After writing and reading an xml string to and from a stream, it ceases to be deserializable. The new string is clipped.
string XmlContent = getContentFromMyDataBase();
XmlSerializer xs = new XmlSerializer(typeof(MyObj));
MemoryStream ms = new MemoryStream();
StreamWriter sw = new StreamWriter(ms);
char[] ca = XmlContent.ToCharArray(); // still working up to this point.
ms.Position = 0;
sw.Write(ca);
StreamReader sr = new StreamReader(ms);
ms.Position = 0;
string XmlContentAgain = sr.ReadToEnd();
Console.WriteLine(XmlContentAgain); // (outputstring is too short.)
MyObj theObj = (MyObj)xs.Deserialize(ms); // Can't deserialize.
Any suggestions as to how to fix this or what is causing the problem? My only guess is that there is some form of encoding issue, but I wouldn't know how to go about finding/fixing it.
Additionally, myObj has a generic dictionary member, which typically isn't serializable, so I have stolen code from Paul Welter in order to serialize it.
Try flushing and disposing or even better simplify your code using a StringReader:
string xmlContent = getContentFromMyDataBase();
var xs = new XmlSerializer(typeof(MyObj));
using (var reader = new StringReader(xmlContent))
{
var theObj = (MyObj)xs.Deserialize(reader);
}
Note: The getContentFromMyDataBase method also suggests that you are storing XML in your database that you are deserializing back to an object. Don't.
You need to Flush or Close (closing implicitly flushes) the StreamWriter, or you cannot be sure it is done writing to the underlying stream. This is because it is doing some internal buffering.
Try this:
using(StreamWriter sw = new StreamWriter(ms))
{
char[] ca = XmlContent.ToCharArray(); // still working up to this point.
ms.Position = 0;
sw.Write(ca);
}
StreamReader sr = new StreamReader(ms);
ms.Position = 0;
string XmlContentAgain = sr.ReadToEnd();
Related
I am trying to serialize a simple object (5 string properties) into XML to save to a DB Image field. Then I need to DeSerialize it back into a string later in the program.
However, I am getting some errors - caused by the XML being saved thinking it is in UTF-16 - however, when I load it from the DB back into a string - it thinks it is a UTF 8 String.
The error I get is
InnerException {"There is no Unicode byte order mark. Cannot switch to Unicode."} System.Exception {System.Xml.XmlException}
-- Message "There is an error in XML document (0, 0)." string
Is this happening because of the two different ways I save and load the string to/from the DB? On the save I am using a StringBuilder - but on the load from DB I am using just a String.
Thoughts?
Serialize and Save to DB
// Now Save the OBject XML to the Query Tables
var serializer = new XmlSerializer(ExportConfig.GetType());
StringBuilder StringResult = new StringBuilder();
using (var writer = XmlWriter.Create(StringResult))
{
serializer.Serialize(writer, ExportConfig);
}
//MessageBox.Show("XML : " + StringResult);
// Now Save to the Query
try
{
string UpdateSQL = "Update ZQryRpt "
+ " Set ExportConfig = " + TAGlobal.QuotedStr(StringResult.ToString())
+ " where QryId = " + TAGlobal.QuotedStr(((DataRowView)bindingSource_zQryRpt.Current).Row["QryID"].ToString())
;
ExecNonSelectSQL(UpdateSQL, uniConnection_Config);
}
catch (Exception Error)
{
MessageBox.Show("Error Setting ExportConfig: " + Error.Message);
}
Load from DB And Deserialize
byte[] binaryData = (byte[])((DataRowView)bindingSource_zQryRpt.Current).Row["ExportConfig"];
string XMLStored = System.Text.Encoding.UTF8.GetString(binaryData, 0, binaryData.Length);
if (XMLStored.Length > 0)
{
IIDExportObject ExportConfig = new IIDExportObject();
var serializer = new XmlSerializer(ExportConfig.GetType());
//StringBuilder StringResult = new StringBuilder(XMLStored);
// Load the XML from the Query into the StringBuilder
// Now we need to build a Stream from the String to use in the XMLReader
byte[] byteArray = Encoding.UTF8.GetBytes(XMLStored);
MemoryStream stream = new MemoryStream(byteArray);
using (var reader = XmlReader.Create(stream))
{
ExportConfig = (IIDExportObject)serializer.Deserialize(reader);
}
}
John - thank you very much for the comment! It allowed me to complete the code and find a solution.
