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Deserialization Error: The XML element 'name' from namespace '' is already present in the current scope

由 血红的双手。 提交于 2019-12-18 04:55:10

问题


This is my first time using XML Serialization and this is driving me absolutely nuts after 2 days of trying to troubleshoot this.

I get this error when the deserialization kicks in:

The XML element 'name' from namespace '' is already present in the current scope. Use XML attributes to specify another XML name or namespace for the element.

The error happens on this line in my code:

Album album = (Album)serializer.Deserialize(reader);

I not sure why. There is no dup "name" node so I just don't get it. This is an XML doc received from an HttpWebResponse from a 3rd party REST API.

Here's the complete code:

My Album Class (the type I'm Deserializing to):

    public class Album
    {
        #region Constructors

        public Album() 
        { 

        }

        #endregion

        #region ElementConstants

        public static class ElementConstants
        {
            public const string aID = "aid";
            public const string Owner = "owner";
            public const string AlbumName = "name";
            public const string CoverPhotoID = "cover_pid";
            public const string CreateDate = "created";
            public const string LastModifiedDate = "modified";
            public const string Description = "description";
            public const string Location = "location";
            public const string AlbumURL = "link";
            public const string Size = "size";
            public const string Visible = "visible";
        }

        #endregion ElementConstants

        #region Public Properties

        [XmlArray(ElementName = "photos_GetAlbums_response")]
        [XmlArrayItem( "album" )]
        public Album[] Albums { get; set; }

        [XmlElement (ElementName = ElementConstants.AlbumName, DataType = "string")]
        public string AlbumID { get; set; }

        [XmlElement(ElementName = ElementConstants.aID, DataType = "int")]
        public Int32 CoverPhotoID { get; set; }

        [XmlElement(ElementName = ElementConstants.Owner, DataType = "string")]
        public string Owner { get; set; }

        [XmlElement(ElementName = ElementConstants.AlbumName, DataType = "string")]
        public string AlbumName { get; set; }

        [XmlElement(ElementName = ElementConstants.aID, DataType = "DateTime")]
        public DateTime CreateDate { get; set; }

        [XmlElement(ElementName = ElementConstants.LastModifiedDate, DataType = "DateTime")]
        public DateTime LastModifiedDate { get; set; }

        [XmlElement(ElementName = ElementConstants.Description, DataType = "string")]
        public string Description { get; set; }

        [XmlElement(ElementName = ElementConstants.Location, DataType = "string")]
        public string Location { get; set; }

        [XmlElement(ElementName = ElementConstants.AlbumURL, DataType = "string")]
        public string Link { get; set; }

        [XmlElement(ElementName = ElementConstants.Size, DataType = "size")]
        public string Size { get; set; }

        [XmlElement(ElementName = ElementConstants.Visible, DataType = "string")]
        public string Visible { get; set; }

        #endregion
    }

My Serializer Class:

    public class Serializer
    {
        public static Album CreateAlbumFromXMLDoc(XmlDocument doc)
        {
            // Create an instance of a serializer
            var serializer = new XmlSerializer(typeof(Album));
            var reader = new StringReader(doc.ToString());

            // Deserialize the Xml Object and cast to type Album
            Album album = (Album)serializer.Deserialize(reader);

            return album;
        }
    }

The XML that I am trying to Deserialized (copied from the Xml Doc object being passed into the CreateAlbumFromXMLDoc method when debugging in VS):

