. Abstract The first two releases of the.NET Framework (.NET 1.0 and.NET 1.1) left a glaring gap in the data-binding picture. Although developers had a flexible, configurable model for linking almost any control to almost any data source, they didn’t have a practical way to display full tables of information.
Hierarchical Datagridviewcomboboxcellulitis
The only tool included for this purpose was the DataGrid control, which worked well for simple demonstrations but was woefully inadequate for real-world code. Most developers found that the DataGrid was awkward to use, inflexible, and almost impossible to customize. Oddly enough, the DataGrid lagged far behind its ASP.NET counterpart, making it more difficult to display rich data-bound tables in a Windows application than in a web page.
I have a combo box on a WinForms app in which an item may be selected, but it is not mandatory. I therefore need an 'Empty' first item to indicate that no value has been set. The combo box is bound to a DataTable being returned from a stored procedure (I offer no apologies for Hungarian notation on my UI controls:p ): DataTable hierarchies = database.GetAvailableHierarchies(cmbDataDefinition.SelectedValue.ToString).Copy;//Calls SP cmbHierarchies.DataSource = hierarchies; cmbHierarchies.ValueMember = 'guid'; cmbHierarchies.DisplayMember = 'ObjectLogicalName'; How can I insert such an empty item? I do have access to change the SP, but I would really prefer not to 'pollute' it with UI logic. Update: It was the DataTable.NewRow that I had blanked on, thanks. I have upmodded you all (all 3 answers so far anyway).
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I am trying to get the Iterator pattern working before I decide on an 'answer' Update: I think this edit puts me in Community Wiki land, I have decided not to specify a single answer, as they all have merit in context of their domains. Thanks for your collective input. There are two things you can do:. Add an empty row to the DataTable that is returned from the stored procedure. DataRow emptyRow = hierarchies.NewRow; emptyRow'guid' = '; emptyRow'ObjectLogicalName' = '; hierarchies.Rows.Add(emptyRow); Create a DataView and sort it using ObjectLogicalName column. This will make the newly added row the first row in DataView. DataView newView = new DataView(hierarchies, // source table ', // filter 'ObjectLogicalName', // sort by column DataViewRowState.CurrentRows); // rows with state to display Then set the dataview as DataSource of the ComboBox.
If you really don't want to add a new row as mentioned above. You can allow the user to set the ComboBox value to null by simply handling the 'Delete' keypress event. When a user presses Delete key, set the SelectedIndex to -1.
You should also set ComboBox.DropDownStyle to DropDownList. As this will prevent user to edit the values in the ComboBox.
Datagridview Combobox Column
The DataGridViewComboBoxCell class is a specialized type of used to display a combo box control, which is an editing field combined with a list selection field. The currently selected DataGridViewComboBoxCell hosts a in which the user can edit the cell's value, assuming the cell's property is set to false. The is the column type specialized to hold cells of this type. To model the cells within a column after an existing DataGridViewComboBoxCell, set the column's property to that cell. By default, the CellTemplate is initialized to a new DataGridViewComboBoxCell.
The cell-related properties of the column are wrappers for the similarly-named properties of the template cell. Changing the property values of the template cell will affect only cells based on the template that are added after the change. Changing the cell-related property values of the column, however, will update the template cell and all other cells in the column, and refresh the column display if necessary. Notes to Inheritors When you derive from DataGridViewComboBoxCell and add new properties to the derived class, be sure to override the method to copy the new properties during cloning operations. You should also call the base class's Clone method so that the properties of the base class are copied to the new cell.
Add Combobox To Datagridview
The DataGridViewComboBoxCell class is a specialized type of used to display a combo box control, which is an editing field combined with a list selection field. The currently selected DataGridViewComboBoxCell hosts a in which the user can change the cell's value, assuming the cell's property is set to false. Unlike the control, the DataGridViewComboBoxCell does not have and properties. Instead, selecting a value from a drop-down list sets the cell property. The is the column type specialized to hold cells of this type. By default, the is initialized to a new DataGridViewComboBoxCell.
To pattern the cells within a column after an existing DataGridViewComboBoxCell, set the column's property to the cell to use as a pattern. The cell-related properties of the column are wrappers for the similarly-named properties of the template cell. Changing the property values of the template cell will affect only cells based on the template that are added after the change. Changing the cell-related property values of the column, however, will update the template cell and all other cells in the column, and refresh the column display if necessary. You will typically work with the type unless you want to override column values for specific cells.
The guidelines described in the class overview topic for populating the drop-down list applies to both cell and column instances.