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XmlDocument.Load using MemoryStream...save me... I have some code that builds an Xml file and dumps it on my drive. It works. Now, I want to do the same thing, but skip the file and just hold the XmlDocument in memory and pass it around to various methods. Essentially, my code is this: ----------------------------- XmlDocument myXmlDocument = new XmlDocument(); MemoryStream myStream = new MemoryStream(); XmlTextWriter myWriter = new XmlTextWriter(myStream, Encoding.UTF8); // Code to build the XmlDocument using myWriter myWriter.WriteStartDocument(); myWriter.WriteStartElement(... // continue building the XmlDocument using myWriter myWriter.WriteEndDocument(); myXmlDocument.Load(myStream); myWriter.Flush(); myWriter.Close(); return myXmlDocument; --------------------- The exception occurs on the "myXmlDocument.Load(myStream) line...System.Xml.XmlException: The root element is missing... Anyone help me out? Thanks in advance. You will need to change the read/write position of the Stream. As you write
data to a Stream the current location pointer moves. This pointer is used for both read and write operations so when you try to perform the Load() it reads in nothing (because the read location is at the end of the Stream from the last write command.) To change the current read/write location you can do the following right before the xmlDocument.Load() call: myStream.Seek(0, System.IO.SeekOrigin.Begin); This will move the read/write location back to the start of the Stream and allow the XMLDocument to read in the entire contents. Keep in mind however that if you want to write more data to the Stream you will need to move the read/write pointer back to the end of the stream with the same command (just different parameters.) Hope this helps! Show quote "memyselfandI" <memyselfa***@discussions.microsoft.com> wrote in message news:FAAD9665-E0A5-495E-8A6E-A6124C11DE7C@microsoft.com... > Hello. Not very experienced using Streams of any kind, and Google didn't > save me... > > I have some code that builds an Xml file and dumps it on my drive. It > works. Now, I want to do the same thing, but skip the file and just hold > the > XmlDocument in memory and pass it around to various methods. Essentially, > my > code is this: > > ----------------------------- > > XmlDocument myXmlDocument = new XmlDocument(); > MemoryStream myStream = new MemoryStream(); > XmlTextWriter myWriter = new XmlTextWriter(myStream, Encoding.UTF8); > > // Code to build the XmlDocument using myWriter > myWriter.WriteStartDocument(); > myWriter.WriteStartElement(... > > // continue building the XmlDocument using myWriter > > myWriter.WriteEndDocument(); > myXmlDocument.Load(myStream); > myWriter.Flush(); > myWriter.Close(); > > return myXmlDocument; > > --------------------- > > The exception occurs on the "myXmlDocument.Load(myStream) > line...System.Xml.XmlException: The root element is missing... > > Anyone help me out? Thanks in advance. > Sorry, no go. Same error. I've noticed that the Length and Position of
myStream are always 0. I am forced to conclude that the myXmlTextWriter is not writing to the MemoryStream. Unfortunately, I have no clue why not, and I find that the documentation around this topic is of little help to me.... Any help appreciated. Thanks in advance. I rather obviously am clueless about how to use Streams.... :( Show quote "C.C. (aka Me)" wrote: > You will need to change the read/write position of the Stream. As you write > data to a Stream the current location pointer moves. This pointer is used > for both read and write operations so when you try to perform the Load() it > reads in nothing (because the read location is at the end of the Stream from > the last write command.) > > To change the current read/write location you can do the following right > before the xmlDocument.Load() call: > > myStream.Seek(0, System.IO.SeekOrigin.Begin); > > This will move the read/write location back to the start of the Stream and > allow the XMLDocument to read in the entire contents. Keep in mind however > that if you want to write more data to the Stream you will need to move the > read/write pointer back to the end of the stream with the same command (just > different parameters.) > > Hope this helps! > Here is the code that I am using. I have a simple form with a button and a