<?xml version="1.0" encoding="UTF-8"?>
<photos_GetAlbums_response xsi:schemaLocation="http://api.example.com/1.0/ http://api.example.com/1.0/xxx.xsd" list="true">
<album>
 <aid>3231990241086938677</aid>
 <cover_pid>7031990241087042549</cover_pid>
 <owner>1337262814</owner>
 <name>LA</name>
 <created>1233469624</created>
 <modified>1233469942</modified>
 <description>trip to LA</description>
 <location>CA</location>
 <link>http://www.example.com/album.php?aid=7333&id=1337262814</link>
 <size>48</size>
 <visible>friends</visible>
 </album>
<album>
 <aid>7031990241086936240</aid>
 <cover_pid>7031990241087005994</cover_pid>
 <owner>1337262814</owner>
 <name>Wall Photos</name>
 <created>1230437805</created>
 <modified>1233460690</modified>
 <description/>
 <location/>
 <link>http://www.example.com/album.php?aid=3296&id=1337262814</link>
 <size>34</size>
 <visible>everyone</visible>
 </album>
<album>
 <aid>7031990241086937544</aid>
 <cover_pid>7031990241087026027</cover_pid>
 <owner>1337262814</owner>
 <name>Mobile Uploads</name>
 <created>1231984989</created>
 <modified>1233460349</modified>
 <description/>
 <location/>
 <link>http://www.example.com/album.php?aid=6300&id=1337262814</link>
 <size>3</size>
 <visible>friends</visible>
 </album>
<album>
 <aid>7031990241086936188</aid>
 <cover_pid>7031990241087005114</cover_pid>
 <owner>1337262814</owner>
 <name>Christmas 2008</name>
 <created>1230361978</created>
 <modified>1230362306</modified>
 <description>My Album</description>
 <location/>
 <link>http://www.example.com/album.php?aid=5234&id=1337262814</link>
 <size>50</size>
 <visible>friends</visible>
 </album>
<album>
 <aid>7031990241086935881</aid>
 <cover_pid>7031990241087001093</cover_pid>
 <owner>1637262814</owner>
 <name>Hock</name>
 <created>1229889219</created>
 <modified>1229889235</modified>
 <description>Misc Pics</description>
 <location/>
 <link>http://www.example.com/album.php?aid=4937&id=1637262814</link>
 <size>1</size>
 <visible>friends-of-friends</visible>
 </album>
<album>
 <aid>7031990241086935541</aid>
 <cover_pid>7031990241086996817</cover_pid>
 <owner>1637262814</owner>
 <name>Test Album 2 (for work)</name>
 <created>1229460455</created>
 <modified>1229460475</modified>
 <description>this is a test album</description>
 <location/>
 <link>http://www.example.com/album.php?aid=4547&id=1637262814</link>
 <size>1</size>
 <visible>everyone</visible>
 </album>
<album>
 <aid>7031990241086935537</aid>
 <cover_pid>7031990241086996795</cover_pid>
 <owner>1637262814</owner>
 <name>Test Album (for work)</name>
 <created>1229459168</created>
 <modified>1229459185</modified>
 <description>Testing for work</description>
 <location/>
 <link>http://www.example.com/album.php?aid=4493&id=1637262814</link>
 <size>1</size>
 <visible>friends</visible>
 </album>
 </photos_GetAlbums_response>

A side note: Just for the hell of it, I paste that XML into XML Notepad 2007, it tells me:

Your XML document contains no xml-stylesheet processing instruction. To provide an XSLT transform, add the following to the top of your file and edit the href attribute accordingly:

I don't think that really means it's malformed or anything but just something to note.

So..

My ultimate goal is to get pass this damn error obviously and get an array of albums back using my code above once I can get past the error. I also want to make sure my code is correct in trying to retrieve that arrray back of albums using my Album[] property in my Album class or anything else I might be missing here. I think it's pretty close and should work but it's not.

Follow-up. I've been pulling my hair out since then.

Here's the latest. I did not use some things for now (from Marc) like the Enum, etc. I might change that later. I also pulled out the datetime stuff as it just looked wierd and I did not get errors on that anway without...at least yet. The main problem now is still my damn XML.

It's still appearing to have problems with the format I guess? Unless it's covering up another problem, no clue. This is driving me fing crazy.

I now get this error when the deserialization kicks in:

Data at the root level is invalid. Line 1, position 1.

