Using Entity Framework-based Repository Pattern in MVC Causes Errors

Using Entity Framework 4.0 in an MVC 3.0 application using the repository pattern where the data model is created in a separate project can result in compilation errors generated when the view are requested. Basically the views fail to compile properly if the view's model is an IEnumerable type of an entity object.

The compiler error message is not very helpful (though it gives hints)

Compiler Error Message: BC30456: 'Title' is not a member of 'ASP.views_

This indicates that the View object failed to compile all together and this only happens when the Entity Framework generated objects are involved in the model of the View.

Line 1:  <%@ Page Title="" Language="VB" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage(Of IEnumerable (Of WebApp.Domain.MyModelObject))" %>

One way to force the compiler to give a better message is to have the view accept a generic object and then later in the view code cast the object to what it really is (in this case an IEnumerable (Of WebApp.Domain.MyModelObject)

So the new Page directive looks like

<%@ Page Title="" Language="VB" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage(Of Object)" %>

And now instead of using Model right away, we have to cast it to its actual type

<% Dim modelData = CType(Me.Model , IEnumerable(Of WebApp.Domain.MyModelObject)) %>


Doing the above changes causes the compiler to give a better message because it's now able to compile the view but at run-time it finds that there are missing assemblies (the message below explains it)

Compiler Error Message: BC30007: Reference required to assembly 'System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' containing the base class 'System.Data.Objects.DataClasses.EntityObject'. Add one to your project.

And the guilty line that caused the error as you might have expected is

<% Dim modelData = CType(Me.Model , IEnumerable(Of WebApp.Domain.MyModelObject ))  %>

And now it's obvious that we need to add the references to our web.config (system.web -> compilation -> assemblies)

<add assembly ="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>

There are other reasons why this error might come up which may not have to do with Entity Framework

look here for more http://stackoverflow.com/questions/1545538/asp-net-error-bc30456-title-is-not-a-member-of-asp-views-controllername-view

Sequential Numbering of Group of Events with T-SQL

An example to illustrate the title is winning and losing streaks in a football game. Suppose we have the below set of data about a number of a series games.

mnum	match_date	result
1	07/01/2011	L[oss]
2	07/02/2011	L
3	07/03/2011	W[in]
4	07/04/2011	W
5	07/05/2011	L
6	07/06/2011	W
7	07/07/2011	W

The goal is to sequentially number each losing or winning streak. So for the above example, the number would look like the below:

mnum	match_date	result	streak
1	07/01/2011	L	-1
2	07/02/2011	L	-2
3	07/03/2011	W	1
4	07/04/2011	W	2
5	07/05/2011	L	-1
6	07/06/2011	W	1
7	07/07/2011	W	2

We chose to number the two events in two different directions (negative for losses and positive for wins) . Below is an approach I took a while ago (and needed recently) using T-SQL to solve this problem:

First let's create a temporary table (a table variable) that adds the streak column. To do this we basically self-join the table so that each game is compared to the following game. The streak is then 1 if two consecutive games have different results (W/L or L/W). If, however, two consecutive games have the same result we use row_number() ranking function to denote the streak number. We do this operation once for the losses and once for the wins as the code illustrates below

declare @temp_results table(row_num int,match_date datetime,result char(1),streak int);
insert into @temp_results (row_num,match_date,result,streak)
select row_number() over (order by match_date) as row_num, match_date,result,streak
from(
select m1.match_date,m1.result
,(case when m1.result = m2.result then row_number() over(order by m1.match_date) else 1 end)
as streak
from @matches m1 left join @matches m2
on m1.mnum = m2.mnum+1
where m1.result= 'W'
UNION ALL
select m1.match_date,m1.result
,(case when m1.result = m2.result then -1 * (row_number() over(order by m1.match_date)) else -1 end )
as streak
from @matches m1 left join @matches m2
on m1.mnum = m2.mnum+1
where m1.result= 'L'
) as chld

The above code is not enough because row_number will not generate sequential streaks. In fact the data so far looks like the table below

mnum	match_date	result	streak
1	07/01/2011	L	-1
2	07/02/2011	L	-2
3	07/03/2011	W	1
4	07/04/2011	W	2
5	07/05/2011	L	-1
6	07/06/2011	W	1
7	07/07/2011	W	4