text box on it. When I click the button I exectute this code which populates the text box. ++++++++++++++++++++++++++++++++++++++++++++++++++++++ System.Xml.XmlDocument xmlDoc = new System.Xml.XmlDocument(); System.IO.MemoryStream myStream = new System.IO.MemoryStream(); System.Xml.XmlTextWriter myWriter = new System.Xml.XmlTextWriter(myStream, System.Text.Encoding.ASCII); // Code to build the XmlDocument using myWriter myWriter.WriteStartElement("RootNode"); myWriter.WriteStartElement("Node1"); myWriter.WriteString("Node1 Data"); myWriter.WriteEndElement(); myWriter.WriteStartElement("Node2"); myWriter.WriteString("Node2 Data"); myWriter.WriteEndElement(); myWriter.WriteEndElement(); myWriter.Flush(); myStream.Seek(0, System.IO.SeekOrigin.Begin); xmlDoc.Load(myStream); myWriter.Close(); txtXML.Text = xmlDoc.InnerXml; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++= Maybe give it a try and see what happens? It works fine on my system so it should on yours too. -- Show quote~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Charles Cox VC/VB/C# Developer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "memyselfandI" <memyselfa***@discussions.microsoft.com> wrote in message news:5FB0EE3E-51EC-427B-B0F3-FC35C89C6F99@microsoft.com... > Sorry, no go. Same error. I've noticed that the Length and Position of > myStream are always 0. I am forced to conclude that the myXmlTextWriter > is > not writing to the MemoryStream. Unfortunately, I have no clue why not, > and > I find that the documentation around this topic is of little help to > me.... > > Any help appreciated. Thanks in advance. I rather obviously am clueless > about how to use Streams.... :( > > "C.C. (aka Me)" wrote: > >> You will need to change the read/write position of the Stream. As you >> write >> data to a Stream the current location pointer moves. This pointer is used >> for both read and write operations so when you try to perform the Load() >> it >> reads in nothing (because the read location is at the end of the Stream >> from >> the last write command.) >> >> To change the current read/write location you can do the following right >> before the xmlDocument.Load() call: >> >> myStream.Seek(0, System.IO.SeekOrigin.Begin); >> >> This will move the read/write location back to the start of the Stream >> and >> allow the XMLDocument to read in the entire contents. Keep in mind >> however >> that if you want to write more data to the Stream you will need to move >> the >> read/write pointer back to the end of the stream with the same command >> (just >> different parameters.) >> >> Hope this helps! >> > Hey,
Thanks, it worked. The problem was the myWriter.Flush() method. I had it in the wrong place!! I didn't fully understand what it did, I thought it was part of clean up. Needed to do that before the myStream.Seek() and myXmlDocument.Load() method calls. Silly me. While I have you though, could you tell me using the MemoryStream/XmlTextWriter combo to make my XmlDocument is preferable to just building the XmlDocument directly? Or is this just a "more than one way to skin a cat" kinda deal. Thanks again! Show quote "C.C. (aka Me)" wrote: > Here is the code that I am using. I have a simple form with a button and a > text box on it. When I click the button I exectute this code which populates > the text box. > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > System.Xml.XmlDocument xmlDoc = new System.Xml.XmlDocument(); > System.IO.MemoryStream myStream = new System.IO.MemoryStream(); > System.Xml.XmlTextWriter myWriter = new System.Xml.XmlTextWriter(myStream, > System.Text.Encoding.ASCII); > // Code to build the XmlDocument using myWriter > myWriter.WriteStartElement("RootNode"); > myWriter.WriteStartElement("Node1"); > myWriter.WriteString("Node1 Data"); > myWriter.WriteEndElement(); > myWriter.WriteStartElement("Node2"); > myWriter.WriteString("Node2 Data"); > myWriter.WriteEndElement(); > myWriter.WriteEndElement(); > myWriter.Flush(); > myStream.Seek(0, System.IO.SeekOrigin.Begin); > xmlDoc.Load(myStream); > myWriter.Close(); > txtXML.Text = xmlDoc.InnerXml; > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++= > > Maybe give it a try and see what happens? It works fine on my system so it > should on yours too. > > -- > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Charles Cox > VC/VB/C# Developer > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ memyselfandI <memyselfa***@discussions.microsoft.com> wrote:
