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//------------------------------------------------------------------------------
// <copyright file="ControlParameter.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.UI.WebControls {
using System;
using System.ComponentModel;
using System.Data;
using System.Web.UI.WebControls;
/// <devdoc>
/// Represents a Parameter that gets its value from a control's property.
/// </devdoc>
[
DefaultProperty("ControlID"),
]
public class ControlParameter : Parameter {
/// <devdoc>
/// Creates an instance of the ControlParameter class.
/// </devdoc>
public ControlParameter() {
}
/// <devdoc>
/// Creates an instance of the ControlParameter class with the specified parameter name and control ID.
/// </devdoc>
public ControlParameter(string name, string controlID) : base(name) {
ControlID = controlID;
}
/// <devdoc>
/// Creates an instance of the ControlParameter class with the specified parameter name, control ID, and property name.
/// </devdoc>
public ControlParameter(string name, string controlID, string propertyName) : base(name) {
ControlID = controlID;
PropertyName = propertyName;
}
/// <devdoc>
/// Creates an instance of the ControlParameter class with the specified parameter name, database type,
/// control ID, and property name.
/// </devdoc>
public ControlParameter(string name, DbType dbType, string controlID, string propertyName)
: base(name, dbType) {
ControlID = controlID;
PropertyName = propertyName;
}
/// <devdoc>
/// Creates an instance of the ControlParameter class with the specified parameter name, type, control ID, and property name.
/// </devdoc>
public ControlParameter(string name, TypeCode type, string controlID, string propertyName) : base(name, type) {
ControlID = controlID;
PropertyName = propertyName;
}
/// <devdoc>
/// Used to clone a parameter.
/// </devdoc>
protected ControlParameter(ControlParameter original) : base(original) {
ControlID = original.ControlID;
PropertyName = original.PropertyName;
}
/// <devdoc>
/// The ID of the control to get the value from.
/// </devdoc>
[
DefaultValue(""),
IDReferenceProperty(),
RefreshProperties(RefreshProperties.All),
TypeConverter(typeof(ControlIDConverter)),
WebCategory("Control"),
WebSysDescription(SR.ControlParameter_ControlID),
]
public string ControlID {
get {
object o = ViewState["ControlID"];
if (o == null)
return String.Empty;
return (string)o;
}
set {
if (ControlID != value) {
ViewState["ControlID"] = value;
OnParameterChanged();
}
}
}
/// <devdoc>
/// The name of the control's property to get the value from.
/// If none is specified, the ControlValueProperty attribute of the control will be examined to determine the default property name.
/// </devdoc>
[
DefaultValue(""),
TypeConverter(typeof(ControlPropertyNameConverter)),
WebCategory("Control"),
WebSysDescription(SR.ControlParameter_PropertyName),
]
public string PropertyName {
get {
object o = ViewState["PropertyName"];
if (o == null)
return String.Empty;
return (string)o;
}
set {
if (PropertyName != value) {
ViewState["PropertyName"] = value;
OnParameterChanged();
}
}
}
/// <devdoc>
/// Creates a new ControlParameter that is a copy of this ControlParameter.
/// </devdoc>
protected override Parameter Clone() {
return new ControlParameter(this);
}
/// <devdoc>
/// Returns the updated value of the parameter.
/// </devdoc>
protected internal override object Evaluate(HttpContext context, Control control) {
if (control == null) {
return null;
}
string controlID = ControlID;
string propertyName = PropertyName;
if (controlID.Length == 0) {
throw new ArgumentException(SR.GetString(SR.ControlParameter_ControlIDNotSpecified, Name));
}
Control foundControl = DataBoundControlHelper.FindControl(control, controlID);
if (foundControl == null) {
throw new InvalidOperationException(SR.GetString(SR.ControlParameter_CouldNotFindControl, controlID, Name));
}
ControlValuePropertyAttribute controlValueProp = (ControlValuePropertyAttribute)TypeDescriptor.GetAttributes(foundControl)[typeof(ControlValuePropertyAttribute)];
// If no property name is specified, use the ControlValuePropertyAttribute to determine which property to use.
if (propertyName.Length == 0) {
if ((controlValueProp != null) && (!String.IsNullOrEmpty(controlValueProp.Name))) {
propertyName = controlValueProp.Name;
}
else {
throw new InvalidOperationException(SR.GetString(SR.ControlParameter_PropertyNameNotSpecified, controlID, Name));
}
}
// Get the value of the property
object value = DataBinder.Eval(foundControl, propertyName);
// Convert the value to null if this is the default property and the value is the property's default value
if (controlValueProp != null &&
String.Equals(controlValueProp.Name, propertyName, StringComparison.OrdinalIgnoreCase) &&
controlValueProp.DefaultValue != null &&
controlValueProp.DefaultValue.Equals(value)) {
return null;
}
return value;
}
}
}
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