The error happens on this line in my code: GetAlbumsResponse album = (GetAlbumsResponse)serializer.Deserialize(reader);

How I get the response into an XmL doc:

public static XmlDocument GetResponseXmlDocument(HttpWebResponse response)
        {
            Stream dataStream = null; // stream from WebResponse
            XmlDocument doc = new XmlDocument();

            if (doc == null)
            {
                throw new NullReferenceException("The web reponse was null");
            }

            // Get the response stream so we can read the body of the response
            dataStream = response.GetResponseStream();

            // Open the stream using a StreamReader for easy access
            StreamReader reader = new StreamReader(dataStream);

            // Load response into string variable so that we can then load into an XML doc
            string responseString = reader.ReadToEnd();

            // Create an XML document & load it with the response data
            doc.LoadXml(responseString);

            // Final XML document that represents the response
            return doc;
        }

My Album Class & Root Level Class (thanks to help from Marc..I get it now):

namespace xxx.Entities
{

    [Serializable, XmlRoot("photos_GetAlbums_response")]
    public class GetAlbumsResponse
    {
        [XmlElement("album")]
        public List<Album> Albums { get; set; }

        [XmlAttribute("list")]
        public bool IsList { get; set; }
    }

    public class Album
    {
        #region Constructors

        public Album()
        {

        }

        #endregion

        #region ElementConstants

        /// <summary>
        /// Constants Class to eliminate use of Magic Strings (hard coded strings)
        /// </summary>
        public static class ElementConstants
        {
            public const string aID = "aid";
            public const string Owner = "owner";
            public const string AlbumName = "name";
            public const string CoverPhotoID = "cover_pid";
            public const string CreateDate = "created";
            public const string LastModifiedDate = "modified";
            public const string Description = "description";
            public const string Location = "location";
            public const string AlbumURL = "link";
            public const string Size = "size";
            public const string Visible = "visible";
        }

        #endregion ElementConstants

        #region Public Properties

        [XmlElement (ElementName = ElementConstants.aID, DataType = "string")]
        public string AlbumID { get; set; }

        [XmlElement(ElementName = ElementConstants.CoverPhotoID, DataType = "int")]
        public Int32 CoverPhotoID { get; set; }

        [XmlElement(ElementName = ElementConstants.Owner, DataType = "string")]
        public string Owner { get; set; }

        [XmlElement(ElementName = ElementConstants.AlbumName, DataType = "string")]
        public string AlbumName { get; set; }

        public string Created { get; set; }

        public DateTime Modified { get; set; }

        [XmlElement(ElementName = ElementConstants.Description, DataType = "string")]
        public string Description { get; set; }

        [XmlElement(ElementName = ElementConstants.Location, DataType = "string")]
        public string Location { get; set; }

        [XmlElement(ElementName = ElementConstants.AlbumURL, DataType = "string")]
        public string Link { get; set; }

        public string Size { get; set; }

        [XmlElement(ElementName = ElementConstants.Visible, DataType = "string")]
        public string Visible { get; set; }

        #endregion
    }
}

My Serializer Class:

namespace xxx.Utilities
{
    public class Serializer
    {
        public static List<Album> CreateAlbumFromXMLDoc(XmlDocument doc)
        {
            // Create an instance of a serializer
            var serializer = new XmlSerializer(typeof(Album));
            var reader = new StringReader(doc.ToString());

            // Deserialize the Xml Object and cast to type Album
            GetAlbumsResponse album = (GetAlbumsResponse)serializer.Deserialize(reader);

            return album.Albums;
        }
    }
}

The true XML incoming, that I am trying to Deserialize (yes it does have xmlns):

<?xml version="1.0" encoding="UTF-8"?>
<photos_GetAlbums_response xmlns="http://api.example.com/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://api.example.com/1.0/ http://api.example.com/1.0/xxx.xsd" list="true">
  <album>
    <aid>7321990241086938677</aid>
    <cover_pid>7031990241087042549</cover_pid>
    <owner>1124262814</owner>
    <name>Album Test 1</name>
    <created>1233469624</created>
    <modified>1233469942</modified>
    <description>Our trip</description>
    <location>CA</location>
    <link>http://www.example.com/album.php?aid=7733&id=1124262814</link>
    <size>48</size>
    <visible>friends</visible>
  </album>
  <album>
    <aid>231990241086936240</aid>
    <cover_pid>7042330241087005994</cover_pid>
    <owner>1124262814</owner>
    <name>Album Test 2</name>
    <created>1230437805</created>
    <modified>1233460690</modified>
    <description />
    <location />
    <link>http://www.example.com/album.php?aid=5296&id=1124262814</link>
    <size>34</size>
    <visible>everyone</visible>
  </album>
  <album>
    <aid>70319423341086937544</aid>
    <cover_pid>7032390241087026027</cover_pid>
    <owner>1124262814</owner>
    <name>Album Test 3</name>
    <created>1231984989</created>
    <modified>1233460349</modified>
    <description />
    <location />
    <link>http://www.example.com/album.php?aid=6600&id=1124262814</link>
    <size>3</size>
    <visible>friends</visible>
  </album>
</photos_GetAlbums_response>

