EF

Fixing error “No Entity Framework provider found for the ADO.NET provider with invariant name ‘System.Data.SqlClient'”

No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlClient'

This post describes the fix to error “No Entity Framework provider found for the ADO.NET provider with invariant name ‘System.Data.SqlClient'”, which Visual Studio throws at your face when you try to run an application on any Windows-based system (or which you’ve dug out of event logs). Also, you’re probably using Entity Framework in your project.

Error

When debugging/running your code you get an error like this:

The running of the program is stopped there, and removing and readding the nuget packages and/or other references to dlls does not help. I, at least, tried also making all kinds of changes to my web.config and ran iisreset a couple of times, but nothing seemed to help. There’s a simple fix available, though!

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Applying Entity Framework’s Code-First Migrations against a Database in Azure by running Update-Database

This post describes how to run Entity Framework’s code-first migrations against a database located in the Windows Azure. This is done by running Update-Database commandlet with suitable switches, see below.

The problem and symptoms

Okay, so you’re developing your MVC+EF cool web app with a database in Azure, and you’re using code-first migrations. Cool! What’s nice with code-first-migrations is the fact they are run automatically even in the cloud the next time your app is running (as long as you publish your app with that little box ticked – something like in the screen capture below). But wait – what if there are conflicts – what kind of errors are you going to get?

 

Azure Web Publish

Azure Web Publish

Not very useful ones, I’m afraid, and it’s a pain navigating the Azure portal to fetch the log files. At some point – for me, it wasn’t the first time I ran the web app, but the phase when I was logging in – you’ll be getting the error the migrator internally throws. That might be enough to point you to the right direction, and maybe you’ll be able to figure out what’s wrong! But if that’s not the case, here’s the way to run Update-Database against your Azure Database!

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Solving the “Spatial types and functions are not available …” -problem

Spatial SQL types

This page describes mutiple ways on how to fix the exception ‘Spatial types and functions are not available for this provider because the assembly ‘Microsoft.SqlServer.Types’ version 10 or higher could not be found.‘ which comes up during debugging or publishing your program, app or service using DbGeography.

Symptoms

While running a console program or perhaps installing an ASP.NET MVC website on a machine, where SQL Server (apart from the one that comes with the Visual Studio) has not been installed, you may encounter the following error:

At least for me, this was baffling as that assembly was included in the project, and would compile and run flawlessly on other machines, just not on this one. I’m documenting here all the possible fixes to the issue I am aware of.

Problem / Reason

For me, the actual reason was that even though the DLL was loaded and included in the project as a nuget package, the actual native assemblies for this dll were not loaded to memory, as this needs to be done in the runtime. This issue was made worse by the fact that I first created this solution on a machine, where SQL Server was installed, so I was very much oblivious of the issue until it hit me on the face while trying to run my program on this particular machine, which did not have SQL Server.

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Fixing the error: “Column XX in table dbo.YY is of a type that is invalid for use as a key column in an index.”

entity-framework-logo

While using Entity Framework and code-first migrations, Entity Framework (EF) creates the indexes for you – but what if you need to create a custom one, explicitly based on certain field / column? Then you’ll have to tell EF which one to use as a key column. Usually, it’s easy – you just add the following annotation to the columns you’ll be using:

(example stripped of extra code and other columns for clarity)

And after adding the migration (Add-Migration… commandlet) you get something like this:

But what if, when running Update-Database, you get an error like:

There’s a quick and simple solution.

Solution

This exception comes from the fact that indexes in EF have the maximum length of 900 chars. If you are like me, you’ll have been a little lazy and you have created your string-typed model variables without specifying a maximum length for them, and this causes the length of the index values to be way too long.

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Fixing “An error occurred while updating the entries” while running code-first migrations in MVC 5 app

Update-Database error

This post describes an issue with EF’s code-first migrations, when mapping between DB’s DateTime and C#’s DateTime kind of fails, and results in Update-Database cmdlet failing. It’s more or less a prime example of a situation, where the error itself tells very little about the actual issue, and since debugging code-first migrations is kind of difficult (see the best tips for that here!), it’s cumbersome to investigate.

Symptoms

While running Update-Database in a code-first ASP.NET MVC5 + EF6 -project, you get a following (or similar) error:

An error occurred while updating the entries. See the inner exception for details.

The whole, pretty terrifying error message is the following:

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