Using KnockoutJS with SignalR in ASP.NET MVC

KnockoutJS is a MVVM implementation for JavaScript written by Steve Sanderson, in my opinion the author of the best ASP.NET MVC textbooks available. Simply put it lets you bind a JavaScript object model to your HTML UI using a Read more

A MongoDB Tutorial using C# and ASP.NET MVC

In this post I'm going to create a simple ASP.NET MVC website for a simple blog that uses MongoDB and the offical 10gen C# driver. MongoDB is no NOSQL database that stores information as Binary JSON (BSON) in documents. I Read more

Linq To SQL Tutorial

Check out some of my other Linq to SQL posts: EntityBase Inheritance Modifiers with SQLMetal Linq to SQL with WCF Services Linq to SQL Framework (Repository/Business wrapper) ObjectDataSource binding with server side paging and sorting Load Options Generic Framework using reflection This is a basic tutorial for Read more

JSON Serialization using the DataContractJsonSerializer and C#

Posted on by Joe in ASP.NET, C#, JavaScript | 4 Comments

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Previously I’d done JSON serialization using the JavaScriptSerializer which is part of AJAX Extensions 1.0, but this is now obsolete.

.NET 3.5 introduced the DataContractJsonSerializer class.  The class sits in the System.Runtime.Serialization.Json namespace which is curiously hidden away in the System.ServiceModel.Web assembly.

The DataContractJsonSerializer can serialize a class that contains the Serializable attribute or any class defined as a DataContract.

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JavaScript inline if statement

Posted on by Joe in JavaScript | Leave a comment

The JavaScript inline if statement is identical to the one in C#:

var forename = (gender == 'male') ? 'Joe' : 'Emily';

Escape curly braces when using String.Format or StringBuilder.AppendFormat

Posted on by Joe in C#, JavaScript | 2 Comments

I was using the StringBuilder to create a JSON string which included an array and therefore curly braces, but I got an exception as curly braces are used to define the parameters for the format.

sb.AppendFormat("{\"Forename\":\"{0}\",\"Surname\":\"{1}\"}", person.Forename, person.Surname);

At first I tried adding a backslash which is used to escape the quotation mark but this didn’t work, so I tried the double character trick but adding two curly braces which seems to do the job.

sb.AppendFormat("{{\"Forename\":\"{0}\",\"Surname\":\"{1}\"}}", person.Forename, person.Surname);

Linq to SQL Tutorial – Linq to SQL Generic Framework using reflection

Posted on by Joe in ASP.NET, C#, Linq | 1 Comment

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In a previous post; Base Repository/Business Logic wrapper, I talked about a basic Linq to SQL Framework I created. I then extended it in my ObjectDataSource binding with paging and sorting post to show how to use it with the ObjectDataSource.

The problem was that although it worked quite nicely for getting all records and getting by ID, if I wanted to perform any specific filtering I had to create a derived repository class with a specific method for each query.

In this post I’ll explain how I have extended this framework using reflection to allow filtering on multiple columns without having to created separate repository objects.

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Linq to SQL Tutorial – Using Load Options to preload data immediately without lazy loading

Posted on by Joe in ASP.NET, C#, Linq | 1 Comment

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With Linq to SQL lazy loading is used by default. That means that if one object contains another object, the child object will only be loaded when first accessing it. Using Load Options it is possible to tell Linq to SQL to also load the child object at the same time as loading it’s parent.

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ASP.NET FormView SetFocus

Posted on by Joe in ASP.NET, C# | 1 Comment

I have FormView and on changing to Edit mode I wanted to set focus to the first textbox. I thought I’d do this hooking into the ModeChanged event but this doesn’t work as the textbox hasn’t been rendered.

I then tried overriding the Render method and setting the focus after rendering; at this point the control was created but I get an exception to say focus can only be set in PreRender, but in PreRender the control won’t be available.

One way I found to get this to work was to set the focus in a handler for the DataBound event of the FormView.

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Read only Automatic Properties in C#

Posted on by Joe in C# | 1 Comment

Automatic Properties were a nice addition to C# 3 and I use them all the time. A lot of people may already know this but somehow I only found out this week; you can create a read only automatic property simply by adding the ‘private’ keyword before ‘set’:


public class UserEventArgs : EventArgs
{
    public UserEventArgs(int userID)
    {
        UserID = userID;
    }

    public int UserID { get; private set; }
}

Desktop wallpaper across dual monitors

Posted on by Joe in Personal | Leave a comment

Yesterday I stitched together a few images of Sydney Harbour that I took on my way to work:

Sydney Harbour

I wanted to make it a wallpaper over both of my monitors. When playing around with the settings I found that the only option that seemed to do anything over both monitors was TILE.  I resized the image so the height of the image matched the resolution of my monitors, then set it as a tiled wallpaper, which due to the size just showed the image once over both monitors.

Convert file size bytes to megabyte/gigabyte string using C#

Posted on by Joe in C# | 11 Comments

I feel like I haven’t posted in ages. Have been busy changing job and moving house but I have a list of things I want to blog about soon.

Recently I needed to convert a number of bytes to a readable string that represents the number of kilobytes, megabytes or gigabytes.

I created an extension method for Int32 which does this for me Int64 as per Alex’s comment about the FileInfo.Length property being a long. I also changed my method for Int32 to call the other method so that it can be used for both int and long.

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Linq Tutorial – Using the Enumerable.Any extension method

Posted on by Joe in ASP.NET, C#, Linq | Leave a comment

Consider the following:

Entities

Using Linq I want to select all the roles for a particular user. I could create a query like this:

 

public List<Role> GetByUserID(int userID)
{
    List<Role> roles = (from r in Context.Roles
                       join ur in Context.UserRoles on r.ID equals ur.RoleID
                       where ur.UserID.Equals(userID)
                       select r).ToList();

    return roles;

}

This simply creates the following SQL:

SELECT [t0].[RoleID] AS [ID], [t0].[Name]
FROM [dbo].[Role] AS [t0]
INNER JOIN [dbo].[UserRole] AS [t1] ON [t0].[RoleID] = [t1].[RoleID]
WHERE [t1].[UserID] = @p0

Alternatively I could use the Any extension method.

public List<Role> GetByUserID(int userID)
{
    return Context.Roles.Where(r => r.UserRoles.Any<UserRole>(ur => ur.UserID.Equals(userID))).ToList();
}

The Any method returns a bool which indicates if any of the UserRoles meet the lambda expression; in this case checking the UserID property. The Where method evaluates the Roles against the Roles the User belongs to so we only get those Roles.

The resulting SQL looks like this:

SELECT [t0].[RoleID] AS [ID], [t0].[Name]
FROM [dbo].[Role] AS [t0]
WHERE EXISTS(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[UserRole] AS [t1]
    WHERE ([t1].[UserID] = @p0) AND ([t1].[RoleID] = [t0].[RoleID])
    )