Getting Null Exception for Entity Framework core 1.1

Question

I am getting null exception for configure Service. I am using Entity Framework 1.1, previously use core 1.0 and have no issue, not sure what I am missing here

Error In Startup.cs --> at Services.AddDbContext...

 {System.ArgumentNullException: Value cannot be null.
 Parameter name: connectionString
 at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty(String value, String parameterName)
at   Microsoft.EntityFrameworkCore.SqlServerDbContextOptionsExtensions.UseSqlServer(D bContextOptionsBuilder optionsBuilder, String connectionString, Action`1 sqlServerOptionsAction)
at App.WebDashboard.Startup.<ConfigureServices>b__4_0(DbContextOptionsBuilder options)
at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.DbContextOptionsFactory[TContext](IServiceProvider applicationServiceProvider, Action`2 optionsAction)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)
at  Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass16_0.<RealizeService>b__0(ServiceProvider provider)
at Microsoft.Extensions.Internal.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
at lambda_method(Closure , IServiceProvider , Object[] )
at Microsoft.AspNetCore.Mvc.Internal.TypeActivatorCache.CreateInstance[TInstance](IServiceProvider serviceProvider, Type implementationType)
at Microsoft.AspNetCore.Mvc.Controllers.DefaultControllerFactory.CreateController(ControllerContext context)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker. <InvokeNextResourceFilter>d__22.MoveNext()}

Startup.cs

 public void ConfigureServices(IServiceCollection services)
    {
        // Add framework services.
        services.AddApplicationInsightsTelemetry(Configuration);

        services.AddDbContext<TestDbContext>(options =>
           options.UseSqlServer(Configuration.GetConnectionString("UCASAppDatabase")));

        services.AddMvc();
    }

Connection string in appsetting.json

"ConnectionStrings": {
  "UCASAppDatabase": "Data Source=mydatasource;Initial Catalog=UCAS-DB;Integrated Security=True"
}

DbContext

 public class TestDbContext : DbContext
 {
    public TestDbContext(DbContextOptions<TestDbContext> options) : base(options)
    { }

    public DbSet<TestModel> TestModels { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<TestModel>().ToTable("TestTable");
    }
}

Entity Class

[Table("TestTable")]
public class TestModel
{
    [Key]
    public int ID { get; set; }
    public string Name { get; set; }
}

Controller class where I am trying to read data

public class HomeController : Controller
{
    private readonly TestDbContext _context;
    public HomeController(TestDbContext context)
    {
        this._context = context;
    }

    public IActionResult About()
    {
        var query = (from b in _context.TestModels
                     select b).ToList();

        ViewData["Message"] = "Your application description page.";

        return View();
    }

Appsettings.json

 public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();

Can you test what is Configuration.GetConnectionString("UCASAppDatabase") returning? — Ricardo Peres
– Ricardo Peres, Commented Nov 22, 2016 at 14:44
Put all appsetting.json and try get your connection string using Configuration["Data:ConnectionStrings:UCASAppDatabase"]) — M. Wiśnicki
– M. Wiśnicki, Commented Nov 22, 2016 at 14:45
mmm, I am getting null value for Configuration["Data:ConnectionStrings:UCASAppDatabase"]) — K.Z
– K.Z, Commented Nov 22, 2016 at 14:47
Possible duplicate of What is a NullReferenceException, and how do I fix it? — mybirthname
– mybirthname, Commented Nov 22, 2016 at 14:48

K.Z · Accepted Answer · 2016-11-23 07:58:19Z

8

found the answer, need to sorted connection-String in appsettings.json

"Data": {
  "UCASAppDatabase": {
    "ConnectionString": "Data Source=mysource;Initial Catalog=UCAS-DB;Integrated Security=True;Persist Security Info=True"
  }
}

and in Startup.cs

public void ConfigureServices(IServiceCollection services)
    {
        services.AddApplicationInsightsTelemetry(Configuration);

        services.AddDbContext<TestDbContext>(options =>
           options.UseSqlServer(Configuration["Data:UCASAppDatabase:ConnectionString"]));

        services.AddMvc();
    }

answered Nov 23, 2016 at 7:58

K.Z

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1 Comment

Richard Bailey Over a year ago

answer related to: jakeydocs.readthedocs.io/en/latest/data/entity-framework-6.html

Ricardo Peres · Accepted Answer · 2016-11-22 14:54:02Z

1

By convention, the file should be called appsettings.json, not appsetting.json. Can you make sure your Startup file is referencing it right?

answered Nov 22, 2016 at 14:54

Ricardo Peres

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1 Comment

K.Z Over a year ago

it is appsettings.json, miss type in writing my question, also update my question at bottom

Chamila Maddumage · Accepted Answer · 2019-01-02 11:46:25Z

0

I had the same problem. In my property class I just added the key DataAnnotations for the primary key attribute as follows and error was solved.

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Text;

namespace Treat_Data.Model
{
    public class Restaurant
    {
        [Key]
        public int Restaurant_ID { get; set; }//this is the primary key
        public string Name { get; set; }
        public string Address { get; set; }
        public string Open_Hours { get; set; }

    }
}

answered Jan 2, 2019 at 11:46

Chamila Maddumage

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Getting Null Exception for Entity Framework core 1.1

Error In Startup.cs --> at Services.AddDbContext...

Startup.cs

Connection string in appsetting.json

DbContext

Entity Class

Controller class where I am trying to read data

Appsettings.json

3 Answers 3

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Error In Startup.cs --> at Services.AddDbContext...

Startup.cs

Connection string in appsetting.json

DbContext

Entity Class

Controller class where I am trying to read data

Appsettings.json

3 Answers 3

1 Comment

1 Comment

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