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/*
* Berkeley DB XML .NET API
*
* Copyright (C) 2007 Jana Business Consulting Ltd. All rights reserved.
*
* For more information, see http://www.janabiz.com.
*
*/
using JanaBiz.Db;
using JanaBiz.DbXml;
using JanaBiz.DbXml.Exceptions;
using System.Text;
public class UpdateDocument
{
private static string theContainer = "namespaceExampleData.dbxml";
// Modifies an XML document that is stored in a DB XML container
private static void doUpdateDocument(XmlManager mgr, XmlContainer container,
string query, XmlQueryContext context, XmlTransaction txn)
{
System.Console.WriteLine("Updating documents for expression: '" + query + "'.");
System.Console.WriteLine("Return to continue: ");
System.Console.ReadLine();
// query for all the documents that we want to update
XmlResults results = mgr.Query(txn, query, context, new XmlDocumentConfig());
System.Console.WriteLine("Found " + results.Size +
" matching the expression '" + query + "'.");
// Get an update context.
using(XmlUpdateContext updateContext = mgr.CreateUpdateContext())
{
while(results.MoveNext())
{
XmlDocument document = results.Current.ToDocument();
// Retrieve the entire document as a single String object
string docString = document.StringContent;
System.Console.WriteLine("Updating document: ");
System.Console.WriteLine(docString);
// This next method just modifies the document string
// in a small way.
string newDocString = getNewDocument(mgr, document, context,
docString);
System.Console.WriteLine("Updating document...");
//Set the document's content to be the new document string
document.StringContent = newDocString;
// Now replace the document in the container
container.UpdateDocument(txn, document, updateContext);
System.Console.WriteLine("Document updated.");
}
}
}
private static string getNewDocument(XmlManager mgr, XmlDocument document,
XmlQueryContext context, string docString)
{
// Get the substring that we want to replace
string inventory = getValue(mgr, document,
"/*/inventory/inventory/text()", context);
// Convert the String representation of the inventory level to an
// integer, increment by 1, and then convert back to a String for
// replacement on the document.
int newInventory = System.Int32.Parse(inventory) + 1;
string newVal = newInventory.ToString();
// Perform the replace
StringBuilder strbuff = new StringBuilder(docString);
strbuff.Replace(inventory, newVal);
System.Console.WriteLine("Inventory was " + inventory +
", it is now " + newVal + ".");
return strbuff.ToString();
}
private static string getValue(XmlManager mgr, XmlDocument document, string query,
XmlQueryContext context)
{
// Perform the query
// The document provides the context for the query
using(XmlQueryExpression queryExpr = mgr.Prepare(null, query, context))
{
using(XmlValue docValue = new XmlValue(document))
{
using(XmlResults result = queryExpr.Execute(null, docValue, context, new XmlDocumentConfig()))
{
// We require a result set size of 1.
if(!result.MoveNext())
{
System.Console.WriteLine("Error! query '" + query +
"' returned a result size < 1");
throw new System.Exception("getValue found result set not equal to 1.");
}
// Get the value. If we allowed the result set to be larger than size 1,
// we would have to loop through the results, processing each as is
// required by our application.
return result.Current.ToString();
}
}
}
}
public static void Main(string[] args)
{
string envdir = parseArguments(args);
DbEnvironment dbEnv = null;
XmlManager mgr = null;
XmlContainer container = null;
try
{
// Open an environment
dbEnv = CreateDbEnvironment(envdir);
// Open an environment and manager
using(mgr = CreateManager(dbEnv))
{
// Open a transactional container
XmlContainerConfig containerconfig = new XmlContainerConfig();
containerconfig.Transactional = true;
using(container = mgr.OpenContainer(null, theContainer,
containerconfig))
{
// Start a transaction
using(XmlTransaction txn = mgr.CreateTransaction())
{
// Create a context and declare the namespaces
using(XmlQueryContext context = mgr.CreateQueryContext())
{
context.SetNamespace("fruits", "http://groceryItem.dbxml/fruits");
context.SetNamespace("vegetables", "http://groceryItem.dbxml/vegetables");
context.SetNamespace("desserts", "http://groceryItem.dbxml/desserts");
// update the document that describes Zapote Blanco (a fruit)
string query = "collection(\"" + theContainer +
"\")/fruits:item/product[text() = 'Zapote Blanco']";
doUpdateDocument(mgr, container, query, context, txn);
// Commit the writes. This causes the container write operations
// to be saved to the container.
txn.Commit();
}
}
}
}
}
catch(DbXmlException e)
{
System.Console.WriteLine("Error performing document update against " + theContainer);
System.Console.WriteLine(e.ToString());
}
finally
{
if(container != null)
{
container.Close();
}
if(mgr != null)
{
mgr.Close();
}
if(dbEnv != null)
{
dbEnv.Close();
}
}
}
public static DbEnvironment CreateDbEnvironment(string envdir)
{
DbEnvironmentConfig envconf = new DbEnvironmentConfig();
envconf.CacheSize = 50 * 1024;
envconf.AllowCreate = true;
envconf.InitializeCache = true;
envconf.Transactional = true;
envconf.InitializeLocking = true;
envconf.InitializeLogging = true;
envconf.RunRecovery = true;
envconf.ErrorWriter = System.Console.Out;
envconf.ErrorPrefix = "PREFIX";
DbEnvironment env = new DbEnvironment(envdir, envconf);
return env;
}
public static XmlManager CreateManager(DbEnvironment env)
{
XmlManagerConfig mgrconfig = new XmlManagerConfig();
mgrconfig.AdoptEnvironment = true;
try
{
return new XmlManager(env, mgrconfig);
}
catch(System.Exception e)
{
env.Close();
throw e;
}
}
private static void Usage()
{
System.Console.WriteLine("This program updates a document stored in a DB XML container.");
System.Console.WriteLine("You should run exampleLoadContainer before running this example.");
System.Console.WriteLine("You are only required to pass this command the path location of the");
System.Console.WriteLine("database environment that you specified when you loaded the examples data:");
System.Console.WriteLine();
System.Console.WriteLine("\t-h <dbenv directory>");
System.Console.WriteLine("For example:");
System.Console.WriteLine("\tupdateDocument.exe -h examplesEnvironment");
System.Environment.Exit(-1);
}
private static string parseArguments(string[] args)
{
string envdir = null;
for(int i = 0; i < args.Length; ++i)
{
string arg = args[i];
if((arg.StartsWith("-")
#if WIN32
|| arg.StartsWith("/")
#endif
) && arg.Length > 1)
{
switch(arg[1])
{
case 'h':
{
++i;
if(i >= args.Length)
{
System.Console.WriteLine("Invalid option: " + arg);
Usage();
}
envdir = args[i];
break;
}
default:
{
System.Console.WriteLine("Unknown option: " + arg);
Usage();
break;
}
}
}
else
{
System.Console.WriteLine("Too many arguments: " + arg);
Usage();
}
}
if(envdir == null)
{
System.Console.WriteLine("Environment directory not found.");
Usage();
}
return envdir;
}
}
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