdded;
this.validateSingles = validateSingles;
var source = new BindingSource(validateSingles, null);
dataGridViewSingleValidation.DataSource = source;
}
private void ColumnAdded(object sender, DataGridViewColumnEventArgs e)
{
if(e.Column.GetType() == typeof(DataGridViewTextBoxColumn))
{
DataGridViewTextBoxColumn column = (DataGridViewTextBoxColumn) e.Column;
column.MaxInputLength = 6;
}
}
Caveats
Obviously this applies to all text columns without discrimination, you can add a conditional filter using the column's name if you only want specific columns to be effected.

How to change cell value dynamically in ListView with GridView

I have used the GridView inside the ListView. I want to dynamically change a cell value. For example, there is a column named "Time", I wanna to change this value when something happens. I can find and get the cell (e.g od.Time as in following codes), but can not change its value. Some codes like this where ObjectData is the class for all ListView columns.
for (int i = 0; i < 5; i++)
{
ObjectData od = (ObjectData)objectListView.Items[i];
if (od.UserName == "Tom")
{
od.Time = DateTime.Now.ToString();
}
}

If the your listview is bound to a data source you'll need to change the data source's data, not the listview's contents. It should then update the listview.

Set SelectedValue in DataGridViewComboBoxColumn or DataGridViewComboBoxCell

I would like to set a value to the ComboBox in the DataGridView. I already have changed the comboBoxItems, I just want to select one of them. Thank you in advance!!!

I already solved my problem... I'm gonna post the way I did and hoppefully someone will find this answer too.
dgrDetalle.DataSource = dataTable("select * from yourTable");
DataTable dtCombo = dataTableCombo("select COL_ID DETOC_COL_FK,COL_DESCRIPCION from yourTable2");
string[] strColumns = new string[] { "COL_DESCRIPCION" };
MultiColumnDictionary map = new MultiColumnDictionary(dtCombo, "DETOC_COL_FK", strColumns, 0);
dgrDetalle.Cols["DETOC_COL_FK"].DataMap = map;
As you can see the class that save my life is MultiColumnDictionary.
Note: The combobox items must be loaded in a different DatatTable than the DataTable that is gonna load directly in the grid.

As far as I know, the Comboboxes only actually exist as controls when they are being edited, and therefore don't have a selected item property.
You can simply set the Value property of the cell to the item you want selected, or alternitively, you can set a default value by setting the property:
DataGridViewColumn.DefaultCellStyle.NullValue.