EF core: entity cannot be tracked

We use EF core to store a bulk of data with an auto-number primary key. The auto-number is an Identity column in Sql Server. When inserting a large amount of records with related children we encounter this error:

System.InvalidOperationException entity cannot be tracked because another instance with the same key value is already being tracked

The github bug that described the same bug: Adding multiple new entities at the same time results in System.InvalidOperationException entity cannot be tracked because another instance with the same key value is already being tracked #13937 The same message, but explicit no use of identity. This got us thinking.

Digging a little deeper we discovered that the TemporaryIntValueGenerator used in EF core used int.minvalue + 1000. That is the first temporary Id used in EF core to track newly created records with an Identity column. Our exception occurs with a large amount of record, maybe 1000? Would the identity value generated in Sql already be used as a temporary value? The identity columns we use start at -2147483648 (int.minvalue) and increase by 1.

We implemented our own TemporaryNumberValueGenerator that start with 214748364 (int.maxvalue / 10) and use that in the OnModelCreating override:

protected override void OnModelCreating(ModelBuilder m) {
   base.OnModelCreating(m);
   m.Entity<MY_TYPE>()
    .Property(x => x.Id)
    .HasValueGenerator<TemporaryIntValueGeneratorMaxValue>();
}
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Computer setup COVID-19 update

I invested in a good computer setup for working-from-home a while ago. When the lockdown for COVID-19 came I was prepared. Still I made some changes and investments to go from one-day-a-week to fulltime working-from-home. Time for an update.


No cable management and I love it

The laptop

I’ve raised my laptop so I can see the slack updates next to my actual work. The clear pastic stand was from when I used only my laptop. After buying my 24 inch monitor it was stuffed away somewhere. Luckily I could still find it and raise my laptop to eye level.

Now that my laptop is always open (used it clamshell mode before) the webcam bothered me. I bought some webcam covers and installed them on all my laptops. Just for some ease of mind.

With everybody working/learning from home my wifi wasn’t stable enough for remote desktop. I bought the thunderbolt UTP adapter and use a wired connection now. Network connection and speed are stable now.

Extra

Slack, Skype and Zoom are the places we meet-up. For some privacy and better call quality I use the AirPods 2. Connecting to Apple devices is as easy as clicking a button. The wireless charging case is a nice feature too.

My logitech K800 keyboard and Performance MX mouse use the unifying receiver. Seemed to be vulnerable for hacking. Logitech released an update and installation was easy. https://support.logi.com/hc/articles/360035037273 (Firmware Update Tool)

Sometimes writing with pen on paper is needed. I have a stack of post-it notes next to my case with pens.

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Logging from Automapper

We’ve been using automapper to convert objects for some time. Now I have the need for logging to help bugtracking. Below a short list of sources how we set this up.

// ConfigureServices(IServiceCollection services) stuff

services.AddSingleton<MapperConfiguration, 
                      AutomapperConfiguration>();
services.AddTransient(serviceprovider => {
   var cfg = serviceprovider.GetService<MapperConfiguration>();
   // inject the serviceprovider so everything is available
   // and the ILogger is too
   return cfg.CreateMapper(serviceprovider.GetService);
});
// AutomapperConfiguration stuff

// old automapper
/* Func<ResolutionContext, ILogger> createLogger = (c) =>
   c.Mapper.ServiceCtor.Invoke(typeof(ILogger)) as ILogger; */

// new automapper 
Func<ResolutionContext, ILogger> createLogger = (c) =>
   c.Options.ServiceCtor.Invoke(typeof(ILogger)) as ILogger;

config.CreateMap<ObjectA, ObjectB>()
      .ConvertUsing((s, d, c) => {
         // important stuff removed ....
         var logger = createLogger(c);
         logger.LogWarning("Something happend");
      };

And now you’ll need a serviceprovider when unittesting. Thank you AutoMoqCore.

var automoqer = new AutoMoqer();
var configuration = automoqer.Create<AutomapperConfiguration>();
var mapper = configuration.CreateMapper(automoqer.Create);
// now test the mapping configuration with the mapper instance

We managed to find the bugs and fixed them. We’ll be using this logging solution with automapper from now on.

