Xml with Namespace but without xmlns

Question

I am working on a program in C# that edits open-document files on xml level. For example it adds rows to tables.

So I load the content.xml into an XmlDocument "doc" and traverse the xml structure. Say I have the <table:table-row> node in an XmlNode "row" and now I want to add a <table:table-cell> node to it. So I call

XmlDocument doc = new XmlDocument();
doc.Load(filename);
...
XmlNode row = ...;
...
XmlNode cell = doc.CreateElement("table:table-cell");
row.Append(cell);
...
doc.Save(filename);

The problem is that, in the file, the new node only contains <table-cell>...</table-cell>

C# just decides to ignore what I told it to and does something else without even telling me (at first I overlooked the problem and was wondering why it didn't work although the generated xml looked okay).

From what I gathered out so far, the problem has to do with the fact that "table:" is a namespace. When I also supply a NamespaceURI to CreateElement, I get <table:table-cell table:xmlns="THE_URI" >... - but the original document did not have this xmlns, so I don't want it either...

I tried to use an XmlTextWriter and setting writer.Settings.Namespaces = false, because I thought, this should suppress the output of the xmlns, but it only caused an exception - the document has some namespaces, which are forbidden if Namespaces is set to false... (wtf!? suppressing the output of xmlns seems a billion times more logical than throwing an exception if an xmlns is present...)

In some similar discussions I read that you should set the cell.Name manually, but this property is read-only... Others suggest to change it on text-file level (that's tinkering and it would be slow)

Can anyone give me a hint?

Answer 1

Every namespace should have at least one xmlns definition with a URI. This is the ultimate differentiation between two tags.

You can however have the xmlns attribute declared only once in the file (in the beginning).

See Creating a specific XML document using namespaces in C#

Answer 2

The table: parts are not namespaces. They are "namespace prefixes". They are an alias for the actual namespace. They must be declared somewhere. If they are not declared at all in your source XML, then it is not valid XML, and you shouldn't expect to be able to process it.

Are you sure that what you have loaded is the entire XML document? They haven't left off parts to make it simpler? Those parts may be the ones that contain the definition of table: .