回答1:


Personally, I wouldn't use constants here - they make it hard to spot errors (and since you probably aren't re-using them, don't add much). For example:

    [XmlElement (ElementName = ElementConstants.AlbumName, DataType = "string")]
    public string AlbumID { get; set; }
...
    [XmlElement(ElementName = ElementConstants.AlbumName, DataType = "string")]
    public string AlbumName { get; set; }

Looks suspect to me...

An easier approach is to write the xml you want to a file (foo.xml, say) and use:

xsd foo.xml
xsd foo.xsd /classes

Then look at foo.cs.




回答2:


Here we go... note the xml was invalid (& should be &amp;; use of undeclared xsi namespace-alias). Note also that I added an enum for the visibility, added handling for converting the long to DateTime, and added the wrapper type:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Xml;
using System.Xml.Serialization;

static class Program
{
    const string xml = @"<?xml version=""1.0"" encoding=""UTF-8""?>
<photos_GetAlbums_response
    xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance""
    xsi:schemaLocation=""http://api.example.com/1.0/ http://api.example.com/1.0/xxx.xsd""
    list=""true"">
<album>
 <aid>3231990241086938677</aid>
 <cover_pid>7031990241087042549</cover_pid>
 <owner>1337262814</owner>
 <name>LA</name>
 <created>1233469624</created>
 <modified>1233469942</modified>
 <description>trip to LA</description>
 <location>CA</location>
 <link>http://www.example.com/album.php?aid=7333&amp;id=1337262814</link>
 <size>48</size>
 <visible>friends</visible>
 </album>
<album>
 <aid>7031990241086936240</aid>
 <cover_pid>7031990241087005994</cover_pid>
 <owner>1337262814</owner>
 <name>Wall Photos</name>
 <created>1230437805</created>
 <modified>1233460690</modified>
 <description/>
 <location/>
 <link>http://www.example.com/album.php?aid=3296&amp;id=1337262814</link>
 <size>34</size>
 <visible>everyone</visible>
 </album>
<album>
 <aid>7031990241086937544</aid>
 <cover_pid>7031990241087026027</cover_pid>
 <owner>1337262814</owner>
 <name>Mobile Uploads</name>
 <created>1231984989</created>
 <modified>1233460349</modified>
 <description/>
 <location/>
 <link>http://www.example.com/album.php?aid=6300&amp;id=1337262814</link>
 <size>3</size>
 <visible>friends</visible>
 </album>
<album>
 <aid>7031990241086936188</aid>
 <cover_pid>7031990241087005114</cover_pid>
 <owner>1337262814</owner>
 <name>Christmas 2008</name>
 <created>1230361978</created>
 <modified>1230362306</modified>
 <description>My Album</description>
 <location/>
 <link>http://www.example.com/album.php?aid=5234&amp;id=1337262814</link>
 <size>50</size>
 <visible>friends</visible>
 </album>
<album>
 <aid>7031990241086935881</aid>
 <cover_pid>7031990241087001093</cover_pid>
 <owner>1637262814</owner>
 <name>Hock</name>
 <created>1229889219</created>
 <modified>1229889235</modified>
 <description>Misc Pics</description>
 <location/>
 <link>http://www.example.com/album.php?aid=4937&amp;id=1637262814</link>
 <size>1</size>
 <visible>friends-of-friends</visible>
 </album>
<album>
 <aid>7031990241086935541</aid>
 <cover_pid>7031990241086996817</cover_pid>
 <owner>1637262814</owner>
 <name>Test Album 2 (for work)</name>
 <created>1229460455</created>
 <modified>1229460475</modified>
 <description>this is a test album</description>
 <location/>
 <link>http://www.example.com/album.php?aid=4547&amp;id=1637262814</link>
 <size>1</size>
 <visible>everyone</visible>
 </album>
<album>
 <aid>7031990241086935537</aid>
 <cover_pid>7031990241086996795</cover_pid>
 <owner>1637262814</owner>
 <name>Test Album (for work)</name>
 <created>1229459168</created>
 <modified>1229459185</modified>
 <description>Testing for work</description>
 <location/>
 <link>http://www.example.com/album.php?aid=4493&amp;id=1637262814</link>
 <size>1</size>
 <visible>friends</visible>
 </album>
 </photos_GetAlbums_response>";
    static void Main()
    {
        XmlSerializer ser = new XmlSerializer(typeof(GetAlbumsResponse));
        GetAlbumsResponse response;
        using (StringReader reader = new StringReader(xml))
        {
            response = (GetAlbumsResponse)ser.Deserialize(reader);
        }

