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//------------------------------------------------------------------------------
// <copyright file="LookupNode.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">[....]</owner>
// <owner current="true" primary="false">[....]</owner>
// <owner current="false" primary="false">[....]</owner>
//------------------------------------------------------------------------------
namespace System.Data {
using System;
using System.ComponentModel;
using System.Collections.Generic;
using System.Diagnostics;
internal sealed class LookupNode : ExpressionNode {
private readonly string relationName; // can be null
private readonly string columnName;
private DataColumn column;
private DataRelation relation;
internal LookupNode(DataTable table, string columnName, string relationName) : base(table) {
this.relationName = relationName;
this.columnName = columnName;
}
internal override void Bind(DataTable table, List<DataColumn> list) {
BindTable(table);
column = null; // clear for rebinding (if original binding was valid)
relation = null;
if (table == null)
throw ExprException.ExpressionUnbound(this.ToString());
// First find parent table
DataRelationCollection relations;
relations = table.ParentRelations;
if (relationName == null) {
// must have one and only one relation
if (relations.Count > 1) {
throw ExprException.UnresolvedRelation(table.TableName, this.ToString());
}
relation = relations[0];
}
else {
relation = relations[relationName];
}
if (null == relation) {
throw ExprException.BindFailure(relationName);// WebData 112162: this operation is not clne specific, throw generic exception
}
DataTable parentTable = relation.ParentTable;
Debug.Assert(relation != null, "Invalid relation: no parent table.");
Debug.Assert(columnName != null, "All Lookup expressions have columnName set.");
this.column = parentTable.Columns[columnName];
if (column == null)
throw ExprException.UnboundName(columnName);
// add column to the dependency list
int i;
for (i = 0; i < list.Count; i++) {
// walk the list, check if the current column already on the list
DataColumn dataColumn = list[i];
if (column == dataColumn) {
break;
}
}
if (i >= list.Count) {
list.Add(column);
}
// SQLBU 383715: Staleness of computed values in expression column as the relationship end columns are not being added to the dependent column list.
AggregateNode.Bind(relation, list);
}
internal override object Eval() {
throw ExprException.EvalNoContext();
}
internal override object Eval(DataRow row, DataRowVersion version) {
if (column == null || relation == null)
throw ExprException.ExpressionUnbound(this.ToString());
DataRow parent = row.GetParentRow(relation, version);
if (parent == null)
return DBNull.Value;
return parent[column, parent.HasVersion(version) ? version : DataRowVersion.Current]; // [....] : Bug 76154
}
internal override object Eval(int[] recordNos) {
throw ExprException.ComputeNotAggregate(this.ToString());
}
internal override bool IsConstant() {
return false;
}
internal override bool IsTableConstant() {
return false;
}
internal override bool HasLocalAggregate() {
return false;
}
internal override bool HasRemoteAggregate() {
return false;
}
internal override bool DependsOn(DataColumn column) {
if (this.column == column) {
return true;
}
return false;
}
internal override ExpressionNode Optimize() {
return this;
}
}
}
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