BindToObject.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / BindToObject.cs / 3 / BindToObject.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Windows.Forms { 
 
    using System;
    using Microsoft.Win32; 
    using System.Diagnostics;
    using System.ComponentModel;
    using System.ComponentModel.Design;
    using System.Collections; 

    internal class BindToObject { 
        private PropertyDescriptor fieldInfo; 
        private BindingMemberInfo dataMember;
        private Object dataSource; 
        private BindingManagerBase bindingManager;
        private Binding owner;
        private string errorText = string.Empty;
 
        private bool dataSourceInitialized = false;
        private bool waitingOnDataSource = false; 
 
        private void PropValueChanged(object sender, EventArgs e) {
            if(this.bindingManager != null) { 
                this.bindingManager.OnCurrentChanged(EventArgs.Empty);
            }
        }
 
        private bool IsDataSourceInitialized {
            get { 
                Debug.Assert(this.dataSource != null, "how can we determine if DataSource is initialized or not if we have no data source?"); 

                if (this.dataSourceInitialized) { 
                    return true;
                }

                ISupportInitializeNotification ds = this.dataSource as ISupportInitializeNotification; 
                if (ds == null || ds.IsInitialized) {
                    this.dataSourceInitialized = true; 
                    return true; 
                }
 
                // We have an ISupportInitializeNotification which was not initialized yet.

                // We already hooked up the Initialized event and the data source is not initialized yet.
                if (this.waitingOnDataSource) { 
                    return false;
                } 
 
                // Hook up the Initialized event.
                ds.Initialized += new EventHandler(DataSource_Initialized); 
                this.waitingOnDataSource = true;
                return false;
            }
        } 

        internal BindToObject(Binding owner, Object dataSource, string dataMember) { 
            this.owner = owner; 
            this.dataSource = dataSource;
            this.dataMember = new BindingMemberInfo(dataMember); 
            CheckBinding();
        }

        private void DataSource_Initialized(object sender, EventArgs e) { 
            Debug.Assert(sender == this.dataSource, "data source should not change");
            Debug.Assert(this.dataSource is ISupportInitializeNotification, "data source should not change on the BindToObject"); 
            Debug.Assert(this.waitingOnDataSource); 

            ISupportInitializeNotification ds = this.dataSource as ISupportInitializeNotification; 
            // Unhook the Initialized event.
            if (ds != null) {
                ds.Initialized -= new EventHandler(DataSource_Initialized);
            } 

            // The wait is over: DataSource is initialized. 
            this.waitingOnDataSource = false; 
            this.dataSourceInitialized = true;
 
            // Rebind.
            CheckBinding();
        }
 
        internal void SetBindingManagerBase(BindingManagerBase lManager) {
            if (bindingManager == lManager) 
            { 
                return;
            } 

            // remove notification from the backEnd
            if (bindingManager != null && fieldInfo != null && bindingManager.IsBinding && !(bindingManager is CurrencyManager)) {
                fieldInfo.RemoveValueChanged(bindingManager.Current, new EventHandler(PropValueChanged)); 
                fieldInfo = null;
            } 
 
            this.bindingManager = lManager;
            CheckBinding(); 
        }

        internal string DataErrorText
        { 
            get
            { 
                return this.errorText; 
            }
        } 

        // Returns any data error info on the data source for the bound data field in the current row
        string GetErrorText(object value) {
 
            IDataErrorInfo errorInfo = value as IDataErrorInfo;
            string text = string.Empty; 
 
            if (errorInfo != null) {
                // Get the row error if there is no DataMember 
                if (fieldInfo == null) {
                    text = errorInfo.Error;
                }
                // Get the column error if there is a DataMember. 
                // The DataTable uses its own Locale to lookup column names .
                // So passing the DataMember from the BindingField could cause problems. 
                // Pass the name from the PropertyDescriptor that the DataTable gave us. 
                // (If there is no fieldInfo, data binding would have failed already )
                else { 
                    text = errorInfo[fieldInfo.Name];
                }
            }
 
            return text ?? string.Empty;
        } 
 
        internal Object GetValue() {
            object obj = bindingManager.Current; 