    }
}

[Serializable, XmlRoot("photos_GetAlbums_response")]
public class GetAlbumsResponse
{
    [XmlElement("album")]
    public List<Album> Albums {get;set;}

    [XmlAttribute("list")]
    public bool IsList { get; set; }
}
public enum AlbumVisibility
{
    [XmlEnum("")]
    None,
    [XmlEnum("friends")]
    Friends,
    [XmlEnum("friends-of-friends")]
    FriendsOfFriends,
    [XmlEnum("everyone")]
    Everyone

}
[Serializable]
public class Album
{
    static readonly DateTime epoch = new DateTime(1970, 1, 1);
    static long SerializeDateTime(DateTime value)
    {
        return (long)((value - epoch).TotalSeconds);
    }
    static DateTime DeserializeDateTime(long value)
    {
        return epoch.AddSeconds(value);
    }
    [XmlElement("aid")]
    public long AlbumID { get; set; }

    [XmlElement("cover_pid")]
    public long CoverPhotoID { get; set; }

    [XmlElement("owner")]
    public long Owner { get; set; }

    [XmlElement("name")]
    public string AlbumName { get; set; }

    [XmlIgnore]
    public DateTime CreateDate { get; set; }

    [XmlElement("created"), Browsable(false)]
    [EditorBrowsable(EditorBrowsableState.Never)]
    public long CreateDateInt64 {
        get {return SerializeDateTime(CreateDate);}
        set {CreateDate = DeserializeDateTime(value);}
    }

    [XmlIgnore]
    public DateTime LastModifiedDate { get; set; }

    [XmlElement("modified"), Browsable(false)]
    [EditorBrowsable(EditorBrowsableState.Never)]
    public long LastModifiedDateInt64
    {
        get { return SerializeDateTime(LastModifiedDate); }
        set { LastModifiedDate = DeserializeDateTime(value); }
    }

    [XmlElement("description")]
    public string Description { get; set; }

    [XmlElement("location")]
    public string Location { get; set; }

    [XmlElement("link")]
    public string Link { get; set; }

    [XmlElement("size")]
    public int Size { get; set; }

    [XmlElement("visible")]
    public AlbumVisibility Visibility { get; set; }
}



回答3:


(08 Feb) First, treating xml as a string (for reading) isn't going to cause errors.

The problem is the namespace (the xmlns without the xsi); this wasn't in the earlier xml, so I couldn't include it... basically, you need to tell the serializer about it:

[Serializable, XmlRoot("photos_GetAlbums_response",
    Namespace="http://api.example.com/1.0/")]
public class GetAlbumsResponse { /* code as before */ }

[Serializable, XmlType(Namespace="http://api.example.com/1.0/")]
public class Album { /* code as before */ }

On this occasion, a constant for the namespace would make sense (since you are re-using it).

If the xml you are showing is accurate, then the links are still corrupt, though... but maybe this is just copy/paste (i.e. don't apply this change until you know it errors...): you need &amp; (not &). Suggest some "Replace"... at the crudest level:

string fixedXml = xml.Replace("&", "&amp;");

(although something more precise might be better - perhaps a regex)

Note that with the different data I also had to make some of the data strings (rather than long):

[XmlElement("aid")]
public string AlbumID { get; set; }

[XmlElement("cover_pid")]
public string CoverPhotoID { get; set; }

[XmlElement("owner")]
public string Owner { get; set; }

With these changes (and mostly my original code) it works.

