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Ian (Fluxtah) Warwick's blog RSS 2.0
# Wednesday, December 16, 2009
Sharepoint missing fields in NewForm for custom list definition and content type

I created a custom content type and list definition, after upgrading my sharepoint solution I could see the list and content types under the new menu but when creating a new item, the fields were missing from NewForm.aspx

I discovered that it was due to the ContentType definition not having the FieldRefs tag, my content type was defined like this:-

  <ContentType ID="0x01001376F571B0DB9D4E9384D2927DC110CF02" Name="News Article" Group="Vodafone LCD Content Types" Version="0">
  </ContentType>

When it should have been like this:-

  <ContentType ID="0x01001376F571B0DB9D4E9384D2927DC110CF02" Name="News Article" Group="Vodafone LCD Content Types" Version="0">
    <FieldRefs>
    </FieldRefs>
  </ContentType>

Wednesday, December 16, 2009 8:38:54 AM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
Sharepoint
# Wednesday, November 25, 2009
Testing for a whole number in C#

I was thinking about this, for some reason, and thought it would be good to remind myself of those little useful bits of code that you never really use much then sometimes wonder how to do them.

So my first tidbit, is to test if a number is a whole number, here is my solution, any better solution than this, answers on a postcard please.

void Main()
{
    decimal decimalNumber = 4.9M;
    decimal wholeNumber = 5;
    
    Console.WriteLine(Math.Floor(decimalNumber) == decimalNumber); // Returns false;
    Console.WriteLine(Math.Floor(wholeNumber) == wholeNumber); // Returns true;
}

 

Wednesday, November 25, 2009 10:39:40 AM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
C#
# Friday, November 13, 2009
C# XML serialization and inheritance

I wrote a small console application to test if this was possible and it turns out all you need is an XmlInclude attribute on the base type of the sub-types you are serializing.

In the following example Ninja and Customer inherit from Person, Person is decorated with the XmlInclude attribute for both Ninja and Customer.

class Program
 {
     static void Main(string[] args)
     {
         XmlSerializer serializer = new XmlSerializer(typeof(Stuff));
         Stuff stuff = new Stuff()
         {
             People = new List<Person>()
             {
                 new Person() { Name = "<b>Bob</b>", Type="Person" },
                 new Ninja() { Name = "Hiro", Type="Ninja", Weapon = "Shuriken" },
                 new Customer() { Name = "Fred", Type = "Customer", CustomerId = "1234"}
             }
         };

         serializer.Serialize(Console.Out, stuff);
     }
 }

 public class Stuff
 {
     public List<Person> People { get; set; }
 }

 [XmlInclude(typeof(Ninja)), XmlInclude(typeof(Customer))]
 public class Person
 {
     public string Type { get; set; }
     public string Name { get; set; }
 }

 public class Ninja : Person
 {
     public string Weapon { get; set; }
 }

 public class Customer : Person
 {
     public string CustomerId { get; set; }
 }
Friday, November 13, 2009 7:56:37 AM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
C#
# Wednesday, November 11, 2009
Country table data sql script

It comes to that point in time when you need a country table in your database and you do not have a list to import at hand, after scouring the web a bit, everything seemed to be out of date, so I wrote a little script to scrape the details from a wikipedia page for the ISO 3166-1 standard for country codes.

I wrote and ran the following quick & dirty JQuery script on that page.

if($('#output_textarea').length == 0){
    $(document.body).append($('<textarea rows="128" id="output_textarea"></textarea>'));
}

document.output_textarea_val = "";

$('#sortable_table_id_0 tr').each(function(idx){

    if(idx > 0){
        document.output_textarea_val += "INSERT INTO country (name, code_alpha_2, code_alpha_3, code_numeric) VALUES(";
        var cells = $('td', this), cellLen = cells.length;
        cells.each(function(cellIdx){
            if(cellIdx < 4){
            document.output_textarea_val += "\"" + $(this).text().trim() + "\"";
            if(cellIdx < cellLen - 2){
            document.output_textarea_val += ", ";
            }
            }
        });
        document.output_textarea_val += ');\n';
    }
});

$('#output_textarea').val(document.output_textarea_val);

This script creates insert statements for mySQL and inserts the results into a text box at the foot of the page, in order for it to work you need to inject jQuery into the document, you can do this with the jQueryify Bookmarklet.

I have tested this script and it qualifies for the "works on my machine" certification programme.

The script produces the following output.

Wednesday, November 11, 2009 1:07:31 PM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
Javascript | SQL
# Tuesday, September 15, 2009
Interface or Delegate?

Whilst working on my network engine I came across a problem that I initially solved with an interface, but it turned out that the class that implemented this interface exposed public methods that I really wanted to be private, an example will explain the problem. 

public interface IMessageReceiver
{
    void Receive(string message);
}

public interface IMessageProvider
{
    IMessageReceiver MessageReceiver;
    void Update();
}

public class ConcreteReceiver: IMessageReceiver
{
    private IMessageProvider _MessageProvider;

    public ConcreteReciever(IMessageProvider messageProvider)
    {
        _MessageProvider = messageProvider;
        _MessageProvider.MessageReceiver = this;
    }
    public void Receive(string message)
    {
        Console.WriteLine(message);
    }

    public void Update()
    {
        MessageProvider.Update();
    }
}

When calling ConcreteReceiver.Update(), this will call MessageProvider.Update(), then, the concrete implementation of IMessageProvider should call IMessageReceiver.Receive, effectively like a callback.

