Programming

ADO.NET Entity Framework – Code First Development Pattern

Lance Robinson — Thu, 14 Apr 2011 07:42:00 GMT

Here’s a quick start introduction to the ADO.NET Entity Framework Code First Development Pattern. For a more complete (but still intro) walkthrough, check out ScottGu’s blog.

At the time of this writing, you’ll need the EF 4.1 Release Candidate. After EF 4.1 is released you’ll no doubt be able to find it on the ADO.NET team blog.

1. Create a new empty ASP.NET MVC2 Web Application, add a reference to System.Data.Entity. If using the EF4.1 RC - add a reference to the EntityFramework dll that comes installed with it.

2. Add the model classes you’d like to represent your data objects. For example if you need to represent game nights, you might create a class called Game with properties that describe the game night date, location, and other information.

3. Create a “Context Class” that inherits DbContext, which contains nothing but DbSet<yourclassnamefromstep2> public properties. For example if you created in step 2 a class called “Game”, here you’d have a property defined as:

public DbSet<Game> Games { get; set; }

At this point, EF code first will make certain assumptions (which we can override later if necessary) that allow us to write less code:

- The context class will map its properties (those DbSet properties) to tables with the same names (a Games table, in our example).

- Each row in that table will map to an instance of the model class (a Game instance, in our example).

- Properties in the model class are columns in the table.

- A property in the model class with the name “Id” or “<classname>Id” will be made the primary key.

- Relationships between tables are inferred if one model class has a property with the name “<otherclassname>Id”.

4. Add a controller to see EF Code First in action. For example, add Index (to just return a list of our game nights) and Create actions (to create a new game night).

5. Add the views (Index: strongly typed IEnumerable of Game, Create: strongly typed Game – content Create).

6. Create the database. One of those EF Code First assumptions is that it will automatically look for a connection string with the same name as the context class (eg, Games). Scott Guthrie recommends the use of SQL CE 4 for early development, and moving to SQL Server or SQL Express closer to the time of deployment.

Important: IF you’re using SQL CE or SQL Express, and your connection string points to a database file that does not yet exist, it will be automatically created for you!

Updating The Model

If you update the model (lets say we add a new property to our Game class), you’ll get an error the next time you attempt to run the application (“context has changed since the database was created”. EF Code First can handle this too: in Global.asax, add the following to the Application_Start event handler:

Database.SetInitializer<<yourContextClass>>(new RecreateDatabaseIfModelChanges<<yourContextClass>>());
RegisterRoutes(RouteTable.Routes);

Gu gives a nice tip – create a custom class that implements RecreateDatabaseIfMOdelChanges<<yourContextClass)> and overrides the Seed function to add “seed” rows to the database with default data. This way when we recreate the database after a model update, the database isn’t empty – but is seeded with our default data. Use this new custom class in the call to SetInitializer instead of RecreateDatabaseIfModelChanges.

Technorati Tags: ASPNET,MVC,Entity Framework,EF,Code First

Visual Studio 2010 Find and Replace With Regular Expressions

Lance Robinson — Thu, 10 Mar 2011 22:07:24 GMT

Here is a quick notes about using regular expressions in the VS2010 Find Replace dialog.

1. To create a backreference, use curly braces (“{“ and “}” ) instead of regular parentheses.

2. To use the captured backreference, use \1\2 etc, where \1 is the first captured value, \2 is the second captured value, etc.

Example:

I want to find*:

info.setFieldValue(param1, param2);

and replace it with:

SetFieldValue(info, param1, param2);

To do this, I can use the following find/replace values:

Find what:

{[a-zA-Z0-9]+}.setFieldValue${[a-zA-Z0-9., ]+}$;

Replace with:

SetFieldValue(\1, \2);

Use Regular Expressions is checked, of course.

*If you’re wondering why I’d want to do this – because I don’t have control over the setFieldValue function – its in a third party library that doesn’t behave in a very friendly manner.

