Skip to main content

Cascade delete is not working anymore in EF with SQLite

Two in one. In today post we will talk about two different topics:

  1. An example from real life that shows why unit tests are important
  2. An odd behavior of SQLite combined with Entity Framework 
Why Unit Tests are important
This days we had to update an application with the latest and greatest version of Entity Framework and SQLite. After a few hours of working we manage to update SQLite and EF to the new version and we manage to make the application to compile and start.
Now was the moment of true, to check if the unit tests are still green. And surprise, some of them are red, even if the application seems to run without any kind of problem. It seems that in the new version of EF or SQLite the behavior or functionality of a specific feature was changed.

Odd behavior of SQLite and Entity Framework
Before the update:
PRAGMA foreign_keys = ON;
DELETE FROM CarsHistory 
    WHERE (julianday(datetime('now'))-julianday(CarBuyDate))>360
Executed as a SQL command from Entity Framework used to trigger also the delete cascade in the tables around CarsHistory. This was the expected behavior, taking into account that delete cascade feature was activated for that tables.
With the latest version of EF (6.1) in combination with SQLite NuGet Package (1.0.94) we had a big surprise. The cascade deletion was not triggered anymore by the above command. We were lucky with unit tests that cached this problem immediately after update.
The final solution was pretty “special”. Move the PRAGMA command from the command query to the connection string.
Connection string:
data source=C:\Dbs\myCardDb.db;foreign keys=true;
Command:
DELETE FROM CarsHistory 
   WHERE (julianday(datetime('now'))-julianday(CarBuyDate))>360
It seems that the old method to trigger a cascade delete is not anymore supported.


In conclusion we learn that unit tests can be useful to catch odd behavior, even the one related to frameworks updates. Also, it seems that from time to time the behavior of canonical commands can change.

Comments

  1. How we can integrate SQLite with EF into a .Net Application?

    ReplyDelete
    Replies
    1. I think that this link would be useful for you http://bricelam.net/2012/10/entity-framework-on-sqlite.html

      Delete

Post a Comment

Popular posts from this blog

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

Fundamental Books of a Software Engineer (version 2018)

More then six years ago I wrote a blog post about fundamental books that any software engineer (developer) should read. Now it is an excellent time to update this list with new entries.

There are 5 different categories of books, that represent the recommended path. For example, you start with Coding books, after that, you read books about Programming, Design and so on.
There are some books about C++ that I recommend not because you shall know C++, only because the concepts that you can learn from it.

Coding

Writing solid codeCode completeProgramming Pearls, more programming pearls(recommended)[NEW] Introduction to Algorithms

Programming

Refactoring (M. Fowler)Pragmatic ProgrammerClean code[NEW] Software Engineering: A Practitioner's Approach[NEW] The Mythical Man-Month[NEW] The Art of Computer Programming

Design

Applying UML and Patterns (GRASP patterns)C++ coding standards (Sutter, Alexandrescu)The C++ programming language (Stroustrup, Part IV)Object-oriented programming (Peter Coad)P…