objectresult_tresulttype.cs source code in C# .NET

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                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Objects / objectresult_tresulttype.cs / 1305376 / objectresult_tresulttype.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner       [....]
// @backupowner [....] 
//--------------------------------------------------------------------- 

namespace System.Data.Objects 
{
    using System;
    using System.Collections;
    using System.Collections.Generic; 
    using System.Collections.ObjectModel;
    using System.ComponentModel; 
    using System.Data; 
    using System.Data.Common;
    using System.Data.Metadata.Edm; 
    using System.Data.Mapping;
    using System.Data.Objects.DataClasses;
    using System.Diagnostics;
    using System.Linq.Expressions; 
    using System.Data.Common.Internal.Materialization;
 
    ///  
    /// This class implements IEnumerable of T and IDisposable. Instance of this class
    /// is returned from ObjectQuery<T>.Execute method. 
    /// 
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix")]
    public sealed class ObjectResult : ObjectResult, IEnumerable
    { 
        private Shaper _shaper;
        private DbDataReader _reader; 
        private readonly EntitySet _singleEntitySet; 
        private readonly TypeUsage _resultItemType;
        private readonly bool _readerOwned; 
        private IBindingList _cachedBindingList;

        internal ObjectResult(Shaper shaper, EntitySet singleEntitySet, TypeUsage resultItemType)
            : this(shaper, singleEntitySet, resultItemType, true) 
        {
        } 
 
        internal ObjectResult(Shaper shaper, EntitySet singleEntitySet, TypeUsage resultItemType, bool readerOwned)
        { 
            _shaper = shaper;
            _reader = _shaper.Reader;
            _singleEntitySet = singleEntitySet;
            _resultItemType = resultItemType; 
            _readerOwned = readerOwned;
        } 
 
        private void EnsureCanEnumerateResults()
        { 
            if (null == _shaper)
            {
                // Enumerating more than once is not allowed.
                throw EntityUtil.CannotReEnumerateQueryResults(); 
            }
        } 
 
        /// 
        /// Returns an enumerator that iterates through the collection. 
        /// 
        public IEnumerator GetEnumerator()
        {
            EnsureCanEnumerateResults(); 

            Shaper shaper = _shaper; 
            _shaper = null; 
            IEnumerator result = shaper.GetEnumerator();
            return result; 
        }

        /// 
        /// Performs tasks associated with freeing, releasing, or resetting resources. 
        /// 
        public override void Dispose() 
        { 
            DbDataReader reader = _reader;
            _reader = null; 

            if (null != reader && _readerOwned)
            {
                reader.Dispose(); 
            }
            if (_shaper != null) 
            { 
                // This case includes when the ObjectResult is disposed before it
                // created an ObjectQueryEnumeration; at this time, the connection can be released 
                if (_shaper.Context != null && _readerOwned)
                {
                    _shaper.Context.ReleaseConnection();
                } 
                _shaper = null;
            } 
        } 

        internal override IEnumerator GetEnumeratorInternal() 
        {
            return ((IEnumerable)this).GetEnumerator();
        }
 
        internal override IList GetIListSourceListInternal()
        { 
            // You can only enumerate the query results once, and the creation of an ObjectView consumes this enumeration. 
            // However, there are situations where setting the DataSource of a control can result in multiple calls to this method.
            // In order to enable this scenario and allow direct binding to the ObjectResult instance, 
            // the ObjectView is cached and returned on subsequent calls to this method.

            if (_cachedBindingList == null)
            { 
                EnsureCanEnumerateResults();
 
                bool forceReadOnly = this._shaper.MergeOption == MergeOption.NoTracking; 
                _cachedBindingList = ObjectViewFactory.CreateViewForQuery(this._resultItemType, this, this._shaper.Context, forceReadOnly, this._singleEntitySet);
            } 

            return _cachedBindingList;
        }
 
        public override Type ElementType
        { 
            get { return typeof(T); } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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objectresult_tresulttype.cs source code in C# .NET

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