EpmSyndicationContentSerializer.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataWeb / Client / System / Data / Services / Client / Epm / EpmSyndicationContentSerializer.cs / 1305376 / EpmSyndicationContentSerializer.cs
                        

                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//  
// Classes used for serializing EntityPropertyMappingAttribute content for
// syndication specific mappings 
//  
//
// @owner  [....] 
//---------------------------------------------------------------------

namespace System.Data.Services.Client
{ 
    using System.Data.Services.Common;
    using System.Diagnostics; 
    using System.Xml; 

    ///  
    /// Base visitor class for performing serialization of syndication specific content in the feed entry whose mapping
    /// is provided through EntityPropertyMappingAttributes
    /// 
    internal sealed class EpmSyndicationContentSerializer : EpmContentSerializerBase, IDisposable 
    {
        ///  
        /// Is author mapping provided in the target tree 
        /// 
        private bool authorInfoPresent; 

        /// 
        /// Is updated mapping provided in the target tree
        ///  
        private bool updatedPresent;
 
        ///  
        /// Is author name provided in the target tree
        ///  
        private bool authorNamePresent;

        /// 
        /// Constructor initializes the base class be identifying itself as a syndication serializer 
        /// 
        /// Target tree containing mapping information 
        /// Object to be serialized 
        /// SyndicationItem to which content will be added
        internal EpmSyndicationContentSerializer(EpmTargetTree tree, object element, XmlWriter target) 
            : base(tree, true, element, target)
        {
        }
 
        /// 
        /// Used for housecleaning once every node has been visited, creates an author and updated syndication elements if none 
        /// have been created by the visitor 
        /// 
        public void Dispose() 
        {
            this.CreateAuthor(true);
            this.CreateUpdated();
        } 

        ///  
        /// Override of the base Visitor method, which actually performs mapping search and serialization 
        /// 
        /// Current segment being checked for mapping 
        /// Which sub segments to serialize
        protected override void Serialize(EpmTargetPathSegment targetSegment, EpmSerializationKind kind)
        {
            if (targetSegment.HasContent) 
            {
                EntityPropertyMappingInfo epmInfo = targetSegment.EpmInfo; 
                Object propertyValue; 

                try 
                {
                    propertyValue = epmInfo.PropValReader.DynamicInvoke(this.Element);
                }
                catch (System.Reflection.TargetInvocationException) 
                {
                    throw; 
                } 

                String contentType; 
                Action contentWriter;

                switch (epmInfo.Attribute.TargetTextContentKind)
                { 
                    case SyndicationTextContentKind.Html:
                        contentType = "html"; 
                        contentWriter = this.Target.WriteString; 
                        break;
                    case SyndicationTextContentKind.Xhtml: 
                        contentType = "xhtml";
                        contentWriter = this.Target.WriteRaw;
                        break;
                    default: 
                        contentType = "text";
                        contentWriter = this.Target.WriteString; 
                        break; 
                }
 
                Action textSyndicationWriter = (c, nonTextPossible, atomDateConstruct) =>
                {
                    this.Target.WriteStartElement(c, XmlConstants.AtomNamespace);
                    if (nonTextPossible) 
                    {
                        this.Target.WriteAttributeString(XmlConstants.AtomTypeAttributeName, String.Empty, contentType); 
                    } 

                    // As per atomPub spec dateConstructs must contain valid datetime. Therefore we need to fill atom:updated/atom:published 
                    // field with something (e.g. DateTimeOffset.MinValue) if the user wants to map null to either of these fields. This will
                    // satisfy protocol requirements and Syndication API. Note that the content will still contain information saying that the
                    // mapped property is supposed to be null - therefore the server will know that the actual value sent by the user is null.
                    // For all other elements we can use empty string since the content is not validated. 
                    String textPropertyValue =
                        propertyValue != null   ? ClientConvert.ToString(propertyValue, atomDateConstruct) : 
                        atomDateConstruct       ? ClientConvert.ToString(DateTime.MinValue, atomDateConstruct) : 
                        String.Empty;
 
                    contentWriter(textPropertyValue);
                    this.Target.WriteEndElement();
                };
 
