Value cannot be null. (Parameter 'connectionString')

Question

Value cannot be null. (Parameter 'connectionString')

Atilla Rüstəmli 60

Hi,I was workin on my .net core MVC project and when I wanted to add another migration I go folllowing error

System.ArgumentNullException: Value cannot be null. (Parameter 'connectionString')
   at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty(String value, String parameterName)
   at Microsoft.EntityFrameworkCore.SqlServerDbContextOptionsExtensions.UseSqlServer(DbContextOptionsBuilder optionsBuilder, String connectionString, Action`1 sqlServerOptionsAction)
   at CodeAcademy_Final_Project.RegisterServices.<>c__DisplayClass0_0.<Register>b__1(DbContextOptionsBuilder opt) in C:\Users\MSI\OneDrive\Desktop\Final\CodeAcademy-Final-Project\CodeAcademy-Final-Project\RegisterServices.cs:line 25
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__DisplayClass1_0`2.<AddDbContext>b__0(IServiceProvider p, DbContextOptionsBuilder b)
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.CreateDbContextOptions[TContext](IServiceProvider applicationServiceProvider, Action`2 optionsAction)
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__DisplayClass17_0`1.<AddCoreServices>b__0(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass2_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__17`1.<AddCoreServices>b__17_1(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitIEnumerable(IEnumerableCallSite enumerableCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass2_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetServices[T](IServiceProvider provider)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.FindContextTypes()
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.FindContextType(String name)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Value cannot be null. (Parameter 'connectionString')

Anonymous

2024-02-05T06:30:02.9366667+00:00

Hi @Atilla Rüstəmlie, have you split the code and check var con= config.GetConnectionString("DefaultConnectionString") if it contains the value or not? Which environment do you use? e.g. If you are in development environment, be sure your appSettings.development.json contains such json string for connection string.
Atilla Rüstəmli 60 Reputation points

2024-02-08T18:20:16.7566667+00:00

The problem was about

var rootPath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);> Directory.SetCurrentDirectory(rootPath);

these lines of code.But now I have to remove this code when I want to do something in package manager console.

1 answer

Your answer

Anonymous

2024-02-05T06:30:02.9366667+00:00

Hi @Atilla Rüstəmlie, have you split the code and check var con= config.GetConnectionString("DefaultConnectionString") if it contains the value or not? Which environment do you use? e.g. If you are in development environment, be sure your appSettings.development.json contains such json string for connection string.
Atilla Rüstəmli 60 Reputation points

2024-02-08T18:20:16.7566667+00:00

The problem was about

var rootPath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);> Directory.SetCurrentDirectory(rootPath);

these lines of code.But now I have to remove this code when I want to do something in package manager console.

Answer 1

AgaveJoe 30,491

The error message states that the connection string was not found. In ASP.NET Core, the connection string is in configuration like the appsetting.json.

{
  "ConnectionStrings": {
    "DefaultConnectionString": "Data Source=ApplicationDbContext.db"
  },

The program.cs file reads the configuration to set the connection string.

builder.Services.AddDbContext<ApplicationDbContext>(options =>
       options.UseSqlite(builder.Configuration.GetConnectionString("DefaultConnectionString")));

We cannot see your code so it is not clear how your project is designed.

Atilla Rüstəmli 60 Reputation points

2024-02-03T09:48:47.72+00:00

Hi,thanks for an answer but I have all this but still don't work.The only difference is in my code it it like opt.UseSqlServer(config.GetConnectionString("DefaultConnection")); this .But in every other project that I wrote there was no problem.
AgaveJoe 30,491 Reputation points

2024-02-03T12:06:01.52+00:00

Again, the error message is very clear and we can only comment on the code that you share. Most likely an issue with how "config" is setup. Try running your code through the Visual Studio debugger to figure out what's wrong. If you want community debugging support then share all the relevant code so we are not forced to guess.
Atilla Rüstəmli 60 Reputation points

2024-02-03T16:49:51.0533333+00:00

But I don't get any error when I run the code.It only appears when I want to add migration.I did anything that I can do an everything that I found in internet.I also checked is opt.UseSqlServer(config.GetConnectionString("DefaultConnection")); is really gives me correct data.But the error wasn't gone
AgaveJoe 30,491 Reputation points

2024-02-03T17:54:34.5466667+00:00

The server project should be set as the startup project and contain the configuration.
You have to understand that we cannot see your source code and we have no idea how you are invoking the migration. If you are using the Packet Manager Console, then make sure the server project is the Default project (dropdown).
Atilla Rüstəmli 60 Reputation points

2024-02-08T17:21:14.6766667+00:00

I finally got what is the problem.I was using> var rootPath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);

Directory.SetCurrentDirectory(rootPath);

these lines of code in my program.cs.These lines were before "var builder=...".When I deleted these lines my migrations added .So I have to delete these lines of code when I am doing something in package manager console.Now I have problem like this.Do you know the reason why when I'm using

var rootPath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);> Directory.SetCurrentDirectory(rootPath);

these lines before builder I'm getting problem with migrations?
AgaveJoe 30,491 Reputation points

2024-02-08T17:28:10.4833333+00:00

We still cannot see your code and it is not clear why you are not following the official documentation.
Atilla Rüstəmli 60 Reputation points

2024-02-08T18:17:29.7566667+00:00

I don't know the offical documentation,which you talking about.Normally I am not even need the rootPath code in my project.But this time i got error that I never got so I writed this.But I'll find the reason.Thank for your help)

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Value cannot be null. (Parameter 'connectionString')

1 answer

Your answer