Now the issue in my case was that I did not want the Receive method of ConcreteReceiver to be public, but of course any concrete type that implements an interface must implement those methods as public, after pondering a while I realised the design was actually flawed anyway, what I really wanted was a callback, so I changed my design as follows.

public interface IMessageProvider
{
    Action<string> ReceiveAction;
    void Update();
}

public class ConcreteReceiver
{
    private IMessageProvider _MessageProvider;

    public ConcreteReciever(IMessageProvider messageProvider)
    {
        _MessageProvider = messageProvider;
        _MessageProvider.ReceiveAction = Receive;
    }
    private void Receive(string message)
    {
        Console.WriteLine(message);
    }

    public void Update()
    {
        MessageProvider.Update();
    }
}

So now my Receive method on my ConcreteReceiver can be private, since I am now using a generic Action<T> delegate, this prevents my public API exposing methods that are really meant to be only used internally.

Tuesday, September 15, 2009 3:50:00 AM (GMT Daylight Time, UTC+01:00)  #    Comments [1] -
C#
# Wednesday, September 09, 2009
Socket.Available and UDP

The Available property of the System.Net.Sockets class will tell you how much data is available to read.

With UDP sockets, one thing to remember is that Socket.Available will give the total size of all the datagrams ready to read, so to the only way to know how many datagrams are waiting to be read is to call ReceiveFrom repeatedly until all data is read, for instance:- 

while(Socket.Available > 0)
{
   int datagramSize = Socket.ReceiveFrom(buffer, ref endPoint);
}

The datagramSize variable will give the size of the datagram that was read, this can be troublesome to manage since you do not know what you are going to get, until you get it, so you would need to initialize a large enough buffer to hold the datagram.

In the networking framework I am currently writing, the application has a configurable MaxPacketSize option so I can initialize my buffer to this size, but this wont help in the event that a bum packet is sent that breaches this constraint so some error handling would also need to be in place to compensate for this issue.

Wednesday, September 09, 2009 5:26:00 PM (GMT Daylight Time, UTC+01:00)  #    Comments [0] -
C#
# Sunday, March 08, 2009
ASP.NET MasterType Directive

A cool thing, did not realise this, you can use a @MasterType directive in an ASP.NET page to strongly type the Master property, quite cool. 

<%@ MasterType TypeName="BaseMaster" %>
Sunday, March 08, 2009 3:59:00 PM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
General | ASP.NET
Handling IHttpModule Events in Global.asax

This is cool, if you write your own http module by implementing IHttpModule you can subscribe to any events that it raises in the Global.asax, just like you would with Application_Start, Application_End, etc you can do the same with your own events with the signature ModuleName_EventName.

So if you had a IHttpModule, say, StatsModule with an event, Start, you can subscribe to the start event with StatsModule_Start.

Its described on this MSDN Docs page for ASP.NET Application Life Cycle Overview for IIS 5.0 and 6.0.

Very cool!

Sunday, March 08, 2009 1:00:00 AM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
ASP.NET
# Saturday, March 07, 2009
ASP.NET Tilde (~) Prefixed URLs, resolving for client controls

It can be quite handy to use the ~ with ResolveUrl or for url properties of server controls, however, it does not work for ordinary markup, for instance: 

<a href="~/Foo/Bar.aspx"></a>

would not work since you have to add the runat="server". You can work around this with the following if you happen to have access to Page:

<a href="<%=ResolveUrl("~/Foo/Bar.aspx") %>"></a>

But what if you do not have access to Page? Well, there is the option of rolling your own ResolveUrl, which is the approach I have taken many times.

I am still on a mission brushing up on my ASP.NET and found a community comment on the MSDN Docs for ASP.NET Web Site Paths that has a out-of-the-box way of doing this as follows: 

<a href="<%=System.Web.VirtualPathUtility.ToAbsolute("~/Foo/Bar.aspx")%>"></a>

 Very handy! and its been in since .NET 2.0 so it shows how much I am missing out on by not thumbing through the ASP.NET docs.

Saturday, March 07, 2009 3:31:00 AM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
ASP.NET
# Friday, March 06, 2009
Validating ASP.NET Pages with W3C Validation Service

According to the ASP.NET Docs on XHTML Conformance if you try to validate an ASP.NET page with the W3C XHTML validation service it might not report it as valid XHTML simply because the W3C validation service does not report itself as a browser that ASP.NET recognises.

You can get around this problem by creating a browser definition in a .browser file that you put into your App_Browsers folder of your ASP.NET website.

Yoinked directly from the docs: 

<browsers>
  <browser id="W3C_Validator" parentID="default">
    <identification>
        <userAgent match="^W3C_Validator" />
    </identification>
    <capabilities>
      <capability name="browser"              value="W3C Validator" />
      <capability name="ecmaScriptVersion"    value="1.2" />
      <capability name="javascript"           value="true" />
      <capability name="supportsCss"          value="true" />
      <capability name="tables"               value="true" />
      <capability name="tagWriter" 
         value="System.Web.UI.HtmlTextWriter" />
      <capability name="w3cdomversion"        value="1.0" />
    </capabilities>
  </browser>
</browsers>

This might just be handy to know at some point, although most good browser based web dev tool suites offer the ability to validate XHTML, and I believe they send the content to validate from rendered markup in your browser.

Friday, March 06, 2009 6:21:00 AM (GMT Standard Time, UTC+00:00)  #    Comments [0] -
ASP.NET
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Ian Warwick
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