mcs/class/Facades/System.Data.Common/DbDataReaderExtensions.Facade.cs

   1 // Licensed to the .NET Foundation under one or more agreements.
   2 // The .NET Foundation licenses this file to you under the MIT license.
   3 // See the LICENSE file in the project root for more information.
   4
   5 using System.Collections.Generic;
   6
   7 namespace System.Data.Common
   8 {
   9
  10     internal class DataRowDbColumn : DbColumn
  11     {
  12         private DataColumnCollection schemaColumns;
  13         private DataRow schemaRow;
  14
  15         public DataRowDbColumn(DataRow readerSchemaRow, DataColumnCollection readerSchemaColumns)
  16         {
  17             this.schemaRow = readerSchemaRow;
  18             this.schemaColumns = readerSchemaColumns;
  19             populateFields();
  20         }
  21
  22         private void populateFields()
  23         {
  24             AllowDBNull = GetDbColumnValue<bool?>(SchemaTableColumn.AllowDBNull);
  25             BaseCatalogName = GetDbColumnValue<string>(SchemaTableOptionalColumn.BaseCatalogName);
  26             BaseColumnName = GetDbColumnValue<string>(SchemaTableColumn.BaseColumnName);
  27             BaseSchemaName = GetDbColumnValue<string>(SchemaTableColumn.BaseSchemaName);
  28             BaseServerName = GetDbColumnValue<string>(SchemaTableOptionalColumn.BaseServerName);
  29             BaseTableName = GetDbColumnValue<string>(SchemaTableColumn.BaseTableName);
  30             ColumnName = GetDbColumnValue<string>(SchemaTableColumn.ColumnName);
  31             ColumnOrdinal = GetDbColumnValue<int?>(SchemaTableColumn.ColumnOrdinal);
  32             ColumnSize = GetDbColumnValue<int?>(SchemaTableColumn.ColumnSize);
  33             IsAliased = GetDbColumnValue<bool?>(SchemaTableColumn.IsAliased);
  34             IsAutoIncrement = GetDbColumnValue<bool?>(SchemaTableOptionalColumn.IsAutoIncrement);
  35             IsExpression = GetDbColumnValue<bool>(SchemaTableColumn.IsExpression);
  36             IsHidden = GetDbColumnValue<bool?>(SchemaTableOptionalColumn.IsHidden);
  37             IsIdentity = GetDbColumnValue<bool?>("IsIdentity");
  38             IsKey = GetDbColumnValue<bool?>(SchemaTableColumn.IsKey);
  39             IsLong = GetDbColumnValue<bool?>(SchemaTableColumn.IsLong);
  40             IsReadOnly = GetDbColumnValue<bool?>(SchemaTableOptionalColumn.IsReadOnly);
  41             IsUnique = GetDbColumnValue<bool?>(SchemaTableColumn.IsUnique);
  42             NumericPrecision = GetDbColumnValue<int?>(SchemaTableColumn.NumericPrecision);
  43             NumericScale = GetDbColumnValue<int?>(SchemaTableColumn.NumericScale);
  44             UdtAssemblyQualifiedName = GetDbColumnValue<string>("UdtAssemblyQualifiedName");
  45             DataType = GetDbColumnValue<Type>(SchemaTableColumn.DataType);
  46             DataTypeName = GetDbColumnValue<string>("DataTypeName");
  47         }
  48
  49         private T GetDbColumnValue<T>(string columnName)
  50         {
  51             if (!schemaColumns.Contains(columnName))
  52             {
  53                 return default(T);
  54             }
  55             object schemaObject = schemaRow[columnName];
  56             if (schemaObject is T)
  57             {
  58                 return (T)schemaObject;
  59             }
  60             return default(T);
  61         }
  62     }
  63
  64     public static class DbDataReaderExtensions
  65     {
  66         public static System.Collections.ObjectModel.ReadOnlyCollection<DbColumn> GetColumnSchema(this DbDataReader reader)
  67         {
  68             IList<DbColumn> columnSchema = new List<DbColumn>();
  69             DataTable schemaTable = reader.GetSchemaTable();
  70             DataColumnCollection schemaTableColumns = schemaTable.Columns;
  71             foreach (DataRow row in schemaTable.Rows)
  72             {
  73                 DbColumn dbColumn = new DataRowDbColumn(row, schemaTableColumns);
  74                 columnSchema.Add(dbColumn);
  75             }
  76             System.Collections.ObjectModel.ReadOnlyCollection<DbColumn> readOnlyColumnSchema = new System.Collections.ObjectModel.ReadOnlyCollection<DbColumn>(columnSchema);
  77             return readOnlyColumnSchema;
  78         }
  79
  80         public static bool CanGetColumnSchema(this DbDataReader reader)
  81         {
  82             return true;
  83         }
  84     }
  85 }