            // Update IDataErrorInfo text: it's ok to get this now because we're going to need
            // this as part of the BindingCompleteEventArgs anyway.
            this.errorText = GetErrorText(obj); 

            if (fieldInfo != null) { 
               obj = fieldInfo.GetValue(obj); 
            }
 
            return obj;
        }

        internal Type BindToType { 
            get {
                if (dataMember.BindingField.Length == 0) { 
                    // if we are bound to a list w/o any properties, then 
                    // take the type from the BindingManager
                    Type type = this.bindingManager.BindType; 
                    if (typeof(Array).IsAssignableFrom(type))
                        type = type.GetElementType();
                    return type;
                } 
                else
                    return fieldInfo == null ? null : fieldInfo.PropertyType; 
            } 
        }
 
        internal void SetValue(Object value) {
            object obj = null;

            if (fieldInfo != null) { 
                obj = bindingManager.Current;
                if (obj is IEditableObject) 
                    ((IEditableObject) obj).BeginEdit(); 
                //(bug 112947) .. checkif the Column is readonly while pushing data...
                if (!fieldInfo.IsReadOnly) { 
                    fieldInfo.SetValue(obj, value);
                }

            } 
            else {
                CurrencyManager cm = bindingManager as CurrencyManager; 
                if (cm != null) 
                {
                    cm[cm.Position] = value; 
                    obj = value;
                }
            }
 
            // Update IDataErrorInfo text.
            this.errorText = GetErrorText(obj); 
        } 

        internal BindingMemberInfo BindingMemberInfo { 
            get {
                return this.dataMember;
            }
        } 

        internal Object DataSource { 
            get { 
                return dataSource;
            } 
        }

        internal PropertyDescriptor FieldInfo {
            get { 
                return fieldInfo;
            } 
        } 

        internal BindingManagerBase BindingManagerBase { 
            get {
                return this.bindingManager;
            }
        } 

        internal void CheckBinding() { 
 
            // At design time, don't check anything.
            // 
            if (owner != null &&
                owner.BindableComponent != null &&
                owner.ControlAtDesignTime()) {
 
                return;
            } 
 
            // force Column to throw if it's currently a bad column.
            //DataColumn tempColumn = this.Column; 

            // remove propertyChangedNotification when this binding is deleted
            if (this.owner.BindingManagerBase != null &&
                this.fieldInfo != null && 
                this.owner.BindingManagerBase.IsBinding &&
                !(this.owner.BindingManagerBase is CurrencyManager)) { 
 
                fieldInfo.RemoveValueChanged(owner.BindingManagerBase.Current, new EventHandler(PropValueChanged));
            } 

            if (owner != null &&
                owner.BindingManagerBase != null &&
                owner.BindableComponent != null && 
                owner.ComponentCreated &&
                this.IsDataSourceInitialized) { 
 
                string dataField = dataMember.BindingField;
 
                fieldInfo = owner.BindingManagerBase.GetItemProperties().Find(dataField, true);
                if (owner.BindingManagerBase.DataSource != null && fieldInfo == null && dataField.Length > 0) {
                    throw new ArgumentException(SR.GetString(SR.ListBindingBindField, dataField), "dataMember");
                } 

                // Do not add propertyChange notification if 
                // the fieldInfo is null 
                //
                // we add an event handler to the dataSource in the BindingManagerBase because 
                // if the binding is of the form (Control, ControlProperty, DataSource, Property1.Property2.Property3)
                // then we want to get notification from Current.Property1.Property2 and not from DataSource
                // when we get the backEnd notification we push the new value into the Control's property
                // 
                if (fieldInfo != null &&
                    owner.BindingManagerBase.IsBinding && 
                    !(this.owner.BindingManagerBase is CurrencyManager)) { 

                    fieldInfo.AddValueChanged(this.owner.BindingManagerBase.Current, new EventHandler(PropValueChanged)); 
                }
            }
            else {
                fieldInfo = null; 
            }
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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BindToObject.cs source code in C# .NET

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