DataSet.GetXml not returning null results

Question

Hi, whenever I convert a DatSet into an XML with DataSet.GetXml, any null value is ignored, so, where i expect this:

<value1>a</value1>
<value2></value2>
<value3>c</value3>

I get this instead:

<value1>a</value1>
<value3>c</value3>

Any quick and dirty way to handle this? Thanks

EDIT: I think a solution would be using WriteXml. Could anyone provide me with a sample of using it WITHOUT writing to a file but getting a string just like GetXml does? Thanks

Answer 1

The problem is listed here in the Microsoft KB article:

http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q317961

The problem is that you have no schema attached to your dataset that specifies that that element should be written out.

I don't believe that using WriteXml will solve the problem, as the documentation states, "Calling this method is identical to calling WriteXml with XmlWriteMode set to IgnoreSchema." but you are free to try - here is the equivalent code:

StringWriter sw = new StringWriter();
ds.WriteXml(sw);
string outputXml = sw.ToString();

Answer 2

Hi Sam, I tried your function and I get the following error at the line row[column] = default(column.DataType);

and the error is: The type or namespace name 'column' could not be found(are you missing a using directive or an assembly reference?)

By the way, I am using VS 2008 and C#. I would appreciate your response in this regrrd. You can respond to [email protected]

Thanks Pankaja

Answer 3

I've edited this, from my previous answer.

I believe that's a limitation on how DataSet exports its data to XML. Even specifying the WriteMode to write the schema, the resulting XML still lacks elements when their values are null.

StringWriter sw = new StringWriter();
ds.WriteXml(sw, XmlWriteMode.WriteSchema);

If you can avoid having null values in your DataSet, replacing them for string.Empty or any other default value, the corresponding elements will be present:

<value1>a</value1>
<value2 />
<value3>c</value3>