The second step is to get rid of the gaps between sequence numbers. To do this we update the table (the table variable) so that for each streak if it's not 1 or -1 we find the last game (max) that has the same result as the current place but it took place before the current game and then subtract that game's row_number for current row_number. Code explains it better:

-- we need this update as a fix to get rid of the gaps between successive wins or successive losses
update t1
set t1.streak =
(case when t1.result = 'W' then 1+t1.row_num - (select max(row_num)
from @temp_results t
where t.streak = 1
and t.row_num < t1.row_num ) else -1 * (1+t1.row_num - (select max(row_num) from @temp_results t where t.streak = -1 and t.row_num < t1.row_num )) end) from @temp_results t1 --left join @temp_results t2 on t1.row_num = t2.row_num where t1.streak not in (1,-1)

Report Rendering Fails in Local Mode

A desktop program developed using .NET 3.5 framework and was using RDLC report in local mode and a ReportViewer control  was throwing what might seem a weird exception the exception looked something like the below

The definition of the report 'Main Report' is invalid. 

Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: 

An unexpected error occurred in Report Processing. 

System.UnauthorizedAccessException: Access to the path 'C:\Documents and Settings\\Local Settings\Temp\expression_host_05cd5e1af4624646bc2dd846b60460f0.dll' is denied.

What is this expression_host_....dll file and Why is The Report Rendering Engine Trying to Access It?

When you write an expression in your report definition (any expression even something that looks like =Fields!FirstName.Value + " " + Fields!LastName.Value) or when you use Custom Code, the report rendering engine does two things; it seems to me. One the rendering engine extracts all custom expressions and custom code and, based on these custom expressions and code, it dynamically creates VB.NET classes which are then compiled on the fly to a .NET assembly. These files and the resulting assembly are placed in the %TEMP% directory; they are deleted once they are no longer needed by the current instance of the running report. The second thing the rendering engine does is referencing the dynamically created assembly (which is named expression_host_.dll) when rending your report and making the necessary calls to this assembly as dictated by your report definition. 

How is The Above Explanation Related to The Error In Question?


Some anti-malware/anti-virus software do not like programs creating dynamic DLLs, it seems. In my case I verified that the dynamically created assembly was indeed blocked by the anti-malware program so that the ReportViewer and the hosting application could not use it and the even rendering engine program could not delete the expression_host dll file; which it normally does once the report is done rendering.

As soon as stopped the anti-malware program or just told to trust certain pattern of files, the report rendered perfectly without a problem.

Finally, it's worth mentioning that this problem was sporadic and had no predictable pattern. That is, one out 20 trials  the report would render fine but most of the time it fails. Something which leads to believe that there was a "race" between the report rendering engine and its application and the anti-malware program. Sometimes the anti-malware program would miss the host_expression dll and the report would render fine but most of the time the dll files is blocked.

The Bottom Line:


If you're running a program that use a RLDC report in local mode and the report uses expressions and custom code, rendering the report could fail due to an anti-virus/ anti-malware program blocking the custom assembly created to host your expressions and/or custom code.

Renaming Excel Sheets Exported from Reporting Services 2005 via an Excel Add-In

Intro

When a Reporting Services 2005 report with multiple pages is exported to excel to creates an excel document with multiple sheets where the first sheet is an index sheet or document map and the remaining sheets are report pages. Reporting Services 2005 gives these sheets generic names Sheetxy. Unlike the situation with Reporting Services 2008 [R2] there's no straight forward way of telling Reporting Services 2005 how name the report pages. One way to rename this sheets in excel to match the entries in the document map (which are more meaningful than sheetXY) is through an excel add-in. Below is an Excel add-in written in VB to rename sheets based on the document map. The code is tested on Windows XP/7 with Office 2003 Professional/Basic. If you decide to use the code below, make sure it has no unwanted side-effects in your environment and make sure you test it.

