c# - Build XPath for node from XmlReader -
i writing application parses dynamic xml various sources , traverses xml , returns unique elements.
given large size of xml files using xmlreader parse xml structure due memory constraints.
public idictionary<string, int> discover(string filepath) { dictionary<string, string> nodetable = new dictionary<string, string>(); using (xmlreader reader = xmlreader.create(filepath)) { while (!reader.eof) { if (reader.nodetype == xmlnodetype.element) { if (!nodetable.containskey(reader.localname)) { nodetable.add(reader.localname, reader.depth); } } reader.read(); } } debug.writeline("the node table has {0} items.", nodetable.count); return nodetable; } this works treat , nice , performant, final piece of puzzle eludes me, trying generate xpath each element.
now, @ first seemed straight forward using this.
var elements = new stack<string>(); while (reader.read()) { switch (reader.nodetype) { case xmlnodetype.element: elements.push(reader.localname); break; case xmlnodetype.endelement: elements.pop(); break; case xmlnodetype.text: path = string.join("/", elements.reverse()); break; } } but gives me 1 part of solution. given wish return xpath every node in tree contains data , detect if given node tree contains nested collections of data.
i.e.
<customers> <customer id=2> <name>ted smith</name> <addresses> <address1> <line1></line1> </address1> <address2> <line1></line1> <line2></line2> </address2> </addresses> </customer> <customer id=322> <name>smith mcsmith</name> <addresses> <address1> <line1></line1> <line2></line2> </address1> <address2> <line1></line1> <line2></line2> </address2> </addresses> </customer> </customers> keeping in mind data dynamic , schema unknown.
so output should include
/customer/name /customer/address1/line1 /customer/address1/line2 /customer/address2/line1 /customer/address2/line2
i using recursive method rather push/pop. see code below
using system; using system.collections.generic; using system.linq; using system.text; using system.xml; using system.io; namespace consoleapplication1 { class program { static void main(string[] args) { string input = "<customers>" + "<customer id=\"2\">" + "<name>ted smith</name>" + "<addresses>" + "<address1>" + "<line1></line1>" + "</address1>" + "<address2>" + "<line1></line1>" + "<line2></line2>" + "</address2>" + "</addresses>" + "</customer>" + "<customer id=\"322\">" + "<name>smith mcsmith</name>" + "<addresses>" + "<address1>" + "<line1></line1>" + "<line2></line2>" + "</address1>" + "<address2>" + "<line1></line1>" + "<line2></line2>" + "</address2>" + "</addresses>" + "</customer>" + "</customers>"; stringreader sreader = new stringreader(input); xmlreader reader = xmlreader.create(sreader); node root = new node(); readnode(reader, root); } static bool readnode(xmlreader reader, node node) { boolean done = false; boolean endelement = false; while(done = reader.read()) { switch (reader.nodetype) { case xmlnodetype.element: if (node.name.length == 0) { node.name = reader.name; getattrubutes(reader, node); } else { node newnode = new node(); newnode.name = reader.name; if (node.children == null) { node.children = new list<node>(); } node.children.add(newnode); getattrubutes(reader, newnode); done = readnode(reader, newnode); } break; case xmlnodetype.endelement: endelement = true; break; case xmlnodetype.text: node.text = reader.value; break; case xmlnodetype.attribute: if (node.attributes == null) { node.attributes = new dictionary<string, string>(); } node.attributes.add(reader.name, reader.value); break; } if (endelement) break; } return done; } static void getattrubutes(xmlreader reader, node node) { (int = 0; < reader.attributecount; i++) { if (i == 0) node.attributes = new dictionary<string, string>(); reader.movetonextattribute(); node.attributes.add(reader.name, reader.value); } } } public class node { public string name = string.empty; public string text = string.empty; public dictionary<string, string> attributes = null; public list<node> children = null; } } 
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