As you noted - using a stream reader was the solution - but I could not read the first line because there was only one 'line' in my string. However, I could use the line
using (StreamReader sr = new StreamReader(stream, false))
Which allows me to read the stream and ignore the "Byte Order Mark Detection" set to false.
string XMLStored = MainFormRef.GetExportConfigForCurrentQuery();
if (XMLStored.Length > 0)
{
IIDExportObject ExportConfig = new IIDExportObject();
try
{
var serializer = new XmlSerializer(ExportConfig.GetType());
// Now we need to build a Stream from the String to use in the XMLReader
byte[] byteArray = Encoding.UTF8.GetBytes(XMLStored);
MemoryStream stream = new MemoryStream(byteArray);
// Now we need to use a StreamReader to get around UTF8 vs UTF16 issues
// A little cumbersome - but it works
using (StreamReader sr = new StreamReader(stream, false))
{
using (var reader = XmlReader.Create(sr))
{
ExportConfig = (IIDExportObject)serializer.Deserialize(reader);
}
}
}
catch
{
}
I am not sure this is the best solution - but it works. I will be curious to see if anyone else has a better way of dealing with this.
Thanks to G Bradley, I took his answer and generalized it a bit to make it a bit easier to call.
public static string SerializeToXmlString<T>(T objectToSerialize)
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
XmlWriterSettings settings = new XmlWriterSettings();
settings.Indent = false;
settings.Encoding = Encoding.UTF8;
StringBuilder builder = new StringBuilder();
using (XmlWriter writer = XmlWriter.Create(builder, settings))
{
serializer.Serialize(writer, objectToSerialize);
}
return builder.ToString();
}
public static T DeserializeFromXmlString<T>(string xmlString)
{
if (string.IsNullOrWhiteSpace(xmlString))
return default;
var serializer = new XmlSerializer(typeof(T));
byte[] byteArray = Encoding.UTF8.GetBytes(xmlString);
MemoryStream stream = new MemoryStream(byteArray);
using (StreamReader sr = new StreamReader(stream, false))
{
using (var reader = XmlReader.Create(sr))
{
return (T)serializer.Deserialize(reader);
}
}
}
I'm writing a web service in .NET C# that takes in an object, converts it to xml, applies an XSLT template, runs the transformation, and returns an MS work file.
Here is the code for the function:
public static HttpResponseMessage Transform(object data)
{
var response = new HttpResponseMessage(HttpStatusCode.OK);
StringWriter stringWriter = new StringWriter();
XmlWriter xmlWriter = XmlWriter.Create(stringWriter);
var applicationDirectory = AppDomain.CurrentDomain.BaseDirectory;
var xsltPath = applicationDirectory + #"\Reporting\Files\Template.xslt";
var templatePath = applicationDirectory + #"\Reporting\Files\Template.docx";
var xmlObject = new System.Xml.Serialization.XmlSerializer(data.GetType());
MemoryStream stream;
using (stream = new MemoryStream())
{
var sw = new StreamWriter(stream);
xmlObject.Serialize(stream, data);
stream.Position = 0;
XslCompiledTransform transform = new XslCompiledTransform();
transform.Load(xsltPath);
using (XmlReader xmlReader = XmlReader.Create(stream))
{
transform.Transform(xmlReader, xmlWriter);
XmlDocument newWordContent = new XmlDocument();
newWordContent.LoadXml(stringWriter.ToString());
var outputPath = applicationDirectory + #"\Reporting\Temp\temp.docx";
System.IO.File.Copy(templatePath, outputPath, true);
using (WordprocessingDocument output = WordprocessingDocument.Open(outputPath, true))
{
Body updatedBodyContent = new Body(newWordContent.DocumentElement.InnerXml);
output.MainDocumentPart.Document.Body = updatedBodyContent;
output.MainDocumentPart.Document.Save();
}
response.Content = new StreamContent(new FileStream(outputPath, FileMode.Open, FileAccess.Read));
response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
response.Content.Headers.ContentDisposition.FileName = outputPath;
}
}
return response;
}
When I make a request, it gives me a word file without the data.
I put a breakpoint at using (XmlReader xmlReader = XmlReader.Create(stream)).
After running that line, xmlReader has a value of {None}.
I'm also trying to avoid creating an XML file for efficiency(Hence MemoryStream).
Any idea why this isn't working? And is there a better way of accomplishing this?