The basic idea of the code is:

• Each document map entry points to a named range (which is stored in the built-in array Names
• Using the range name we can find out the sheet that's being pointed to by an entry in the document map
• Once the sheet is found, its name is changed to that of the hyperlink's DisplayText property of the pointing document map entry.
  

Steps to Create Excel Add-In using VBA

1. Open a new excel workbook and go to the Visual Basic Editor
2. In the left pane, right-click on VBAProjects (Book1) and Insert -> module. This module will have the code that will rename the sheets. The code in this module will be called when the custom menu item is clicked.
3. This code does the renaming (you can paste in the newly created module
   

   Private Const INVALID_CHARS As String = "[]*/\?:"
   Private Const SHEET_NAME_MAX_LENGTH As Integer = 31
   Private Const DOCMAP_SHEET_NAME As String = "document map"
   Private Const DOCMAP_SHEET_NEW_NAME As String = "__INDEX__"
   Public Sub RunRenameSheetsCode()
       If Not Application.ActiveWorkbook Is Nothing Then
           Call RenameSheets(Application.ActiveWorkbook)
       End If
   End Sub
   Public Sub RenameSheets(ByRef wb As Workbook)
       On Error GoTo Error
       Dim sh As Worksheet
       Dim row As Integer
       Dim cell As Range
       Dim newName As String
       row = 1
       If Not IsFirstSheetDocMap(wb) Then
           Exit Sub
       End If
       Do While True
           Set cell = wb.Sheets(1).Range("$A$" & CStr(row))
           If Len(cell.Value) <= 0 Then
               Exit Do
           End If
           If cell.Hyperlinks.Count > 0 Then
               Set sh = GetSheetByRangeName(wb, cell.Hyperlinks(1).SubAddress)
               If Not sh Is Nothing Then
                   newName = CleanSheetName(cell.Value)
                   sh.name = newName
               End If
           End If
           row = row + 1
       Loop
       wb.Worksheets(1).name = DOCMAP_SHEET_NEW_NAME
       Exit Sub
   Error:
        MsgBox ("An error occurred while trying to rename sheets")
   End Sub
   Public Function CleanSheetName(ByVal name As String)
       Dim newName As String
       newName = name
       For i = 1 To Len(INVALID_CHARS)
          newName = Replace(newName, Mid(INVALID_CHARS, i, 1), "")
       Next
       newName = Left(newName, SHEET_NAME_MAX_LENGTH)
       CleanSheetName = newName
   End Function
   Public Function GetSheetByRangeName(ByRef wb As Workbook, rangeName As String) As Worksheet
       Dim i As Integer
       Dim sheetName As String
       Dim charIndex As Integer
       For i = 1 To wb.Names.Count
       If wb.Names(i).name = rangeName Then
           sheetName = wb.Names(i).RefersTo
           charIndex = InStr(1, sheetName, "!")
           If charIndex > 0 Then
               sheetName = Left(sheetName, charIndex - 1)
               sheetName = Right(sheetName, Len(sheetName) - 1)
               Exit For
           End If
       End If
       Next
       charIndex = InStr(1, sheetName, "'")
       If charIndex > 0 Then
           sheetName = Right(Left(sheetName, Len(sheetName) - 1), Len(sheetName) - 2)
       End If
       If Len(sheetName) > 0 Then
           Set GetSheetByRangeName = wb.Sheets(sheetName)
       End If
   End Function
   Public Function IsFirstSheetDocMap(ByRef wb As Workbook) As Boolean
       If wb.Worksheets.Count > 0 Then
           If LCase(wb.Worksheets(1).name) = DOCMAP_SHEET_NAME Then
               IsFirstSheetDocMap = True
               Exit Function
           End If
       End If
       IsFirstSheetDocMap = False
   End Function
   
   
     

4. Go back to the left pane and expand VBAProjects and also expand Microsoft Excel Objects and double click the ThisWorkBook node . The ThisWorkBook will host the code responsible for creating the custom menu and hooking the OnAction event to the code responsible for renaming the sheets.
   

