DataControlField.ExtractValuesFromCell(IOrderedDictionary, DataControlFieldCell, DataControlRowState, Boolean) Metodo
Definizione
Estrae il valore del campo di controllo dati dalla cella corrente della tabella e aggiunge il valore all'insieme IDictionary specificato.Extracts the value of the data control field from the current table cell and adds the value to the specified IDictionary collection.
public:
virtual void ExtractValuesFromCell(System::Collections::Specialized::IOrderedDictionary ^ dictionary, System::Web::UI::WebControls::DataControlFieldCell ^ cell, System::Web::UI::WebControls::DataControlRowState rowState, bool includeReadOnly);
public virtual void ExtractValuesFromCell (System.Collections.Specialized.IOrderedDictionary dictionary, System.Web.UI.WebControls.DataControlFieldCell cell, System.Web.UI.WebControls.DataControlRowState rowState, bool includeReadOnly);
abstract member ExtractValuesFromCell : System.Collections.Specialized.IOrderedDictionary * System.Web.UI.WebControls.DataControlFieldCell * System.Web.UI.WebControls.DataControlRowState * bool -> unit
override this.ExtractValuesFromCell : System.Collections.Specialized.IOrderedDictionary * System.Web.UI.WebControls.DataControlFieldCell * System.Web.UI.WebControls.DataControlRowState * bool -> unit
Public Overridable Sub ExtractValuesFromCell (dictionary As IOrderedDictionary, cell As DataControlFieldCell, rowState As DataControlRowState, includeReadOnly As Boolean)
Parametri
- dictionary
- IOrderedDictionary
Oggetto IOrderedDictionary.An IOrderedDictionary.
- cell
- DataControlFieldCell
Oggetto DataControlFieldCell contenente il testo o i controlli dell'oggettoDataControlField.A DataControlFieldCell that contains the text or controls of the DataControlField.
- rowState
- DataControlRowState
Uno dei valori di DataControlRowState.One of the DataControlRowState values.
- includeReadOnly
- Boolean
true
per indicare che i valori dei campi in sola lettura sono inclusi nell'insieme dictionary
; in caso contrario, false
.true
to indicate that the values of read-only fields are included in the dictionary
collection; otherwise, false
.
Esempio
Nell'esempio di codice seguente viene illustrato come implementare il ExtractValuesFromCell metodo per un controllo che deriva dalla DataControlField classe.The following code example demonstrates how to implement the ExtractValuesFromCell method for a control that derives from the DataControlField class. La RadioButtonField
classe esegue il rendering di un pulsante di opzione associato a dati per ogni riga in un GridView controllo.The RadioButtonField
class renders a data-bound radio button for every row in a GridView control. Quando ExtractValuesFromCell viene chiamato il metodo, il metodo tenta di determinare se il valore corrente dell' RadioButton oggetto contenuto nella cella è selezionato o deselezionato e aggiunge il valore alla IDictionary raccolta.When the ExtractValuesFromCell method is called, the method attempts to determine whether the current value of the RadioButton object contained in the cell is selected or cleared, and adds the value to the IDictionary collection. Questo esempio di codice fa parte di un esempio più ampio fornito per la DataControlField classe.This code example is part of a larger example provided for the DataControlField class.
// This method is called by the ExtractRowValues methods of
// GridView and DetailsView. Retrieve the current value of the
// cell from the Checked state of the Radio button.
public override void ExtractValuesFromCell(IOrderedDictionary dictionary,
DataControlFieldCell cell,
DataControlRowState rowState,
bool includeReadOnly)
{
// Determine whether the cell contains a RadioButton
// in its Controls collection.
if (cell.Controls.Count > 0) {
RadioButton radio = cell.Controls[0] as RadioButton;
object checkedValue = null;
if (null == radio) {
// A RadioButton is expected, but a null is encountered.
// Add error handling.
throw new InvalidOperationException
("RadioButtonField could not extract control.");
}
else {
checkedValue = radio.Checked;
}
// Add the value of the Checked attribute of the
// RadioButton to the dictionary.
if (dictionary.Contains(DataField))
dictionary[DataField] = checkedValue;
else
dictionary.Add(DataField, checkedValue);
}
}
' This method is called by the ExtractRowValues methods of
' GridView and DetailsView. Retrieve the current value of the
' cell from the Checked state of the Radio button.
Public Overrides Sub ExtractValuesFromCell( _
ByVal dictionary As IOrderedDictionary, _
ByVal cell As DataControlFieldCell, _
ByVal rowState As DataControlRowState, _
ByVal includeReadOnly As Boolean)
' Determine whether the cell contain a RadioButton
' in its Controls collection.
If cell.Controls.Count > 0 Then
Dim radio As RadioButton = CType(cell.Controls(0), RadioButton)
Dim checkedValue As Object = Nothing
If radio Is Nothing Then
' A RadioButton is expected, but a null is encountered.
' Add error handling.
Throw New InvalidOperationException( _
"RadioButtonField could not extract control.")
Else
checkedValue = radio.Checked
End If
' Add the value of the Checked attribute of the
' RadioButton to the dictionary.
If dictionary.Contains(DataField) Then
dictionary(DataField) = checkedValue
Else
dictionary.Add(DataField, checkedValue)
End If
End If
End Sub
Commenti
Il ExtractValuesFromCell metodo viene implementato dai tipi derivati da DataControlField per associare il campo corrente a un valore, se applicabile.The ExtractValuesFromCell method is implemented by types derived from DataControlField to associate the current field with a value, if applicable. La coppia campo/valore viene archiviata nella dictionary
raccolta passata al metodo.The field/value pair is stored in the dictionary
collection that is passed to the method. Il ExtractValuesFromCell metodo viene chiamato dal ExtractRowValues
metodo dei controlli dati, ad esempio DetailsView e GridView .The ExtractValuesFromCell method is called by the ExtractRowValues
method of data controls such as DetailsView and GridView.
Chiamare questo metodo quando si scrive un controllo con associazione a dati personalizzato che usa DataControlFieldCell oggetti per assemblare un set di celle e i relativi valori associati.Call this method when you are writing a custom data-bound control that uses DataControlFieldCell objects to assemble a set of cells and their associated values. Implementare questo metodo quando si scrive una classe derivata da DataControlField che Visualizza dati utente o dati associati a dati.Implement this method when you are writing a class derived from DataControlField that displays user data or data-bound data. Non tutti i tipi derivati implementano il ExtractValuesFromCell metodo, perché non tutti i campi visualizzano i dati utente.Not all derived types implement the ExtractValuesFromCell method, because not all fields display user data. Ad esempio, il ButtonField controllo Visualizza un pulsante e non contiene dati utente.For example, the ButtonField control displays a button and has no user data.