ProgramGood.Net - c# language

Default Values in Eval

Dave Mateer — Thu, 05 Aug 2010 02:25:49 GMT

I’m getting data using LINQ to SQL, then showing on the front end. If I want a null coming from the database to default to something:

<telerik:GridTemplateColumn HeaderText="Image" UniqueName="Image"> 


<ItemTemplate> 


<asp:Label ID="asdf" runat="server" Text='<%#
String.IsNullOrEmpty(Convert.ToString(Eval("Image1"))) ? "noImage.jpg"
: Eval("Image1")%>'></asp:Label>

<a href="<%=VirtualPathUtility.ToAbsolute("~/")%>showFrontEndMaterialDetail.aspx?materialId=<%#
Eval("Id")%>">

<img src="<%=VirtualPathUtility.ToAbsolute("~/")%>Images/Uploaded/Thumbs/<%#
Eval("Image1") ?? "noPhoto.jpg"
%>"></img></a>



</ItemTemplate> 


</telerik:GridTemplateColumn>

Thanks to these people:

http://stackoverflow.com/questions/3411155/c-eval-aspx-fun

http://stackoverflow.com/questions/3410942/linq-to-sql-default-value-nullable

Difference Between a Property and a Field using Repeaters

Dave Mateer — Wed, 04 Aug 2010 23:04:00 GMT

When displaying a repeater on an aspx page:

<asp:Repeater ID="Repeater1" runat="server">

<ItemTemplate>

<%#DataBinder.Eval(Container.DataItem, "FileName")%>

</ItemTemplate>

</asp:Repeater>

or shorter:

<asp:Repeater ID="Repeater1" runat="server">

<ItemTemplate>

<%#Eval("FileName")%>

</ItemTemplate>

</asp:Repeater>

It is important to remember to make FileName a property and not just a public field ie this works

public class ImageThing

{

public string FileName
{get; set; }

}



private void DisplayThumbnailImages()

{

ImageThing imageThing1 = new ImageThing();

ImageThing imageThing2 = new ImageThing();

imageThing1.FileName = "asdf.jpg";

imageThing2.FileName = "aaa.jpg";



List<ImageThing> imagesToRender = new List<ImageThing>();

imagesToRender.Add(imageThing1);

imagesToRender.Add(imageThing2);



Repeater1.DataSource = imagesToRender;

Repeater1.DataBind();

}

this doesn’t

public class ImageThing

{

public string FileName;

}

A property encapsulates a field.

Anonymous Types

Dave Mateer — Wed, 23 Jun 2010 03:35:49 GMT

While trying to figure out what is meant by the 3rd new section in a view in MVC

<%: Html.ActionLink("Edit", "Edit", new { id=item.DinnerID }) %>

So it is really creating an object with a single property id, which is an int, equal to that of the item, which is a Dinner.

“Anonymous types provide a convenient way to encapsulate a set of read-only properties into a single object without having to first explicitly define a type”

class Program

{

static void Main(string[]
args)

{

// Anonymous types provide a convenient way to encapsulate
a set of read-only properties


// into a single object without having to first explicitly
define a type


var person = new { Name = "Terry",
Age = 21 };

Console.WriteLine("name is " + person.Name);

Console.WriteLine("age is " + person.Age.ToString());



// Anonymous types just get rid of Person1 really.


Person1 person1 = new Person1 { Name = "Bill",
Age = 55 };

Console.WriteLine("name is " + person1.Name);

Console.WriteLine("age is " + person1.Age.ToString());

}

}



class Person1

{

public string Name
{ get; set; }

public int Age
{ get; set; }

}

Many thanks to the question here for clarifying:

http://stackoverflow.com/questions/3098643/anonymous-type-syntax-in-asp-net-mvc

Static Classes / Extension Methods

Dave Mateer — Thu, 11 Feb 2010 00:54:17 GMT

Static classes are usually used as ‘utility’ classes

You don’t need an instance

class Program

{

static void Main()

{

double result = thing.daveSubtract(10);

Console.WriteLine(result);

}

}



static class thing

{

static public double daveSubtract(double number)

{

return (number - 2);

}

}

Extension Methods

From: http://msdn.microsoft.com/en-us/library/bb383977.aspx

Extension methods enable you to "add" methods to existing types without creating a new derived type,

Extension methods are a special kind of static method, but they are called as if they were instance methods on the extended type.

For client code, there is no apparent difference between calling an extension method and the methods that are actually defined in a type.

using System;



namespace ConsoleApplication1

{

class Program

{

static void Main(string[]
args)

{

string s = "hello
extension methods are good";

Console.WriteLine(s);

int i = s.WordCount();

Console.WriteLine("number of words is {0}",
i.ToString());

}

}



public static class MyExtensions

{

public static int WordCount(this String
str)

{

return str.Split(new char[]
{ ' ', '.', '?' },
StringSplitOptions.RemoveEmptyEntries).Length;

}

}

}