Archive for the ‘.NET ORM’ Category
Posted by jpluimers on 2018/11/27
Since I am going to be involved with building some REST API servers and clients in .NET, here are some links to get me up to speed.
Posted in .NET, .NET ORM, ASP.NET, C#, Development, EF Entity Framework, NHibernate, Software Development | Leave a Comment »
Posted by jpluimers on 2016/03/22
Even though as of 12c R1, Oracle supports a row limiting clause, NHibernate 4.2 with Oracle.DataAccess.dll 2.112.3.0 does not support that.
When you let it generate the SQL for a LINQ Take call to limit the number of results, you get an exception like this (full exception and stack trace are below):
System.NotSupportedException was unhandled by user code
HResult=-2146233067
Message=Specified method is not supported.
The place where you Take is important, as this does fail:
Read the rest of this entry »
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, .NET ORM, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, C# 6 (Roslyn), Database Development, Development, NHibernate, OracleDB, Software Development | Leave a Comment »
Posted by jpluimers on 2016/03/17
When you have one app.config for your whole set of DTAP environments (develop/test/acceptance production), every once in a while you get this error:
ORA-12154: TNS:could not resolve the connect identifier specified
For this particular setup, it means the replacement of parameters in the app.config with actual values from the DTAP went wrong (or was missing). For that we’ve some steps in both the PreBuildEvent and PostBuildEvent of the .csproj file:
PreBuildEvent:
del "$(ProjectDir)$(TargetFileName).config"
copy "$(ProjectDir)app.config" "$(ProjectDir)$(TargetFileName).config"
PostBuildEvent:
powershell -noprofile -file Replace-Parameter.ps1 -Path "$(TargetDir)$(TargetFileName).config"
The PreBuildEvent looks like it is not needed, but sometimes Visual Studio forgets to perform the copy action.
–jeroen
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, .NET ORM, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, C# 6 (Roslyn), Database Development, Development, NHibernate, OracleDB, Software Development | Leave a Comment »
Posted by jpluimers on 2012/08/15
A few weeks ago, Bill Karwin did a must watch webinar on the prevention SQL Injection titled “SQL Injection Myths and Fallacies“.
Bill Karwin (twitter, new blog, old blog, Amazon) is famous for much work in the SQL database community, including InterBase/Firebird, mySQL, Oracle and many more.
He also:
Anyway, his webinar is awesome. Be sure to get the slides, watch the replay, and read the questions follow up.
Watching it you’ll get a better understanding of defending against SQL injection.
A few very valuable points he made: Read the rest of this entry »
Posted in .NET, .NET 3.5, .NET 4.5, .NET ORM, ASP.NET, Batch-Files, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, C++, Cloud Development, COBOL, CommandLine, Database Development, Delphi, Delphi for PHP, Delphi x64, Delphi XE2, Development, EF Entity Framework, F#, Firebird, FireMonkey, History, InterBase, iSeries, Java, JavaScript/ECMAScript, Jet OLE DB, LINQ, LLBLGen, MEF, Microsoft Surface, Mobile Development, PHP, PowerShell, Prism, Scripting, SharePoint, SilverLight, Software Development, SQL, SQL Server, SQL Server 2000, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, SQL Server 7, VB.NET, VBS, Visual Studio 11, Visual Studio 2002, Visual Studio 2003, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio and tools, Web Development, Windows Azure, WinForms, WPF, XAML, xCode/Mac/iPad/iPhone/iOS/cocoa | 1 Comment »
Posted by jpluimers on 2012/05/23
Yes. Dorothy. There are people using the ADO .NET Entity Framework with SQL Server 2000 in parallel of moving towards a more modern Microsoft SQL Server version.
Entity Framework is lovely for developing data-centric applications.
By default, Visual Studio 2010 will target SQL Server 2008 as a database. That is fine, but it is kind of invisible it does: there is no property or dialog where you can change this.
What you have to change in order to have the Entity Framework send SQL Server 2000 compatible queries is to:
- Right click your .edmx file
- Choose “Open with”
- Choose the “XML (text) editor”
- Find the ProviderManifestToken attribute
- Change the value (usually from “2008”) into “2000”
- Save the .edmx file
- Build and run your application
A few caveats:
Read the rest of this entry »
Posted in .NET, .NET ORM, C#, C# 2.0, C# 3.0, C# 4.0, Development, EF Entity Framework, Software Development, SQL Server, SQL Server 2000, SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 | Leave a Comment »
Posted by jpluimers on 2011/09/13
Almost a year ago there was a post on the MSDN forums titled EF4 – update model from database ignores some changes.