Technorati Tags: Visual Studio,Regular Expressions

Creating Team Foundation Work Items With PowerShell

Lance Robinson — Wed, 26 Jan 2011 15:58:22 GMT

Here is the simple function I added to my powershell profile:

function create-tfstask ($desc) {
 tfpt workitem /new $workItemType /collection:$serverUrl /fields:"Title=$($desc);Assigned To=$assignee;AreaId=$areaId;IterationId=$iterationId"
}

To find the AreaId and IterationId for your project/versions, just look at a bug you know is setup correctly:

PS C:\> tfpt query /collection:http://3bs001vsteam:8080/tfs /wiql:"select AreaId,IterationId from workitems where ID = 879"

Next I hooked this into my existing "todo" function by adding a new case in its $target switch statement for “tfs”, which calls my create-tfstask function and returns. Updated todo function:

function todo {
  param([string] $target = "work",
        [string] $msg )
			
  $emailFrom = "lance@3birdsmarketing.com"
	
  #combine all the cmd line args into one "message"
  if ($args -ne "") {
    $msg = $msg + " " + $args
  }
	
  #what is the target of the message?
  switch ($target)
  {
    "work" { $target = "lance@3birdsmarketing.com" }
    "home" { $target = "lmrobins@gmail.com" }
    "tfs" { create-tfstask $msg; return }
  }	
	
  $subject = "Todo: " + $msg
  $body = $msg
  $smtpServer = "3bs001exch"	
  $smtp = new-object Net.Mail.SmtpClient($smtpServer, 25)
  $smtp.Send($emailFrom, $target, $subject, $body)
}

Technorati Tags: PowerShell,TFS,Team Foundation

How do I rollback a TFS check-in?

Lance Robinson — Tue, 21 Dec 2010 16:24:04 GMT

I can never remember how to rollback a check-in, and there all kinds of mess in search results about this (change between different versions of TFS etc), so I thought I’d just put this here so I won’t forget anymore. :) Thanks to @manningj, TFS genius.

Just drop to the command line and use tf.exe.

Example:

tf rollback /changeset:12345

For more on the tf.exe commands:

tf help

Technorati Tags: Visual Studio,Team Foundation,Rollback

PowerShell – Recycle All IIS App Pools

Lance Robinson — Thu, 16 Dec 2010 20:59:17 GMT

With a little help from Shay Levy’s post on Stack Overflow and the MSDN documentation, I added this handy function to my profile to automatically recycle all IIS app pools.

function Recycle-AppPools {
  
    param(
    [string] $server = "3bhs001",
    [int] $mode = 1, # ManagedPipelineModes: 0 = integrated, 1 = classic
    )  $iis = [adsi]"IIS://$server/W3SVC/AppPools"
 $iis.psbase.children | %{ 
   $pool = [adsi]($_.psbase.path); 
   if ($pool.AppPoolState -eq 2 -and $pool.ManagedPipelineMode -eq $mode) {
     # AppPoolStates:  1 = starting, 2 = started, 3 = stopping, 4 = stopped          
     $pool.psbase.invoke("recycle") 
     }
   }
}

Setting a Master Page Dynamically

Lance Robinson — Tue, 17 Aug 2010 19:04:10 GMT

To set an ASPNET master page dynamically, use the Page_PreInit function and set the Page.MasterPageFile property. For example:

protected void Page_PreInit(object sender, EventArgs e)
{
this.Page.MasterPageFile = "~/MasterPages/" + mymaster + ".Master";
}

In the above example, mymaster should be set by whatever your requirements dictate – read from DB/CMS/whatever. The page (aspx) itself shouldn’t have any other reference to the master page (ie, no “MasterPageFile attribute in the page directive), however it will still need the content placeholders, of course.

Technorati Tags: ASPNET

PowerShell TruncateAtWhitespace Function

Lance Robinson — Mon, 16 Aug 2010 19:30:13 GMT

Here’s a TruncateAtWhitespace function that takes an incoming parameter value and an incoming max length, and returns a substring broken at a whitespace position. This way if you have “Lance has a blog” and you need to truncate it to 8 characters or less, you get “Lance” instead of “Lance ha”.

function TruncateAtWhitespace{
    param(
        [string]$value,
        [int]$maxlength=200
    )
    $maxlength-=3; #allow for "..." suffix
    if ($value.Length -le $maxlength) {
      return ($value + "...");
    }
    $closestwhitespaceindex = [int]$value.Substring(0, $maxlength).LastIndexOf(" ");
    if ($closestwhitespaceindex -gt 0) {
      $value = $value.Substring(0, $closestwhitespaceindex) + "...";
    } else {
      $value = $value.Substring(0, $maxlength);
    }
    return $value;
}

