Issue reading XML file into C# DataSet

Question

I was given an .xml file that I needed to read into my code as a DataSet (as background, the file was created by creating a DataSet in C# and calling dataSet.WriteXml(file, XmlWriteMode.IgnoreSchema), but this was done by someone else).

The .xml file was shaped like this:

 <?xml version="1.0" standalone="yes"?>
 <NewDataSet>
  <Foo>
    <Bar>abcd</Bar>
    <Foo>efg</Foo>
  </Foo>
  <Foo>
    <Bar>hijk</Bar>
    <Foo>lmn</Foo>
  </Foo>
</NewDataSet>

Using C# and .NET 2.0, I read the file in using the code below:

        DataSet ds = new DataSet();
        ds.ReadXml(file);

Using a breakpoint, after this line ds.Tables[0] looked like this (using dashes in place of underscores that I couldn't get to format properly):

Bar     Foo-Id    Foo-Id-0
abcd     0         null
null     1         0
hijk     2         null
null     3         2

I have found a workaround (I know there are many) and have been able to successfully read in the .xml, but what I would like to understand why ds.ReadXml(file) performed in this manner, so I will be able to avoid the issue in the future. Thanks.

Answer 1

This appears to be correct for your nested Foo tags:

<NewDataSet>  
  <Foo>              <!-- Foo-Id: 0 -->
    <Bar>abcd</Bar>
    <Foo>efg</Foo>   <!-- Foo-Id: 1, Parent-Id: 0 -->
  </Foo>
  <Foo>              <!-- Foo-Id: 2 -->
    <Bar>hijk</Bar>
    <Foo>lmn</Foo>   <!-- Foo-Id: 3, Parent-Id: 2 -->
  </Foo>
</NewDataSet>

So this correctly becomes 4 records in your result, with a parent-child key of "Foo-Id-0"

Try:

<NewDataSet>  
  <Rec>              <!-- Rec-Id: 0 -->
    <Bar>abcd</Bar>
    <Foo>efg</Foo>   
  </Rec>
  <Rec>              <!-- Rec-Id: 1 -->
    <Bar>hijk</Bar>
    <Foo>lmn</Foo>   
  </Rec>
</NewDataSet>

Which should result in:

Bar     Foo        Rec-Id
abcd    efg        0
hijk    lmn        1