                switch (epmInfo.Attribute.TargetSyndicationItem)
                { 
                    case SyndicationItemProperty.AuthorEmail: 
                    case SyndicationItemProperty.ContributorEmail:
                        textSyndicationWriter(XmlConstants.AtomEmailElementName, false, false); 
                        break;
                    case SyndicationItemProperty.AuthorName:
                    case SyndicationItemProperty.ContributorName:
                        textSyndicationWriter(XmlConstants.AtomNameElementName, false, false); 
                        this.authorNamePresent = true;
                        break; 
                    case SyndicationItemProperty.AuthorUri: 
                    case SyndicationItemProperty.ContributorUri:
                        textSyndicationWriter(XmlConstants.AtomUriElementName, false, false); 
                        break;
                    case SyndicationItemProperty.Updated:
                        textSyndicationWriter(XmlConstants.AtomUpdatedElementName, false, true);
                        this.updatedPresent = true; 
                        break;
                    case SyndicationItemProperty.Published: 
                        textSyndicationWriter(XmlConstants.AtomPublishedElementName, false, true); 
                        break;
                    case SyndicationItemProperty.Rights: 
                        textSyndicationWriter(XmlConstants.AtomRightsElementName, true, false);
                        break;
                    case SyndicationItemProperty.Summary:
                        textSyndicationWriter(XmlConstants.AtomSummaryElementName, true, false); 
                        break;
                    case SyndicationItemProperty.Title: 
                        textSyndicationWriter(XmlConstants.AtomTitleElementName, true, false); 
                        break;
                    default: 
                        Debug.Assert(false, "Unhandled SyndicationItemProperty enum value - should never get here.");
                        break;
                }
            } 
            else
            { 
                if (targetSegment.SegmentName == XmlConstants.AtomAuthorElementName) 
                {
                    this.CreateAuthor(false); 
                    base.Serialize(targetSegment, kind);
                    this.FinishAuthor();
                }
                else if (targetSegment.SegmentName == XmlConstants.AtomContributorElementName) 
                {
                    this.Target.WriteStartElement(XmlConstants.AtomContributorElementName, XmlConstants.AtomNamespace); 
                    base.Serialize(targetSegment, kind); 
                    this.Target.WriteEndElement();
                } 
                else
                {
                    Debug.Assert(false, "Only authors and contributors have nested elements");
                } 
            }
        } 
 
        /// 
        /// Creates a new author syndication specific object 
        /// 
        /// Whether to create a null author or a non-null author
        private void CreateAuthor(bool createNull)
        { 
            if (!this.authorInfoPresent)
            { 
                if (createNull) 
                {
                    this.Target.WriteStartElement(XmlConstants.AtomAuthorElementName, XmlConstants.AtomNamespace); 
                    this.Target.WriteElementString(XmlConstants.AtomNameElementName, XmlConstants.AtomNamespace, String.Empty);
                    this.Target.WriteEndElement();
                }
                else 
                {
                    this.Target.WriteStartElement(XmlConstants.AtomAuthorElementName, XmlConstants.AtomNamespace); 
                } 

                this.authorInfoPresent = true; 
            }
        }

        ///  
        /// Finish writing the author atom element
        ///  
        private void FinishAuthor() 
        {
            Debug.Assert(this.authorInfoPresent == true, "Must have already written the start element for author"); 
            if (this.authorNamePresent == false)
            {
                this.Target.WriteElementString(XmlConstants.AtomNameElementName, XmlConstants.AtomNamespace, String.Empty);
                this.authorNamePresent = true; 
            }
 
            this.Target.WriteEndElement(); 
        }
 
        /// 
        /// Ensures that mandatory atom:update element is creatd. The value of the created element is set to with value set to DateTime.UtcNow.
        /// This method is used only if there are some EPM mappings for the given resource type but there is no mapping to atom:updated
        /// element. Otherwise the element will be created during mapping handling or if there is no EPM mapping at all during the serialization. 
        /// 
        private void CreateUpdated() 
        { 
            if (!this.updatedPresent)
            { 
                this.Target.WriteElementString(XmlConstants.AtomUpdatedElementName, XmlConstants.AtomNamespace, XmlConvert.ToString(DateTime.UtcNow, XmlDateTimeSerializationMode.RoundtripKind));
            }
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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