   Private Const MENU_CAPTION As String = "&Custom Menu"
   Private Const MENU_ITEM_CAPTION As String = "&Rename Sheets"
   Private Sub AddMenus()
   'ResetMenuBar
    On Error Resume Next
    Me.Application.CommandBars("Worksheet Menu Bar").Controls(MENU_CAPTION).Delete
    Dim mainMenu As CommandBar
    Dim customMenu As CommandBarControl
    Dim customMenuItem As CommandBarButton
    Dim helpMenuIndex As Integer
    Set mainMenu = Me.Application.CommandBars("Worksheet Menu Bar")
    helpMenuIndex = mainMenu.Controls("Help").Index
    Set customMenu = mainMenu.Controls.Add(Type:=msoControlPopup, Before:=helpMenuIndex)
    customMenu.Caption = MENU_CAPTION
    Set customMenuItem = customMenu.Controls.Add(Type:=msoControlButton)
    customMenuItem.Caption = MENU_ITEM_CAPTION
    customMenuItem.OnAction = "RunRenameSheetsCode"
   End Sub
   Private Sub ResetMenuBar()
       Application.CommandBars("Worksheet Menu Bar").Reset
   End Sub
   Private Sub Workbook_Open()
       Call AddMenus
   End Sub
   

5. Save the current workbook as an excel add-in. From File menu select save as and in the save-as dialog in the "Save as type" list find and select Microsoft Office Excel Add-in (*.xla).
   By default excel saves new addins in the add-ins folder designated for the current user which is %USERPROFILE%\Application Data\Microsoft\AddIns. You can also place the add-in in C:\Program Files\Microsoft Office\OFFICE11\XLSTART causes excel to load your add-in when excel is started regardless of the user who started excel.
   
6. Every time you start excel now you'll see your custom menu. If you the first sheet is name "document map" and the user clicks on the menu item which we created to rename sheets, the add-in will attempt renaming sheets based on what's in the document map.

Reporting Services Exception: Execution cannot be found

The rsExceutionNotFound Problem:

On an instance of SQL Server Reporting Services 2005 I noticed for a good while that the service is throwing rsExecutionNotFound exception and logging those as warnings to Windows application event log. A typical warning may look like


Event Type: Warning
Event Source: ASP.NET 2.0.50727.0
Event Category: Web Event
Event ID: 1309
Date:
Time:
User:
Computer: SERVERNAME
Description:
Event code: 3005
Event message: An unhandled exception has occurred.
Event time:
Event time
Event ID: 5be391324153445f9e5e3ace93334c55
Event sequence: 38
Event occurrence: 1
Event detail code: 0

Application information:
    Application domain: /LM/W3SVC/1/Root/Reports-1-129490022321612580
    Trust level: RosettaMgr
    Application Virtual Path: /Reports
    Application Path: ...\Reporting Services\ReportManager\
    Machine name: SERVERNAME

Process information:
    Process ID:
    Process name: w3wp.exe
    Account name:

Exception information:
    Exception type: ReportServerException
    Exception message: Execution '<SESSION ID>' cannot be found (rsExecutionNotFound)

Request information:
    Request URL: http://SERVERNAME/Reports/Reserved.ReportViewerWebControl.axd?ReportSession=SessionID really long URL
    Request path: %21 {I guess these %numbers are supposed to substituted }
    User host address: %22
    User: %23
    Is authenticated: %24
    Authentication Type: %25
    Thread account name: %26

After some searching I found this blog entry http://blogs.msdn.com/b/jgalla/archive/2006/10/11/session-timeout-during-execution.aspx. But the problem described in the mentioned blog is different and the suggested solution does not work in the cases I am describing here. The problem here is not that the report execution takes too long that the reporting services session times out.

The Cause of the Exception:

After some tracking and playing around I can say with a very high degree of certainty that the cause of the problem is  Internet Explorer [8]'s way of saving URLs when a user bookmarks (adds to favorites) a report's reporting services' URL.


I noticed that the exception (rsExecutionNotFound) is always thrown and the warning is logged in Windows when the user requests a report via a click on a favorite's URL. Of course the exception won't be thrown if the user visits the bookmarked report before its Reporting Services session expires. But typically with bookmarks they're visited days after the sessions are deleted and will for sure causes an rsExecutionException to be thrown.