Thanks,
Gerson
What happens if you change this:
Body updatedBodyContent = new Body(newWordContent.DocumentElement.InnerXml);
to this:
Body updatedBodyContent = new Body(newWordContent.InnerXml);
or this:
Body updatedBodyContent = new Body(newWordContent.DocumentElement.OuterXml);
The way you have it there would cause the outer element of the transformed XML to be omitted, and I doubt that's what you want (though can't say for sure because you've shown us neither the input XML or the XSLT.
Given the following code snippet:
try
{
var myTxt = "";
var serializer = new DataContractSerializer(myObject.GetType());
var memoryStream = new MemoryStream()
serializer.WriteObject(memoryStream, myObject);
memoryStream.Position = 0;
using (var reader = new StreamReader(memoryStream))
{
myTxt = reader.ReadToEnd();
}
.
.
.
}
catch (IOException ioEx)
{
//log or whatever...
throw;
}
Typically I'd have a using statement around my memory stream,
but from my understanding disposing the StreamReader will close the Memory Stream.
So the question is, is there anything REALLY wrong with the above?
You could simplify your code as I don't see the point of writing, rewinding and reading:
var serializer = new DataContractSerializer(facets.GetType());
using (var stream = new MemoryStream())
{
serializer.WriteObject(stream, facets);
string xml = Encoding.UTF8.GetString(stream.ToArray());
}
I think its fine because MemoryStream doesn't hold unmanaged resources anyway, but if you wanted to be extra safe you could do this:
var memoryStream = new MemoryStream()
StreamReader reader = null;
try{
serializer.WriteObject(memoryStream, myObject);
memoryStream.Position = 0;
reader = new StreamReader(memoryStream)
//...
}
finally
{
if(reader != null)
reader.Dispose();
else
memoryStream.Dispose();
}
It is a good practice to use either
using (var stream = new MemoryStream(...))
using (var reader = new StreamReader(stream))
{
myTxt = reader.ReadToEnd();
}
Here both stream and reader will be disposed by runtime
or Close() manually both reader(writer) and stream
To test your scenario, I've added
memoryStream.Seek(0, SeekOrigin.Begin);
to the end and received an System.ObjectDisposedException, your code seems valid.
Of course vcsjones's comment is also valid.
BinaryFormatter formatter = new BinaryFormatter();
using (MemoryStream m = new MemoryStream())
{
formatter.Serialize(m, list);
StreamReader sr = new StreamReader(m);
HiddenField1.Value = sr.ReadToEnd();
}
i'm getting a blank value for HiddenField1.Value. Not sure what I'm doing is even possible? list is definitely populated (is a List<T>)
Depending on what you want to achieve... One option is to show content of the binary stream as Base64 string:
var memoryStream = new MemoryStream();
using(memoryStream)
{
formatter.Serialize(memoryStream, list);
}
HiddenField1.Value = Convert.ToBase64String(memoryStream.ToArray());
Change it to:
BinaryFormatter formatter = new BinaryFormatter();
using (MemoryStream m = new MemoryStream())
{
formatter.Serialize(m, list);
m.Position = 0;
StreamReader sr = new StreamReader(m);
HiddenField1.Value = sr.ReadToEnd();
}
You need to reset the position of the stream back to the beginning before reading it. Also, you shouldn't use StreamReader to convert a binary stream like this to text, because it will break in unexpected ways. If you want the results in a text-like format, use Convert.ToBase64String as in #Alexei's answer.
Right now I'm using XmlTextWriter to convert a MemoryStream object into string. But I wan't to know whether there is a faster method to serialize a memorystream to string.
I follow the code given here for serialization - http://www.eggheadcafe.com/articles/system.xml.xmlserialization.asp
Edited
Stream to String
ms.Position = 0;
using (StreamReader sr = new StreamReader(ms))
{
string content = sr.ReadToEnd();
SaveInDB(ms);
}
String to Stream
string content = GetFromContentDB();
byte[] byteArray = Encoding.ASCII.GetBytes(content);
MemoryStream ms = new MemoryStream(byteArray);
byte[] outBuf = ms.GetBuffer(); //error here
using(MemoryStream stream = new MemoryStream()) {
stream.Position = 0;
var sr = new StreamReader(stream);
string myStr = sr.ReadToEnd();
}
You cant use GetBuffer when you use MemoryStream(byte[]) constructor.
MSDN quote:
This constructor does not expose the
underlying stream. GetBuffer throws
UnauthorizedAccessException.
You must use this constructor and set publiclyVisible = true in order to use GetBuffer
In VB.net i used this
Dim TempText = System.Text.Encoding.UTF8.GetString(TempMemoryStream.ToArray())
in C# may apply