Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/UI/DataSourceHelper.cs

@@ -0,0 +1,76 @@
+//------------------------------------------------------------------------------
+// <copyright file="DataSourceHelper.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.UI {
+
+    using System;
+    using System.Collections;
+    using System.ComponentModel;
+    using System.ComponentModel.Design;
+    using System.Data;
+
+    internal sealed class DataSourceHelper {
+
+        private DataSourceHelper() {
+        }
+
+        internal static IEnumerable GetResolvedDataSource(object dataSource, string dataMember) {
+            if (dataSource == null)
+                return null;
+
+            IListSource listSource = dataSource as IListSource;
+            if (listSource != null) {
+                IList memberList = listSource.GetList();
+
+                if (listSource.ContainsListCollection == false) {
+                    // the returned list is itself the list we need to bind to
+                    // NOTE: I am ignoring the DataMember parameter... ideally we might have
+                    //       thrown an exception, but this would mess up design-time usage
+                    //       where the user may change the data source from a DataSet to a
+                    //       DataTable.
+                    return (IEnumerable)memberList;
+                }
+
+                if ((memberList != null) && (memberList is ITypedList)) {
+                    ITypedList typedMemberList = (ITypedList)memberList;
+
+                    PropertyDescriptorCollection propDescs = typedMemberList.GetItemProperties(new PropertyDescriptor[0]);
+                    if ((propDescs != null) && (propDescs.Count != 0)) {
+                        PropertyDescriptor listProperty = null;
+
+                        if (String.IsNullOrEmpty(dataMember)) {
+                            listProperty = propDescs[0];
+                        }
+                        else {
+                            listProperty = propDescs.Find(dataMember, true);
+                        }
+
+                        if (listProperty != null) {
+                            object listRow = memberList[0];
+                            object list = listProperty.GetValue(listRow);
+
+                            if ((list != null) && (list is IEnumerable)) {
+                                return (IEnumerable)list;
+                            }
+                        }
+
+                        throw new HttpException(SR.GetString(SR.ListSource_Missing_DataMember, dataMember));
+                    }
+                    else {
+                        throw new HttpException(SR.GetString(SR.ListSource_Without_DataMembers));
+                    }
+                }
+            }
+
+            if (dataSource is IEnumerable) {
+                return (IEnumerable)dataSource;
+            }
+
+            return null;
+        }
+    }
+}
+