> Thanks, it worked. The problem was the myWriter.Flush() method. I had it It's not, particularly - unless you're passing the "new" document to a > in the wrong place!! I didn't fully understand what it did, I thought it was > part of clean up. Needed to do that before the myStream.Seek() and > myXmlDocument.Load() method calls. Silly me. > > While I have you though, could you tell me using the > MemoryStream/XmlTextWriter combo to make my XmlDocument is preferable to just > building the XmlDocument directly? Or is this just a "more than one way to > skin a cat" kinda deal. method which might modify it, and you want to keep hold of the original. Even if you *do* want to clone, you should look at calling XmlDocument.CloneNode instead, as it's a lot easier than writing it all out and reading it back in. -- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too There are a ton of ways to create XML and it probably just depends on how
much you want to hand code in terms of the XML. You could just do something like this if you wanted: String xml = ""; XmlDocument xmlDoc = new XmlDocument(); xml = "<RootNode>\r\n"; xml += "<Node1>Node1 value</Node1>\r\n"; xml += "</RootNode>\r\n"; xmlDoc.LoadXml(xml); //Might not be the correct method - I am just typing this from memory. This will create the xml as a string and them shove it into the XmlDocument. If you only have a few items to add then this may be the way to go? Or you could create a method that takes a node name (RootNode, None1, etc.) and a value (Node1 Value) as parameters and it does the above for you. It just depends on what you need to do and how much XML specific stuff you want to deal with. -- Show quote~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Charles Cox VC/VB/C# Developer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "memyselfandI" <memyselfa***@discussions.microsoft.com> wrote in message news:65D52558-6BF4-4E44-85B1-D95CF473C74E@microsoft.com... > Hey, > > Thanks, it worked. The problem was the myWriter.Flush() method. I had it > in the wrong place!! I didn't fully understand what it did, I thought it > was > part of clean up. Needed to do that before the myStream.Seek() and > myXmlDocument.Load() method calls. Silly me. > > While I have you though, could you tell me using the > MemoryStream/XmlTextWriter combo to make my XmlDocument is preferable to > just > building the XmlDocument directly? Or is this just a "more than one way > to > skin a cat" kinda deal. > > Thanks again! > > "C.C. (aka Me)" wrote: > >> Here is the code that I am using. I have a simple form with a button and >> a >> text box on it. When I click the button I exectute this code which >> populates >> the text box. >> >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> System.Xml.XmlDocument xmlDoc = new System.Xml.XmlDocument(); >> System.IO.MemoryStream myStream = new System.IO.MemoryStream(); >> System.Xml.XmlTextWriter myWriter = new >> System.Xml.XmlTextWriter(myStream, >> System.Text.Encoding.ASCII); >> // Code to build the XmlDocument using myWriter >> myWriter.WriteStartElement("RootNode"); >> myWriter.WriteStartElement("Node1"); >> myWriter.WriteString("Node1 Data"); >> myWriter.WriteEndElement(); >> myWriter.WriteStartElement("Node2"); >> myWriter.WriteString("Node2 Data"); >> myWriter.WriteEndElement(); >> myWriter.WriteEndElement(); >> myWriter.Flush(); >> myStream.Seek(0, System.IO.SeekOrigin.Begin); >> xmlDoc.Load(myStream); >> myWriter.Close(); >> txtXML.Text = xmlDoc.InnerXml; >> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++= >> >> Maybe give it a try and see what happens? It works fine on my system so >> it >> should on yours too. >> >> -- >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> Charles Cox >> VC/VB/C# Developer >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >  |
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