RelatedCurrencyManager.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / RelatedCurrencyManager.cs / 1 / RelatedCurrencyManager.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

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

    ///  
    ///  
    /// Represents the child version of the System.Windows.Forms.ListManager
    /// that is used when a parent/child relationship exists in a System.Windows.Forms.DataSet. 
    /// 
    internal class RelatedCurrencyManager : CurrencyManager {

        BindingManagerBase parentManager; 
        string dataField;
        PropertyDescriptor fieldInfo; 
        bool ignoreParentCurrentItemChanged = false; 

        [ 
            SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")  // If the constructor does not set the dataSource
                                                                                                    // it would be a breaking change.
        ]
        internal RelatedCurrencyManager(BindingManagerBase parentManager, string dataField) : base(null) { 
            Bind(parentManager, dataField);
        } 
 
        internal void Bind(BindingManagerBase parentManager, string dataField) {
            Debug.Assert(parentManager != null, "How could this be a null parentManager."); 

            // Unwire previous BindingManagerBase
            UnwireParentManager(this.parentManager);
 
            this.parentManager = parentManager;
            this.dataField = dataField; 
            this.fieldInfo = parentManager.GetItemProperties().Find(dataField, true); 
            if (fieldInfo == null || !typeof(IList).IsAssignableFrom(fieldInfo.PropertyType)) {
                throw new ArgumentException(SR.GetString(SR.RelatedListManagerChild, dataField)); 
            }
            this.finalType = fieldInfo.PropertyType;

            // Wire new BindingManagerBase 
            WireParentManager(this.parentManager);
 
            ParentManager_CurrentItemChanged(parentManager, EventArgs.Empty); 
        }
 
        private void UnwireParentManager(BindingManagerBase bmb) {
            if (bmb != null) {
                bmb.CurrentItemChanged -= new EventHandler(ParentManager_CurrentItemChanged);
 
                if (bmb is CurrencyManager) {
                    (bmb as CurrencyManager).MetaDataChanged -= new EventHandler(ParentManager_MetaDataChanged); 
                } 
            }
        } 

        private void WireParentManager(BindingManagerBase bmb) {
            if (bmb != null) {
                bmb.CurrentItemChanged += new EventHandler(ParentManager_CurrentItemChanged); 

                if (bmb is CurrencyManager) { 
                    (bmb as CurrencyManager).MetaDataChanged += new EventHandler(ParentManager_MetaDataChanged); 
                }
            } 
        }

        internal override PropertyDescriptorCollection GetItemProperties(PropertyDescriptor[] listAccessors) {
            PropertyDescriptor[] accessors; 

            if (listAccessors != null && listAccessors.Length > 0) { 
                accessors = new PropertyDescriptor[listAccessors.Length + 1]; 
                listAccessors.CopyTo(accessors, 1);
            } 
            else {
                accessors = new PropertyDescriptor[1];
            }
 
            // Set this accessor (add to the beginning)
            accessors[0] = this.fieldInfo; 
 
            // Get props
            return parentManager.GetItemProperties(accessors); 
        }

        /// 
        ///  
        ///    Gets the properties of the item.
        ///  
        public override PropertyDescriptorCollection GetItemProperties() { 
            return GetItemProperties(null);
        } 

        // 
        //    Gets the name of the list.
        //  
        internal override string GetListName() {
            string name = GetListName(new ArrayList()); 
            if (name.Length > 0) { 
                return name;
            } 
            return base.GetListName();
        }

        ///  
        /// 
        ///    Gets the name of the specified list. 
        ///  
        protected internal override string GetListName(ArrayList listAccessors) {
            listAccessors.Insert(0, fieldInfo); 
            return parentManager.GetListName(listAccessors);
        }

        private void ParentManager_MetaDataChanged(object sender, EventArgs e) { 
            // Propagate MetaDataChanged events from the parent manager
            base.OnMetaDataChanged(e); 
        } 

        private void ParentManager_CurrentItemChanged(object sender, EventArgs e) { 
            if (this.ignoreParentCurrentItemChanged) {
                return;
            }
 
            int oldlistposition = this.listposition;
 
            // we only pull the data from the controls into the backEnd. we do not care about keeping the lastGoodKnownRow 
            // when we are about to change the entire list in this currencymanager.
            try { 
                PullData();
            }
            catch (Exception ex) {
                OnDataError(ex); 
            }
 
            if (parentManager is CurrencyManager) { 
                CurrencyManager curManager = (CurrencyManager) parentManager;
                if (curManager.Count > 0) { 
                    // Parent list has a current row, so get the related list from the relevant property on that row.
                    SetDataSource(fieldInfo.GetValue(curManager.Current));
                    listposition = (Count > 0 ? 0 : -1);
                } else { 
                    // APPCOMPAT: bring back the Everett behavior where the currency manager adds an item and
                    // then it cancels the addition. 
                    // vsw 427731. 
                    //
                    // really, really hocky. 
                    // will throw if the list in the curManager is not IBindingList
                    // and this will fail if the IBindingList does not have list change notification. read on....
                    // when a new item will get added to an empty parent table,
                    // the table will fire OnCurrentChanged and this method will get executed again 
                    // allowing us to set the data source to an object with the right properties (so we can show
                    // metadata at design time). 
                    // we then call CancelCurrentEdit to remove the dummy row, but making sure to ignore any 
                    // OnCurrentItemChanged that results from this action (to avoid infinite recursion)
                    curManager.AddNew(); 
                    try {
                        this.ignoreParentCurrentItemChanged = true;
                        curManager.CancelCurrentEdit();
                    } finally { 
                        this.ignoreParentCurrentItemChanged = false;
                    } 
                } 
            } else {
                // Case where the parent is not a list, but a single object 
                SetDataSource(fieldInfo.GetValue(parentManager.Current));
                listposition = (Count > 0 ? 0 : -1);
            }
            if (oldlistposition != listposition) 
                OnPositionChanged(EventArgs.Empty);
            OnCurrentChanged(EventArgs.Empty); 
            OnCurrentItemChanged(EventArgs.Empty); 
        }
 
    }
}

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

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