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From: Family Tree Mike on 26 Nov 2009 10:17
Rob W wrote:
> I have amended my LINQ however I'm still not able to retrieve the datarow
> values as string though using the .Tostring conversion.
>
> Anyone got any ideas how to extract the xml data from the datatable using
> LINQ?
>
> Dim quotes = From quote In
> frmMainQuote.quoteData.Tables("quote").AsEnumerable _
>
> Where quote.Item("category").ToString = cboCategory.SelectedItem.ToString _
>
> And quote.Item("author").ToString = txtAuthor.Text _
>
> And quote.Item("text").ToString Like "*" & txtKeyword.Text & "*" _
>
> And quote.Item("date").ToString = dtpQuoteDate.Value.ToString("dd MMMM
> yyyy") _
>
> Select stringQuote = quote.ToString()
>
>
>
>
>
>
>
> "Rob W" <robwha(a)o2.co.uk> wrote in message
> news:OtD4BDibKHA.1640(a)TK2MSFTNGP06.phx.gbl...
>> Greetings,
>>
>> For no shortage of trying I am unable to convert the contents of a datarow
>> (containing xml data) to type string, using .tostring results in
>> conversion errors in the linq and when adding
>> adding as an xml element to an xmldocument the literal words systems.data
>> (see code below for examples).
>>
>> Is it possible from the linq to extract the datatable rows containg xml
>> and then write them to an xmldocument as xmlelements?
>>
>>
>> LINQ Code:-
>>
>> Dim quotes = From quote In
>> frmMainQuote.quoteData.Tables("quote").AsEnumerable _
>> Select quote _
>>
>> Where (quote.Item("category").ToString =
>> cboCategory.SelectedItem.ToString) _
>>
>> And (quote.Item("author").ToString = txtAuthor.Text) _
>>
>> And (quote.Item("text").ToString Like "*" & txtKeyword.Text & "*") _
>>
>> And (quote.Item("date").ToString = dtpQuoteDate.Value.ToString("dd MMMM
>> yyyy"))
>>
>>
>>
>> 'WRITE OUT xmlElement to an xmlDocument:-
>>
>> Dim outQuoteDoc As New XDocument(New XElement("quotefile", quotes))
>>
>> 'Or
>>
>> Dim outQuoteDoc As New XDocument(New XElement("quotefile",
>> quotes.tostring))
>>
>>
>>
>> Thanks
>>
>> Rob
>>
>>
>
>

Have you looked at the string you get from converting 'quotes' using
'ToString()'? It should be something like
'System.Data.EnumerableRowCollection`1[System.Data.DataRow]', which
isn't the xml you want, I suspect.

Which Column has the xmldata?

--
Mike
From: Family Tree Mike on 26 Nov 2009 11:20
Rob W wrote:
> Thanks for the reply.
>
> Indeed it does read
> 'System.Data.EnumerableRowCollection`1[System.Data.DataRow]' when written
> out to the xml document.
>
>
> The datatable is intially populated via :-
> Dim xmlquotesfile As New XmlDataDocument()
>
> xmlquotesfile.DataSet.ReadXml("file.xml")
>
> cQuoteDataSet = xmlquotesfile.DataSet
>
>
>
> So the datatable is based on xml data, It's a mystery to me really how the
> data actually looks with the datatable.
>
> In a for each Loop within the datatable and print out the individual
> datarow columns it displays the text values inside the element tags and
> never see the xml tags.
>
> I have used the dataset readxml/write with success for other tasks.
> Can I query the datatable written from an xml document and get xml output I
> wonder via LINQ?
>
> Thanks
> Rob
>

Rob,

The datatable is more or less, just a set of rows and columns whether it
comes from Xml, SQL, MySQL, or SomeStrangeDbEngine... If you want to
get xml for the query, you still need to convert the data to an xml file
by using WriteXml(). If you want to write each row as if it was xml,
then you would need to create a custom output creating strings that look
like xml. I'm not really sure I understand why you would want to do
that though.

As an alternative, you could keep everthing as an XmlDocument and use
Linq to Xml. Have a look at
http://www.hookedonlinq.com/LINQtoXML5MinuteOverview.ashx for some
examples.

--
Mike
From: Family Tree Mike on 26 Nov 2009 12:09
Rob W wrote:
> Thanks Mike for the reply.
>
> The requirement is to create an xml file based on search criteria based on
> the form input.
>
> I do have working code with a file but I thought it would be more efficient
> to use a dataset rather than reload a file, experimenting really.
>
> I
> copied the original table structure and then added rows from the LINQ
> result and wrote to an xml file
> Dim dd As New DataSet
>
> dd.Tables.Add(frmMainQuote.quoteData.Tables("quote").Clone)
>
> For Each ee In quotes
>
> dd.Tables("quote").ImportRow(ee)
>
> Next
>
> dd.WriteXml("name.xml")
>
>
> I now have a valid xmlfile :-)
>
> The only downside is the root element is specified as <NewDataSet> can this
> be changed?
> Otherwise my schema is not going to be happy :-(
>
> <?xml version="1.0" standalone="yes"?>
> <NewDataSet>
> <quote>
> <date>25 November 2009</date>
> <author>da</author>
> <category>Careers</category>
> <text>da</text>
> </quote>
> <quote>
> <date>25 November 2009</date>
> <author>da</author>
> <category>Careers</category>
> <text>dada</text>
> </quote>
> </NewDataSet>
>
> Thanks for all the help
> Rob
>
>

To change the document element in the output, change the DataSetName
property of the resulting dataset (dd.DataSetName = "MyDataset").

--
Mike
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