If you look at an Internet Explorer 8 favorites shortcut file (*.url) you'll see some addition information saved along side the base URL of the bookmarked page. I believe this additional information is saved because when the report is rendered in the browser the page typically contains many iframes so the IE save their URLs as well. And in this case the additional information includes the Reporting Services SessionID. So when the user clicks on the favorite report, IE does try to make requests with old Reporting Services SessionIDs.

Here's a snippet of *.url file


[DEFAULT]
BASEURL=http://SERVERNAME/Reports/Pages/Report.aspx?ItemPath=/some/report/here
[DOC_ctl140TouchSession0]
BASEURL=http://SERVERNAME/Reports/Reserved.ReportViewerWebControl.axd?ReportSession=SessionID really long URL {the same shown in event log}
ORIGURL=javascript:''
[DOC_ctl140_ctl00_ctl03_ctl01]
....


A Solution:


Luckily if the cause of the exception is what I described here the user does not see on their screens and the exception itself is nothing serious although it might be bothersome to see those warnings in the events log. So in reality it does not affect the user's experience.

If the cause of the exception is that fact that the report takes tremendously long time to run to the point its session on Reporting Services times out, then the above mentioned link offers an easy solution.

SharePoint: The List That is Referenced Here no Longer Exists

While updating list items in a SharePoint list using the SharePoint web service API and specifically through calling
UpdateListItems method you may get everything setup correctly (authentication, authorization, retrieving the list using GetListItems etc.) but when you attempt to update the list using the API your updates are not reflected in the list and when poking around the returned object from UpdateListItems you'll notice it contains the detailed error message "The list that is referenced here no longer exists."

If that's the case make sure you are referencing the correct subsite and not the main site when you create the web reference to Lists.asmx web service. Alternatively you could set the Url property programmetically.

Here is an example:

If your site URL is http://my_share_point_site, the list.asmx can be found at http://my_share_point_site/sites/main/_vti_bin/lists.asmx?WSDL and you could use that URL to reference the API and some things might work. When you attempt to update a list found under some sub_site, your updates will silently fail. You have to reference http://my_share_point_site/sites/main/sub_site/_vti_bin/lists.asmx?WSDL for updates to your.

Some code:

string fieldName = "SomeListFieldToUpdate";
 SPLists.Lists listService = new Lists();
 listService.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
 listService.Url = "http://my_share_point_site/sites/main/sub_site/_vti_bin/lists.asmx?WSDL";
 /* setting Url not required except you referenced a different sub_site or the main site when 
 you created your web reference to Lists.asmx */
 XmlDocument batchDoc = new XmlDocument();
 XmlElement batchElement = batchDoc.CreateElement("Batch", "http://schemas.microsoft.com/sharepoint/soap/");
 batchElement.SetAttribute("OnError", "Continue");
 batchElement.SetAttribute("ListVersion", "21");
 batchElement.SetAttribute("ViewName", editListViewGUID);
 string xml = string.Format(@"        
   {0}        
   {2}
   ", ID, fieldName, fieldValue);
 batchElement.InnerXml = xml;
 var result = listService.UpdateListItems(listGUID, batchElement);
 int.TryParse(result.FirstChild.FirstChild.InnerText, out errorCode);
 return errorCode;

Equals vs IEquatable

IEquatable is not a replacement of Object.Equals. If your object implements IEquatable<T> it still HAS TO override Equals and GetHashCode http://blogs.msdn.com/b/jaredpar/archive/2009/01/15/if-you-implement-iequatable-t-you-still-must-override-object-s-equals-and-gethashcode.aspx 


Here is how the MSDN docs puts it:

If you implement IEquatable<T>, you should also override the base class implementations of Object.Equals(Object) and GetHashCode so that their behavior is consistent with that of the IEquatable<T>.Equals method. If you do override Object.Equals(Object), your overridden implementation is also called in calls to the static Equals(System.Object, System.Object) method on your class. This ensures that all invocations of the Equals method return consistent results. http://msdn.microsoft.com/en-us/library/ms131187.aspx