xmlread - Read XML document and return Document Object Model node

Syntax

Description

DOMnode= xmlread(filename) reads the specified XML file and returns a Document Object Model node representing the document.

Tips

The display for a properly parsed document is [#document: null]. For example,

xDoc = xmlread('info.xml')

returns

xDoc =
[#document: null]

Input Arguments

filename

String enclosed in single quotation marks that specifies the name of the local file or URL.

Output Arguments

DOMnode

Document Object Model node, as defined by the World Wide Web consortium. For more information, see What Is an XML Document Object Model (DOM)?.

Examples

The root element in an XML file sometimes includes an xsi:noNamespaceSchemaLocation attribute. The value of this attribute is the name of the preferred schema file. Call the getAttribute method to get this value:

xDoc = xmlread(fullfile(matlabroot,'toolbox',...
               'matlab','general','info.xml'));

xRoot = xDoc.getDocumentElement;
schema = char(xRoot.getAttribute('xsi:noNamespaceSchemaLocation'))

This code returns:

schema =
http://www.mathworks.com/namespace/info/v1/info.xsd

Create functions that parse data from an XML file into a MATLAB structure array with fields Name, Attributes, Data, and Children:

function theStruct = parseXML(filename)
% PARSEXML Convert XML file to a MATLAB structure.
try
   tree = xmlread(filename);
catch
   error('Failed to read XML file %s.',filename);
end

% Recurse over child nodes. This could run into problems 
% with very deeply nested trees.
try
   theStruct = parseChildNodes(tree);
catch
   error('Unable to parse XML file %s.',filename);
end


% ----- Subfunction PARSECHILDNODES -----
function children = parseChildNodes(theNode)
% Recurse over node children.
children = [];
if theNode.hasChildNodes
   childNodes = theNode.getChildNodes;
   numChildNodes = childNodes.getLength;
   allocCell = cell(1, numChildNodes);

   children = struct(             ...
      'Name', allocCell, 'Attributes', allocCell,    ...
      'Data', allocCell, 'Children', allocCell);

    for count = 1:numChildNodes
        theChild = childNodes.item(count-1);
        children(count) = makeStructFromNode(theChild);
    end
end

% ----- Subfunction MAKESTRUCTFROMNODE -----
function nodeStruct = makeStructFromNode(theNode)
% Create structure of node info.

nodeStruct = struct(                        ...
   'Name', char(theNode.getNodeName),       ...
   'Attributes', parseAttributes(theNode),  ...
   'Data', '',                              ...
   'Children', parseChildNodes(theNode));

if any(strcmp(methods(theNode), 'getData'))
   nodeStruct.Data = char(theNode.getData); 
else
   nodeStruct.Data = '';
end

% ----- Subfunction PARSEATTRIBUTES -----
function attributes = parseAttributes(theNode)
% Create attributes structure.

attributes = [];
if theNode.hasAttributes
   theAttributes = theNode.getAttributes;
   numAttributes = theAttributes.getLength;
   allocCell = cell(1, numAttributes);
   attributes = struct('Name', allocCell, 'Value', ...
                       allocCell);

   for count = 1:numAttributes
      attrib = theAttributes.item(count-1);
      attributes(count).Name = char(attrib.getName);
      attributes(count).Value = char(attrib.getValue);
   end
end

See Also

xmlwrite | xslt

How To

• What Is an XML Document Object Model (DOM)?
• Example — Finding Text in an XML File

Related Links

• DOM Package Summary (methods and properties for nodes)

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