[resolved] updating an xml dataset - not working?

[jpritchard]

hi,

I have an app i wrote, it involves a list of data that is sourced from an xml structure - its horrible for the user to use as the list keeps reordering while they use it - this is down to the way i have coded it!!

I have problems updating a .net dataset - I cannot updata fields within and have to delete the whole line and re-add it with a new one - seems hardwork just to update a field value!

eg

DataRow obj_newrow  = cur_dataset.Tables["configset"].NewRow();
obj_newrow[0]  = cur_dataset.Tables["configset"].Rows[int_tab_count].ItemArray[0].ToString();
 
cur_dataset.Tables["configset"].Rows.InsertAt(obj_newrow,int_tab_count);
cur_dataset.Tables["configset"].Rows.RemoveAt((int_tab_count+1));

I cannot see why this is - I cannot make the following demo code work - the "after" message returns "fieldvalue1"

test.xml =
 
<?xml version="1.0" standalone="yes"?>
<testxml>
  <configset>
    <field1>fieldvalue1</field1>
    <field2>fieldvalue2</field2>
    <field3>fieldvalue2</field3>
  </configset>
</testxml>
 
 
---
 
System.Data.DataSet cur_dataset = new DataSet();
cur_dataset.ReadXml("C:\\test.xml");
 
MessageBox.Show("before=" + cur_dataset.Tables["configset"].Rows[0].ItemArray[0].ToString());
 
cur_dataset.Tables["configset"].Rows[0].ItemArray[0] = "newvalue";
 
MessageBox.Show("after=" + cur_dataset.Tables["configset"].Rows[0].ItemArray[0].ToString());

I have also tried adding:-

cur_dataset.Tables["configset"].Rows[0].AcceptChanges();
cur_dataset.Tables["configset"].AcceptChanges();
cur_dataset.AcceptChanges();

I cannot get set row0, field0 to "newvalue" other than copying the whole record into a new datarow and doing the insertatr/removeat

is this correct or am i doing something wrong,

many thanks for any comments,
cheers AJP

ps - ms's site seems to say this is do-able - see http://msdn.microsoft.com/library/de...sindataset.asp

[jmcilhinney]

The ItemArray property is supposed to be used to get and set ALL the values in a row in one go. The way you are doing it, you get the array of field values and change one of the values in the array, but then you don't pass the updated array back to the ItemArray property. If you wanted to use the ItemArray property you would have to do it like this:

object[] myArray = cur_dataset.Tables["configset"].Rows[0].ItemArray;

myArray[0] = "newvalue";
cur_dataset.Tables["configset"].Rows[0].ItemArray = myArray;

There is no point to using the ItemArray property in this situation though. Just set the field value directly:

cur_dataset.Tables["configset"].Rows[0][0] = "newvalue";

[jpritchard]

hi,

thankyou - I thought i was doing something stupid!.

I can now remove a load of removeat/insertat statements within my program.
I had spent most of yesterday morning wondering what i was actually doing wrong before I asked here!.

much appreciated for your help again - thankyou,

cheers AJP