Of course, by this point you should be thinking "I wish I'd used xsd".




回答4:


Yes - album is definitely not the root node in your XML.

What I would recommend you do is create a GetAlbumsResponse class which contains a list of albums, and move your deserialize code to the wrapper class.

Basically, remove the root element from your Album class definition, and :

  [XmlRoot (ElementName="GetAlbums_response")]
public class GetAlbumsResponse
{
    #region Constructors

    public GetAlbumsResponse()
    {

    }

    #endregion



    [XmlArray(ElementName="album")]
    public List<Album> Albums{get;set;}

    ... deserialization code...

}




回答5:


Well,

there is a link from Microsoft targeting your problem




回答6:


The Xml that would work for your current code is something like this:

<Album><photos_GetAlbums_response>
<Album>
   <photos_GetAlbums_response>
      <Album>
         <photos_GetAlbums_response> ....

A response, which has an array of Albums, where each Album has a response which is an Array of Albums...etc.

Anyway, I already helped you in your other question, and even went to the trouble of creating a full working code sample. Why did you create another question for the same problem ?




回答7:


Use System.Xml.XmlDocument to parse the input. It shouldn't take more than an hour to write the code to extract the data yourself.




回答8:


Ok - I coded up an example. I took a look at the Facebook API, now here is a FULL working example. Try this:

[XmlRoot("photos_getAlbums_response", Namespace="http://api.facebook.com/1.0/")]
public class GetAlbumsResponse
{
    public GetAlbumsResponse() 
    {    
    }

    [XmlElement("album")]
    public List<Album> Albums { get; set; }
}

public class Album
{
    [XmlElement("aid")]
    public long Aid{get;set;}

    [XmlElement("cover_pid")]
    public long CoverPid{get;set;}

    [XmlElement("owner")]
    public long Owner{get;set;}

    [XmlElement("name")]
    public string Name{get;set;}

    [XmlElement("created")]
    public long Created{get;set;}

    [XmlElement("modified")]
    public long Modified{get;set;}

    [XmlElement("description")]
    public string Description{get;set;}

    [XmlElement("location")]
    public string Location{get;set;}

    [XmlElement("link")]
    public string Link{get;set;}

    [XmlElement("size")]
    public int Size{get;set;}

    [XmlElement("visible")]
    public string Visible{get;set;}

    public Album()
    {}
}

class XmlUtils
{
    public static T DeserializeFromXml<T>(string xml)
    {
        T result;
        XmlSerializer ser = new XmlSerializer(typeof(T));
        using (TextReader tr = new StringReader(xml))
        {
            result = (T)ser.Deserialize(tr);
        }
        return result;
    }
}

Now.. with an xml photos_getAlbums_response from the Facebook API,

You can deserialize like this:

 GetAlbumsResponse response = XmlUtils.DeserializeFromXml<GetAlbumsResponse>(xmlResponseString);



回答9:


This is a really old thread but I just faced the same issue my self while tried to serialize two different list types in the same class under the same XmlArray name, something like

    <Root>
       <ArrayNode>
         <SubnodeType1>...</SubnodeType1>
         <SubnodeType1>...</SubnodeType1>
       </ArrayNode>
    </Root>
Or
    <Root>
       <ArrayNode>
         <SubnodeType2>...</SubnodeType2>
         <SubnodeType2>...</SubnodeType2>
       </ArrayNode>
    </Root>

What has worked for me was to use a class decoration like:

[XmlRoot(Namespace = "", ElementName = "Root")]
public class Root
{
    [XmlArray(ElementName = "ArrayNode", Namespace = "", IsNullable = false, Order = 1)]
    [XmlArrayItem("SubnodeType1")]
    public List<SubnodeType1> SubnodeType1 { get; set; }
    [XmlArray(ElementName = "ArrayNode", Namespace = "", IsNullable = false, Order = 2)]
    [XmlArrayItem("SubnodeType2")]
    public List<SubnodeType2> SubnodeType2 { get; set; }
}

Hope it help someone else :)



来源：https://stackoverflow.com/questions/523245/deserialization-error-the-xml-element-name-from-namespace-is-already-prese

标签
c#
xml
serialization
xml-serialization
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