QueryError "It is error for context item undefined when using[err:XPDY0002]

Question

Hi,
I a beginner for DB XML with python, below is my script and i have error
"def next(*args): return _dbxml.XmlResults_next(*args)
RuntimeError: Error: It is an error for the context item to be undefined when using it [err:XPDY0002], <query>:1:12" when i executed my scripts. Pls advice. Thank you.
import sys
from dbxml import *
from bsddb3.db import *
class DbXml:
def createEnvironment(self, home):
""" Create DBEnv and initialize XmlManager"""
try:
environment = DBEnv()
environment.open(home, DB_RECOVER|DB_CREATE|DB_INIT_LOCK|
DB_INIT_LOG|DB_INIT_MPOOL|DB_INIT_TXN, 0)
except DBError, exc:
print exc
sys.exit()
try:
mgr = XmlManager(environment, 0)
except XmlException, se:
print se
sys.exit()
return mgr
def closeEnvironment(self):
""" Close DBEnv environment"""
environment = DBEnv()
environment.close()
def createContainer(self, mgr, containerName):
""" Create/open a node container"""
if mgr.existsContainer(containerName) != 0:
mgr.removeContainer(containerName)
try:
return mgr.createContainer(containerName,
DBXML_TRANSACTIONAL|DBXML_ALLOW_VALIDATION,
XmlContainer.NodeContainer)
except XmlException, ex:
print ex
sys.exit()
def putDocument(self, mgr, cont, file, DocName):
""" put xml document in database"""
self.docName = DocName
f = open(file)
q = f.read()
f.close()
try:
# all Container modification operations need XmlUpdateContext
uc = mgr.createUpdateContext()
txn = mgr.createTransaction()
try:
docName = cont.putDocument(txn, self.docName,
q, uc) #, DBXML_GEN_NAME)
txn.commit()
except XmlException, ex:
print ex
txn.abort()
txn = mgr.createTransaction()
doc = cont.getDocument(txn, self.docName)
name = doc.getName()
docContent = doc.getContentAsString()
txn.commit()
print "Document name: ",name,"\nContent: ",docContent
except XmlException, inst:
print inst
if txn:
txn.abort()
def query(self, mgr, cont, queries):
""" Query"""
myQuery = r"collection(" + cont + ")" + "/" + queries
myContainer = mgr.openContainer(cont)
qContext = mgr.createQueryContext()
qContext.setEvaluationType(XmlQueryContext.Lazy)
results = mgr.query(myQuery, qContext)
for value in results:
document = value.asDocument()
name = document.getName()
content = value.asString()
print name, ":", content
if __name__ == "__main__":
dbxml = DbXml()
mgr = dbxml.createEnvironment(".")
cont = dbxml.createContainer(mgr, "test.dbxml")
dbxml.putDocument(mgr, cont, "C:\Documents and Settings\uidc0998\Desktop\\books.xml", "books.xml")
dbxml.query(mgr, "test.dbxml", "bookstore/book/title")
dbxml.closeEnvironment()
Edited by: user10951778 on Mar 31, 2009 5:47 PM

Answer 1

Hi rucong.zhao,
Below is my xml, may i know what type of namespace or what i should put for namespace? Thank you.
<bookstore>
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="WEB">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
<book category="WEB">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>