Technorati Tags: PowerShell

CSharp TruncateAtWhitespace Function

Lance Robinson — Mon, 16 Aug 2010 19:28:56 GMT

    /// <summary>

    /// Truncate at the end of a word

    /// </summary>

    /// <param name="value">The original string</param>

    /// <param name="maxlength">The maximum length of string to return</param>

    /// <returns>A substring of the original, broken at the end of a word</returns>

    public static string TruncateAtWhitespace(string value, int maxlength)

    {

      maxlength = maxlength - 3; //allow for ending "..."

      if (value.Length <= maxlength) return value + "...";

      int closestwhitespaceindex = value.Substring(0, maxlength).LastIndexOf(" ");

      if (closestwhitespaceindex > 0)

      {

        value = value.Substring(0, closestwhitespaceindex) + "...";

      }

      else

      {

        value = value.Substring(0, maxlength);

      }

      return value;

    }

Technorati Tags: ASPNET,C#

Listing SPQuery FieldNameRefs

Lance Robinson — Mon, 07 Dec 2009 09:24:16 GMT

It took me a while to figure out how to get a list of all the available fields for a particular type of list in SharePoint (for performing custom queries in SPQuery). I was looking for a published list of these fields, which as far as I know does not exist. Instead, you just use the GetList method of the Lists SOAP service. Here’s an example SOAP request:

<?xml version="1.0" encoding="utf-8"?> 
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> 
  <SOAP-ENV:Body> 
    <GetList xmlns="http://schemas.microsoft.com/sharepoint/soap/"> 
      <listName>Private Documents</listName> 
    </GetList> 
  </SOAP-ENV:Body> 
</SOAP-ENV:Envelope>

Just specify the name of the list you want the fields for as the value for the listName input element.

One easy way to work with SharePoint services remotely is by using /n software’s SharePoint Integrator developer toolkit. Using its SPSite component in Visual Studio I can whip together a few lines of code to consume get the results from the aforementioned service:

spsite1.URL = "http://mysharepoint/mysite/";
spsite1.User = "DOMAIN\lancer";  
spsite1.Password = "password";  
spsite1.DescribeList("Private SharePoint Documents");;

/n software SharePoint Integrator highlights:

Read, Write, and Create SharePoint Lists Items, Documents, and Attachments.
Programmatic control of SharePoint Sites, capabilities, and configuration
128-bit strong SSL encryption keeps sensitive transaction information confidential.
Small and lightweight components with no dependencies on external libraries.
Native development components for all supported platforms and component technologies.
Unlimited free Email technical support backed by an experienced & professional staff.
Compatible with Microsoft Office SharePoint Server (MOSS), and Windows SharePoint Services v3.0 + (WSS).

Technorati Tags: SPQuery,SharePoint

How to embed Excel in a .NET WinForms App

Lance Robinson — Thu, 17 Sep 2009 13:19:35 GMT

Download and install owc11.
Run AxImp on OWC11.dll, which will have been installed in the microsoft shared\web components directory (ie C:\Program Files\Common Files\microsoft shared\Web Components\11\). AxImp.exe can be found in the Windows SDK (ie, C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bin\AxImp.exe).
In Visual Studio project, drag OWC11.dll to a toolbox tab and drop the Excel component on form.

Voila. When it comes deployment time, you’ll need the AxInterop.OWC11.dll.

Some sample code:

Set a specific cell value:
Spreadsheet1.Cells.get_Item(row, col).set_Value(System.Reflection.Missing.Value, "BSXBW2183NN");

Get the string value of a specific cell:
Spreadsheet1.Cells.get_Item(row, col).get_Value(System.Reflection.Missing.Value).ToString()
or
Spreadsheet1.Cells.get_Item(i, 1).Text.ToString();

Set the background color of a row:
Object ob = "#66FF66";
Spreadsheet1.Rows.get_Item(row, System.Reflection.Missing.Value).Font.set_Color(ref ob);

Technorati Tags: Excel,.NET