These are the changes it ignores that I found so far:
- Column renames
- Column data type changes
- Changed foreign key relations
Have you found others?
Which EF versions are worse/better in this respect?
Note that the EF support in Visual Studio 2010 does not warn you if the the model is incompatible with your database.
You will get errors like this at run-time:
Read the rest of this entry »
Posted in .NET, .NET ORM, Database Development, Development, EF Entity Framework, Software Development | 2 Comments »
Posted by jpluimers on 2011/09/06
The drawback of using ORM layers is that often the error messages are very cryptic, and it takes some getting used to in order to find the (often deceptively) simple solution.
This case was an Entity Framework wrapper around a SQL Server database where the primary and foreign keys were all GUIDs, and some of the foreign keys were optional.
So the generated model has a mixed use of Guid? and Guid data types.
Below is the full stack trace, but here is the exception class and message:
System.NotSupportedException: Unable to create a constant value of type ‘System.Object’. Only primitive types (‘such as Int32, String, and Guid’) are supported in this context.
The exception is caused by a piece of code like this:
public static long CountChildren(ParentEntity parentEntity)
{
using (EntitiesObjectContext objectContext = new EntitiesObjectContext())
{
Guid? parentId = parentEntity.ID;
if (null == parentId)
throw new ArgumentNullException("parentEntity.Id");
IQueryable<ChildEntity> ChildEntitys =
from content in objectContext.ChildEntity
where content.ParentID.Equals(parentId)
select content;
long result = ChildEntitys.Count(); // BOOM!
return result;
}
}
The stack trace at the end of this post contains a truckload of ExpressionConverter lines. Since the LINQ expression contained only one WHERE clause, the mentioning of the list of primitive types in the message (Int32, String, and Guid) made me change the code into the one below.
Read the rest of this entry »
Posted in .NET, .NET ORM, C#, Development, EF Entity Framework, Software Development | 5 Comments »
Posted by jpluimers on 2011/05/25
I love the Entity Framework, but as with every layer of abstraction, sometimes you need to get underneath in order to solve problems.
For EF questions, I usually browse the presentations, blog, articles or Entity Framework book from Julie Lerman.
I met her first at an SDC conference years ago: she has a great way of explaining new concepts in an easy to grasp way, not being afraid to do a deep dive into technology when needed.
Her article MSDN Magazine: Data Points – Profiling Database Activity in the Entity Framework is a great way to start digging for the actual SQL being executed by EF on your behalf.
It has a balanced list of ways to get that SQL, and describes the pros and cons for each means.
The comments point you to some more ways.
Recommended reading!
–jeroen
Posted in .NET, Development, EF Entity Framework, Software Development | Leave a Comment »
Posted by jpluimers on 2011/05/05
The Entity Framework needs you to have a connection string in your App.Config.
It is good practice having your Entity Framework model in a separate assembly.
When using it in your main app, be aware that the connection string that belongs to your model needs to be in the App.config of your main app.
If not, you get an exception like this:
System.ArgumentException was unhandled
Message=The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid.
Source=System.Data.Entity
StackTrace:
at System.Data.EntityClient.EntityConnection.ChangeConnectionString(String newConnectionString)
at System.Data.EntityClient.EntityConnection..ctor(String connectionString)
at System.Data.Objects.ObjectContext.CreateEntityConnection(String connectionString)
at System.Data.Objects.ObjectContext..ctor(String connectionString, String defaultContainerName)
The clue is the contents of the defaultContainerName parameter: you will see that in the App.config of your Entity Framework assembly.
Copy that over to the App.config of your main assembly, then make sure it points to your right database (if you use OTAP), then go :-)
Your App.config then looks like this:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<connectionStrings>
<add name="MyEntities" connectionString="metadata=res://*/My_EntityModel.csdl|res://*/My_EntityModel.ssdl|res://*/My_EntityModel.msl;provider=System.Data.SqlClient;provider connection string="data source=my-sql-server;initial catalog=my-database;persist security info=True;user id=my-user;password=my-password;multipleactiveresultsets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
</connectionStrings>
</configuration>
–jeroen
Posted in .NET, C#, Database Development, Development, EF Entity Framework, Software Development, SQL Server | Leave a Comment »
The Wiert Corner - irregular stream of stuff 