Yosi Havia: April 2009

Friday, April 24, 2009

Don't use XmlDocument use XmlTextReader instead

Hi,
I had an assignment to read a 200 MB xml file
i dont think that XmlDocument can help me here...
so i found the XmlTextReader object that made a great job
and from this moment i always use XmlTextReader to read
xml file content, so here is my example:

lets say that i want to read this Test.xml file:


<?xml version="1.0" encoding="utf-8" ?>

<RootNode>

 <Child>

  <Item Att="1">A</Item>

  <Item Att="2">B</Item>

 </Child>

 <Child>

  <Item Att="3">C</Item>

  <Item Att="4">D</Item>

 </Child>

</RootNode>

and this function read all the attributes and content
of the Item node in the xml:


public void ReadXml()
{
    int iCodepage = 862;
    string sAttribute, sNodeValue;
    string sFilePath = @"Test.xml";
    StreamReader oFileStream = null;
    XmlTextReader reader = null;
    //@@@ Check if the file exists
    if (!File.Exists(sFilePath))
        return;

    //@@@ Get the file as XmlTextReader
    oFileStream =
    new StreamReader(sFilePath, Encoding.GetEncoding(iCodepage));
    reader = new XmlTextReader(oFileStream);

    //@@@ Loop through all the file
    while (reader.Read())
    {
        //@@@ If we in Item node
        if (reader.Name.Equals("Item") &&
         (reader.NodeType == XmlNodeType.Element))
        {
             //@@@ Get the Attribute (Att) value
             reader.MoveToAttribute("Att");
             sAttribute = reader.Value;
             Console.WriteLine(sAttribute);
             //@@@ Get the node value
             reader.MoveToElement();
             sNodeValue = reader.ReadInnerXml();
             Console.WriteLine(sNodeValue);
        }
   }
  }

Tuesday, April 21, 2009

The perfect c# singleton

Hi,
after several tries i got the perfect thread safety c# singleton


public class DbProxy
{
 private static DbProxy _oInstance = null;
 private static readonly object padlock = new object();
 
 // @@@ public "consructor"
 public static DbProxy Instance
 {
  get
  {
   if (DbProxy._oInstance == null)
   {
    lock (padlock)
    {
     if (DbProxy._oInstance == null)
     {
      DbProxy newDB = new DbProxy();
      System.Threading.Thread.MemoryBarrier();
      DbProxy._oInstance = newDB;
     }
    }
   }
   return DbProxy._oInstance;
  }
 }
 // @@@ private constructor
 private DbProxy()
 {

 }
}

Monday, April 13, 2009

Output Cache by the book

Hi,
i found the best way to implement Output Cache
we have only 2 steps to make it:

step 1
------
define in the Web.config some different cache profiles that u need:


<system.web>

 <caching>

  <outputCacheSettings>

   <outputCacheProfiles>

    <add name="profile1" duration="100" varyByParam="param1" />

    <add name="profile2" duration="100" varyByParam="None" />

   </outputCacheProfiles>

  </outputCacheSettings>

 </caching>

</system.web>

step 2
------
define in your pages the profile that u want to use:


<%@ OutputCache CacheProfile="profile1" %>

now, if we want to check if it works
all we have to is to make aspx page, and to play with his links
and check if the DateTime changed or not
TEST.aspx


 <%@ OutputCache CacheProfile="profile1" %>

 <html xmlns="http://www.w3.org/1999/xhtml" >

  <body>

       <form id="form1" runat="server">

           <%= DateTime.Now.ToString() %><br />

           <a href="?param1=1">1</a><br />

           <a href="?param1=2">2</a><br />

           <a href="?param1=3">3</a><br />

       </form>

  </body>

 </html>

Another small tip:
for disable the OutputCache(in the development environment for example) add location="None" in the appropriate profile in the web.config in this way:


<add name="profile1" duration="100" varyByParam="param1" location="None" />

Saturday, April 11, 2009

A new startup - create a permanent breakpoint

Hi,
with this line u can create a permanent breakpoint in c# applications:

System.Diagnostics.Debugger.Break();

recomanded and very useful

Wednesday, April 8, 2009

Send array of objects form client to server

Hi,
with this code u can send array of object form client to server in c#
u have to copy the client and server code from this post
and use this 2 dependencies:
1. JSON Code(Take js file)
2. Serialize Code(Take dll file)

THE SERVER CODE:


using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Newtonsoft.Json;
using System.Collections.Generic;

public partial class tbl1 : System.Web.UI.Page
{
    public string tempPerson;
    public string temp_arr;
    public List person_arr = new List< person >();
    protected void Page_Load(object sender, EventArgs e)
    {
        Person person = new Person();
        person.name = string.Empty;
        person.age = 0;
        string json1 = JavaScriptConvert.SerializeObject(person);
        tempPerson = json1;
        string json = JavaScriptConvert.SerializeObject(person_arr); 
        temp_arr = json;
    }
    protected void LinkButton1_Click(object sender, EventArgs e)       
    {
        person_arr = JavaScriptConvert.DeserializeObject< List< person > > 
        (hiData.Value);
    }
}
public class Person
{
    public string name;
    public int age;
}

THE CLIENT CODE:


<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Arr.aspx.cs" Inherits="tbl1" %>
<script src="json2.js" type="text/javascript"></script>
<script type="text/javascript">  
    var arr = <%=temp_arr%>;
    var p1 = <%=tempPerson%>;
    var hiDataID = '<%=hiData.ClientID%>';
    function add_to_arr(name, age)
    {
        var tempP = clone(p1);
        tempP.name = name;
        tempP.age = age;
        arr[arr.length] = tempP;
    }
    function add2Items()
    {
        add_to_arr("name1", 1);
        add_to_arr("name2", 2);
        var g = JSON.stringify(arr);
        document.getElementById(hiDataID).value = g;
    }
    function clone(obj)
    {
        return JSON.parse(JSON.stringify(obj));
    }
</script>
<form id="form1" runat="server">
<div>
    <input onclick="add2Items()" type="button" value="Create Array">
    <input id="hiData" type="hidden" runat="server">
</div>
<asp:linkbutton id="LinkButton1" onclick="LinkButton1_Click" runat="server">Send To Server</asp:linkbutton>
</form>

Yosi Havia