[edited 11 nov 2020] new automapper has the ServiceCtor in the context Options no longer in the context Mapper, code sample edited

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AutoMoqCore – auto mocking IoC

Photo by Phillip Glickman on Unsplash
Photo by Phillip Glickman on Unsplash

https://www.nuget.org/packages/AutoMoqCore/

Dependency Inversion is one of the SOLID principles. This can be applied to unittesting as well. With AutoMoqCore I can develop robust unittests that will always compile.

Focus on the smallest possible code for your unittest and let AutoMoqCore figure out the needed dependencies. Injection of mocks is automatically and can be tailored to your needs.

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Update SEQ with Powershell DSC

We user Powershell Desired State Configuration (DSC) to install everything. A new installation could be done to a clean machine or by removing existing software prior to installing it. Below is part of the script we use.

configuration DscWebServer {    
   
 Import-DscResource -ModuleName PSDesiredStateConfiguration  
    
 Node $AllNodes.NodeName {

  Script seq {
   GetScript  = { return @{} }
   TestScript = {
    # test for existing service seq
    $service = Get-Service -Name seq -ErrorAction SilentlyContinue
    if($service) { return $true }
    else { return $false }
   }
   SetScript  = {   
    $arguments = '/i ' + $using:Node.DeployLocation + '\Seq-4.2.1113.msi /qn /norestart /log ' + $using:Node.DeployLocation + '\seq.install.log'
    # msi install with logging to seq.install.log file
    Start-Process msiexec -ArgumentList $arguments -Wait
    # post install configuration to run as a windows service ...
   }
  }

 }
}

Now we want to upgrade an existing installation to preserve the data it contains.
Note: this means the installation files must support updating of existing versions. The application SEQ in this example handles updates by replacing the application and converting the data.

With the script below we can upgrade Seq version 4 to version 5.
For this we edited the installation (Script seq) to use the new msi; if the software doesn’t exist then install the newest version right away.
We also added an UpgradeSeq that depends on seq being present; there we check the version and upgrade if needed.

configuration DscWebServer {    
   
 Import-DscResource -ModuleName PSDesiredStateConfiguration  
    
 Node $AllNodes.NodeName {

  Script seq {
   GetScript  = { return @{} }
   TestScript = {
    # test for existing service seq
    $service = Get-Service -Name seq -ErrorAction SilentlyContinue
    if($service) { return $true }
    else { return $false }
   }
   SetScript  = {   
    $arguments = '/i ' + $using:Node.DeployLocation + '\Seq-5.1.3364.msi /qn /norestart /log ' + $using:Node.DeployLocation + '\seq.install.log'
    # msi install with logging to seq.install.log file
    Start-Process msiexec -ArgumentList $arguments -Wait
    # post install configuration to run as a windows service ...
   }
  }

  Script UpgradeSeq {
   DependsOn  = "[Script]seq"
   GetScript  = { return @{} }
   TestScript = {
    push-location 'c:\program files\seq'
    $version = seq.exe version
    if($version -eq '5.1.3364') { return $true }
    else { return $false }
   }
   SetScript  = {   
    # inplace upgrade
    $arguments = '/i ' + $using:Node.DeployLocation + '\Seq-5.1.3364.msi /qn /norestart /log ' + $using:Node.DeployLocation + '\seq.install.log'
    # msi install with logging to seq.install.log file
    Start-Process msiexec -ArgumentList $arguments -Wait
    # restart service to complete upgrade
    Get-Service -Name seq | Restart-Service
   }
  }

 }
}

The next version of Seq will be simple, just edit the versions in the msi and upgradeseq test in the script above. (find-and-replace 5.1.3364)

We are confident this way of working can be applied to all our upgrades, like the dotnetcore framework.

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