asked on

selectsinglenode problem parsing xml in VB.net

Dim path = "......"
Dim xmldoc As New XmlDocument

Try

xmldoc.Load(path)
makeNewDataSet(xmldoc.DocumentElement("resultset"))
Catch ex As Exception
End Try

Then, in the subroutine "makenewdataset", I try to access values use selectsinglenode to grab field nodes by attribute "name"
n is a node representing a record.

Dim xpath = "/field[@name='first']"
Response.Write("--" & n.SelectSingleNode(xpath).InnerText)

This for some reason just shuts down the code. It doesn't throw an error. It just mysteriously breaks a loop.

Carl Tawn

It possibly is throwing an error. The exception will bubble to the calling method, which in your sample has nothing the the exception handler, so it will do nothing.

Can you provide a bit more info ? Maybe the rest of the makeNewDataSet method and a sample of the XML you are using.

alisman

ASKER

you're right. it was throwing an exception.

Object reference not set to an instance of an object.

on this code:

Response.Write("--" & n.SelectSingleNode(xpath).InnerText)

why would it do that?

YZlat

n.SelectSingleNode(xpath) might be Nothing

YZlat

try replacing

Response.Write("--" & n.SelectSingleNode(xpath).InnerText)

with this

Dim node as XmlNode=n.SelectSingleNode(xpath)
If Not node Is Nothing Then
Response.Write("--" & node.InnerText)
End if

Carl Tawn

As YZlat says, its probably not finding the node.

We'd need to see a sample of the XML to see why you're not getting anything.

alisman

ASKER

here's the xml. i just gave you the xml down to relevant node, which is record. it is valid. please ignore the dashes at the beginning of nodes. those are from ieexplorer. you'll see that records are childnodes of resultset. i am passing the resultset node to the madedataset function. thanks to all.

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<!DOCTYPE fmresultset (View Source for full doctype...)>
- <fmresultset xmlns="http://www.filemaker.com/xml/fmresultset" version="1.0">
<error code="0" />
<product build="03/01/2005" name="FileMaker Web Publishing Engine" version="7.0v5" />
<datasource database="elected_officials_sync" date-format="MM/dd/yyyy" layout="elected_officials" table="elected_officials" time-format="HH:mm:ss" timestamp-format="MM/dd/yyyy HH:mm:ss" total-count="7923" />
- <metadata>
<field-definition auto-enter="no" global="no" max-repeat="1" name="ID" not-empty="yes" result="number" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="first" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="last" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="prefix" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="email" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="state" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="LD" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="kind" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="web" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="middle" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="emailMethod" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="emailformstring" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="address1" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="address2" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="city" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="zip" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="phone" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="fax" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="party" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="institution" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="suffix" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="active" not-empty="yes" result="number" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="address_state" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="no" global="no" max-repeat="1" name="abbreviation" not-empty="no" result="text" type="normal" />
<field-definition auto-enter="yes" global="no" max-repeat="1" name="creationDate" not-empty="no" result="timestamp" type="normal" />
</metadata>
- <resultset count="7923" fetch-size="25">
- <record mod-id="0" record-id="23232">
- <field name="ID">
<data>400001</data>
</field>
- <field name="first">
<data>James</data>
</field>
- <field name="last">
<data>Elkins</data>
</field>
- <field name="prefix">
<data>Representative</data>
</field>
- <field name="email">
<data>Rep_Jim_Elkins@legis.state.ak.us</data>
</field>
- <field name="state">
<data>AK</data>
</field>
- <field name="LD">
<data>AK_001</data>
</field>
- <field name="kind">
<data>SH</data>
</field>
- <field name="web">
<data>http://w3.legis.state.ak.us/house/24/ELN.php</data>
</field>
- <field name="middle">
<data>B.</data>
</field>
- <field name="emailMethod">
<data>e</data>
</field>
- <field name="emailformstring">

YZlat

I think your xpath is incorrect

YZlat

try

Dim xpath = "//field[@name='first']"

Dim node as XmlNode=n.SelectSingleNode(xpath)
If Not node Is Nothing Then
Response.Write("--" & node.InnerText)
End if

YZlat

actually use this:

Dim xpath = "//field[@name='first']"

Dim node as XmlNode=n.SelectSingleNode(xpath)
Dim dataNode As XmlNode
If Not node Is Nothing Then
dataNode=node.SelectSingleNode("data")
Response.Write("--" & dataNode.InnerText)
End if

alisman

ASKER

no dice. this xpath expression is returning "Nothing" ???

Dim xpath = "//field[@name='first']"

alisman

ASKER

the following lines of code work find:

Response.Write(n.ChildNodes.Item(0).Attributes(0).InnerText)

Response.Write(n.ChildNodes.Item(0).FirstChild.InnerText)

So, it's something wrong with the selectSingleNode and the xpath expression.

ASKER CERTIFIED SOLUTION

Carl Tawn

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alisman

ASKER

thank you very much carl.