var a = from address in dc.Addresses
select new {
ID = address.AddressID,
Address1 = address.AddressLine1,
Address2 = address.AddressLine2,
};
var b = from address in dc.Addresses
select new {
ID = address.AddressID,
Address1 = address.AddressLine1,
Address2 = address.AddressLine1, // notice AddressLine1 repeated
};
var q = a.Take(10).Union (b.Take(10));
q.ToArray ();

SqlException: All the queries in a query expression containing a UNION operator must have the same number of expressions in their select lists.

SELECT [t2].[AddressID] AS [ID], [t2].[AddressLine1] AS [Address1], [t2].[AddressLine2] AS [Address2]
FROM (
SELECT TOP (10) [t0].[AddressID], [t0].[AddressLine1], [t0].[AddressLine2]
FROM [Person].[Address] AS [t0]
UNION
SELECT TOP (10) [t1].[AddressID], [t1].[AddressLine1]
FROM [Person].[Address] AS [t1]
) AS [t2]

Notice the third SELECT statement is only selecting two columns instead of the required three.

Please rate and validate this bug at the MSDN Microsoft Product Feedback Center so Microsoft responds with a solution or workaround.

[Column(Storage="_ProductLine", DbType="NChar(2)")]
public string ProductLine
{
  get
  {
    return this._ProductLine;
  }
  set
  {
    if ((this._ProductLine != value)) {
      this.OnProductLineChanging(value);
      this.SendPropertyChanging();
      this._ProductLine = value;
      this.SendPropertyChanged("ProductLine");
      this.OnProductLineChanged();
    }
  }
}

The odd code involves the SendPropertyChanging() method call. This method call should pass the name of the property, just like the SendPropertyChanged() method call, according to the documentation. Another interesting detail: The OnProductLineChanging and OnProductLineChanged partial method calls are out of order:

1. Call OnProductLineChanging() partial method
2. Raise PropertyChanging event, but don’t tell which property is changing – send an empty string instead
3. Set the property’s field’s value to the specified new value
4. Raise PropertyChanged event and specify which property is changing
5. Call OnProductLineChanged() partial method

Why is the PropertyChanged event raised before calling the OnProductLineChanged partial method?

All classes created by LINQ to SQL add the following protected methods:

protected virtual void SendPropertyChanging() {
  if ((this.PropertyChanging != null)) {
    this.PropertyChanging(this, emptyChangingEventArgs);
  }
}
protected virtual void SendPropertyChanged(String propertyName) {
  if ((this.PropertyChanged != null)) {
    this.PropertyChanged(this,
        new PropertyChangedEventArgs(propertyName));
  }
}

Again, what’s odd about this code is how the SendPropertyChanging() method does not have a property name parameter and sends a emptyChangingEventArgs field reference to the PropertyChanging event rather than creating a new instance of the EventArgs like the SendPropertyChanged() method call does. By creating a new instance of the EventArgs in SendPropertyChanged, it’s able to pass the property name in the constructor (like the documentation says it should).

Here is the field that is passed to all invocations of the event:

private static PropertyChangingEventArgs emptyChangingEventArgs =
  new PropertyChangingEventArgs(String.Empty);

As you can see from this constructor, the property that is changing is an empty string. Given the fact that this is a private field and should not be modified by extension methods, it’s odd that this field is not static readonly.

My guess is that the code is generated incorrectly to account for a data-binding or allocation problem. I’ve come to this conclusion by the emptyChangingEventArgs field – it reduces the object instance creation in half for each property change when there are event consumers for the changing event. The big disadvantage for event consumers is that they doesn’t know which property is changing on an object instance.

One alternative is to use PLINQO, which creates the properties correctly.

UPDATE: I have found that this has already been reported. Unfortunately, Microsoft has closed this bug and said it was by design, even though the generated code does not follow Microsoft’s documentation for the PropertyChangingEventArgs class.

To reproduce this bug, create this stored procedure and run SqlMetal against it:
CREATE PROCEDURE [dbo].[ThisProcedureWillCauseSqlMetalToCrash] AS
BEGIN
SET NOCOUNT ON;
SELECT 1 [A], 2 [ ], 3 [C]
END

Applies to:

• Visual Studio 2008 RTM
• Microsoft Windows SDK v6.0A

Please rate and validate this problem at the MSDN Microsoft Product Feedback Center so Microsoft responds with a solution or workaround.

In Microsoft. Practices. EnterpriseLibrary. Logging. TraceListeners. EntLibLoggingProxyTraceListener, comment out
properties.Add(TraceEventCacheKey, eventCache); // line 66 & 146 (fix for SerializationException)
In Microsoft. Practices. EnterpriseLibrary. Logging. TraceListeners. MsmqTraceListener, change queueMessage.Label = messageLabel;
to queueMessage.Label = string.IsNullOrEmpty (messageLabel) ? string.Empty : messageLabel; // line 153 (fix for ArgumentNullException)
In LoggingDatabase.sql, change [Title] [nvarchar](256) NOT NULL,
to [Title] [nvarchar](256) NULL,

HttpWebRequest request = …;
request.CachePolicy =
  new System.Net.Cache.HttpRequestCachePolicy (
    System.Net.Cache.HttpRequestCacheLevel.Default);
request.GetResponse ();

GetResponse () throws a WebException: “The request was aborted: The request was canceled.” Inner exception shows that the private method CheckCacheUpdateOnResponse () of System.Net.HttpWebRequest encounters a NullReferenceException.

A “workaround” would involve loading the user’s profile. For example, if the application pool custom identity is DOMAIN\MyWebApp, log in to the server as MyWebApp. The error goes away – until the profile is unloaded.

This problem does not occur when the web application is using the default application pool identity, NetworkService, because I believe that profile is already loaded by default.

Another bug report is somewhat similar to this but only manifests after a few thousand requests. These are probably symptoms of a much larger bug (or design flaw – http request caching is currently implemented through IE’s cache).

Update: Microsoft has reproduced this bug and will be addressing it in a future release.

• Syntax error in manifest or policy file file name on line 2. The manifest file root element must be assembly.
• The application failed to launch because of an invalid manifest.
• Generate Activation Context failed for file name.Manifest. Reference error message: The operation completed successfully.

You may also receive this message box:

• The operation could not be completed. This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem.

If you were using a beta version of Visual Studio 2005, you may have the configuration namespace, http://schemas.microsoft.com/.NetConfiguration/v2.0, referenced in your app.config. This is not supported by SxS, so you application will fail to load when you create an application manifest, or attempt to use ClickOnce.

Please rate and validate this problem at the MSDN Microsoft Product Feedback Center so Microsoft responds with a solution or workaround.

• The manifest may not be valid or the file could not be opened
• Manifest XML signature is not valid
• The profile for the user is a temporary profile

Please rate and validate this problem at the MSDN Microsoft Product Feedback Center so Microsoft responds with a solution or workaround.