issue with reading xml file!

Dear all,

i tried to read an xml file using xmlread but got a long error msg:

Error using xmlread (line 116)

Java exception occurred:

org.xml.sax.SAXParseException; systemId:

file:/C:/All%20Matlab%20Data%20Analysis%202023/convert%20xml%20to%20mat/Example_xmlfile.xml; lineNumber: 29;

columnNumber: 3; The markup in the document following the root element must be well-formed

my xml formt is attached (As text format as xml is not support for uoloading).

appreciated output is:

Main1 eFun1 a1 A1A

Main1 eFun1 a2 0

Main1 eFun1 a3 3

Main1 eFun1 a4 B1B

Main1 eFun2 b1 1

Main1 eFun2 b2 1

Main1 eFun2 b3 0

Main1 eFun3 c1 202

Main1 eFun3 c2 -13

Main1 eFun3 c3 4

Main2 bFun1 x1 Ngb

Main2 bFun1 x2 0

Main2 bFun1 x3 4

Main2 bFun1 x4 a0a

Main2 bFun2 y1 0

Main2 bFun2 y2 cnc

Main2 bFun2 y3 4

Main2 bFun2 y4 69

Thank you,

Br.

Joseph

Answer 1

[Harsh Mahalwar]

Hi Joseph,

You can use the parseXML function given in the following documentation to read your xml file.

https://in.mathworks.com/help/matlab/ref/xmlread.html

Just remember to change the tag names accordingly!

Thanks and regards,

Harsh Mahalwar

[joseph chahin]

Thx Mahalwar for teh reaction!

tried byt got the following msg:

>> parseXML('Example_xmlfile.xml')

Error using parseXML (line 6)

Failed to read XML file Example_xmlfile.xml.

must I define or specify something?

Br.

Joseph

Answer 2

[Kevin Gurney]

Hi Joseph,

The xmlread parsing error you are encountering appears to be related to the fact that you have more than one root-level node in your XML document (specifically, there are two spec:syndata nodes at the the top-level).

An easy way to verify that this is causing the issue is to add a new root node to the document that wraps all the other nodes (I've called this node <root> for simplicity in the example below).

<root>

<spec:syndata FunctionType="Main2" xmlns:spec="foo">

<class>

<eFun1>

<attributes>

<a1>A1A</a1>

<a2>0</a2>

<a3>3</a3>

<a4>B1B</a4>

</attributes>

</eFun1>

</class>

<class>

<eFun2>

<attributes>

<b1>1</b1>

<b2>1</b2>

<b3>0</b3>

</attributes>

</eFun2>

<eFun3>

<attributes>

<c1>202</c1>

<c2>1</c2>

<c3>-13</c3>

</attributes>

</eFun3>

</class>

</spec:syndata>

<spec:syndata FunctionType="Main2">

<class>

<bFun1>

<attributes>

<x1>Ngb</x1>

<x2>0</x2>

<x3>4</x3>

<x4>a0a</x4>

</attributes>

</bFun1>

</class>

<class>

<bFun2>

<attributes>

<y1>0</y1>

<y2>cnc</y2>

<y3>4</y3>

<y4>69</y4>

</attributes>

</bFun2>

</class>

</spec:syndata>

</root>

With this change, you should be able to read this file using xmlread without any issues.

Best Regards,

Kevin Gurney

[joseph chahin]

Hoi Kevin, Thx for the tip.

I tried but no yet there:

i got the following:

>> xmlread('Example_xmlfileNew.xml')

ans =

[#document: null]

[Stephen23]

"I tried but no yet there"

The NULL does not mean that the import failed, it means that the "document" node has no value... which is completely correct for your file:

dom = xmlread('Example_xmlfile.txt')

dom =

[#document: null]

Of course that node can contain other nodes, which yours does. The first node which contains a value is "a1":

one = dom.getElementsByTagName('a1');
two = one.item(0)

two =

[a1: null]

txt = two.item(0)

txt =

[#text: A1A]

getNodeValue(txt)

ans =

A1A

Read the Apache Xerces-J documentation carefully, otherwise you won't get far working with this data:

https://www.mathworks.com/help/matlab/ref/xmlread.html

And Kevon Gurney is correct: the XML standard specifies that every document must contain exactly one root element: "XML documents must contain one root element that is the parent of all other elements"

https://www.w3schools.com/xml/xml_syntax.asp

[Tatjana]

Hi Stephen23,

could you possibly explain, why one needs to enter "....item(0)" twice in that example? I tried this example and an example of my own that's similar and you are right (though the method does not really work with this example: https://de.mathworks.com/help/matlab/ref/matlab.io.xml.dom.nodelist-class.html) So when I enter "....item(0)" the first time with "two = one.item(0)" where are we exactly? Inside <a1> but not in between <a1>...<a1>?

My second question refers to the children nodes. Which command gives you the listing of all <attributes>-belongings such as <a1>A1A</a1>, <a2>0</a2> <a3>3</a3> <a4>B1B</a4>?

Thanks

[Stephen23]

"where are we exactly? Inside <a1> but not in between <a1>...<a1>? "

As far as I can tell the first ITEM call selects which node, whereas the second ITEM call refers to the content of the node. Clearly there could be multiple nodes with the same name so we need to unambiguously select which one we want to refer to, and then any single node can have multiple content (text and other nodes) so once again we need to select which one we want to refer to.

Here I modified the file so that it contains two "a1" nodes:

dom = xmlread('Modified_xmlfile.txt');
one = dom.getElementsByTagName('a1');
one.item(0).item(0)

ans =

[#text: A1A]

one.item(1).item(0)

ans =

[#text: 1]

"though the method does not really work with this example..."

I would not expect a different tool to work in the same way.