Entity Framework core : DbContextOptionsBuilder' does not contain a definition for 'usesqlserver' and no extension method 'usesqlserver'

问题

I'm new to EF core and I'm trying to get it to work with my asp.net core project.

I get the above error in my startup.cs when trying confiugure the dbcontext to use a connection string from config. I'm following this tutorial : https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/intro

The problematic code in startup.cs :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;
using tracV2.models;
using tracV2.data;

namespace tracV2
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();

            services.AddSingleton<IConfiguration>(Configuration);

            string conn = Configuration.GetConnectionString("optimumDB");

            services.AddDbContext<tracContext>(options => options.usesqlserver(conn));
        }

The usesqlserver method is recognized if I put it directly into the context :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace tracV2.data
{
    public class tracContext : DbContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer("myrealconnectionstring");
        }

All my reasearch online points to missing references, but I can't seem to find out which one i'm missing(see image).references

Any help would be greatly appreciated,

Thanks

回答1:

This is a known issue in the project system. See dotnet/project-system#1741

回答2:

We install Microsoft.EntityFrameworkCore.SqlServer NuGet Package.

Microsoft.EntityFrameworkCore.SqlServer

PM > Install-Package Microsoft.EntityFrameworkCore.SqlServer

Then,

   services.AddDbContext<AspDbContext>(options =>
       options.UseSqlServer(config.GetConnectionString("optimumDB")));

Update do not forget to add using Microsoft.EntityFrameworkCore; namespace

回答3:

adding using Microsoft.EntityFrameworkCore;

manually solved the problem for me

Found that here

回答4:

Install below NuGet Package will solve your issue

Microsoft.EntityFrameworkCore.SqlServer

Install-Package Microsoft.EntityFrameworkCore.SqlServer

回答5:

I was using Visual Studio Code.

1) Try to install the package 'Microsoft.EntityFrameworkCore.SqlServer' by specifying the version number.

VS Code:

'dotnet add package Microsoft.EntityFrameworkCore.SqlServer -v 1.1.1'

Visual Studio:-

'Install-Package Microsoft.EntityFrameworkCore.SqlServer -v 1.1.1'

Refer the link 'Package 'Microsoft.EntityFrameworkCore.SqlServer' is incompatible with 'all' frameworks in the project' for doing it.

2) Then add the namespace 'using Microsoft.EntityFrameworkCore;' manually in the Startup.cs file.

Refer the below link https://github.com/aspnet/EntityFramework/issues/7891.

3) If you get any dependency issue for 'Microsoft.EntityFrameworkCore.SqlServer.Design', like "Package 'Microsoft.EntityFrameworkCore.Design' is incompatible with 'all' frameworks in project" ,we need to run the below command,

VS Code:-

dotnet add package Microsoft.EntityFrameworkCore.Design -v 1.1

Visual Studio

Install-Package Microsoft.EntityFrameworkCore.Design -v 1.1

回答6:

Project -> ManageNugetPackages -> Browse -> Search "Microsoft.EntityFrameworkCore.SqlServer" and install or update.

回答7:

Follow the steps below.

Install Entity Framework Core Design and SQL Server database provider for Entity Framework Core:

dotnet add package Microsoft.EntityFrameworkCore.Design
dotnet add package Microsoft.EntityFrameworkCore.SqlServer

Import Entity Framework Core:

using Microsoft.EntityFrameworkCore;

And configure your DbContext:

var connectionString = Configuration.GetConnectionString("myDb");
services.AddDbContext<MyDbContext>(options => 
    options.UseSqlServer(connectionString)
);

回答8:

I believe this can be solved by adding a project reference to Microsoft.EntityFrameworkCore.SqlServer.Design

Install-Package Microsoft.EntityFrameworkCore.SqlServer.Design

Microsoft.EntityFrameworkCore.SqlServer wasn't directly installed in my project, but the .Design package will install it anyway as a prerequisite.

回答9:

first add Install-Package Microsoft.EntityFrameworkCore.SqlServer

next add in your .cs file using Microsoft.EntityFrameworkCore;

finally add this in your core Startup.cs

  public void ConfigureServices(IServiceCollection services)
        {
            services.AddEntityFrameworkSqlServer().AddDbContext<ApplicationContext>(options => options.UseSqlServer(Configuration.GetConnectionString("MovieContext")));
        }

回答10:

As mentioned by top scoring answer by Win you may need to install Microsoft.EntityFrameworkCore.SqlServer NuGet Package, but please note that this question is using asp.net core mvc. In the latest ASP.NET Core 2.1, MS have included what is called a metapackage called Microsoft.AspNetCore.App

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/metapackage-app?view=aspnetcore-2.2

You can see the reference to it if you right-click the ASP.NET Core MVC project in the solution explorer and select Edit Project File

You should see this metapackage if ASP.NET core webapps the using statement

<PackageReference Include="Microsoft.AspNetCore.App" />

Microsoft.EntityFrameworkCore.SqlServer is included in this metapackage. So in your Startup.cs you may only need to add:

using Microsoft.EntityFrameworkCore;

回答11:

I got around this by simply:

Add SqlServerDbContextOptionsExtensions to the class in question Resolve SqlServerDbContextOptionsExtensions

This fixes the issue, must be missing some reference by default.

回答12:

For anyone still having this problem: Use NuGet to install: Microsoft.EntityFrameworkCore.Proxies

This problem is related to the use of Castle Proxy with EFCore.

回答13:

Wow so many answers yet none mentioned this Microsoft.EntityFrameworkCore.InMemory package!

Add the reference to this package: <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="2.2.2" /> and you should be good to go.

回答14:

If you are facing this issue in case of Sqlite then

. I think this is the problem with version of Sqlite,I had the same problem when I was using this versions of SqLite

Version 2.2.4:

After checking version here I changed the version then it worked.

No error after using this

Version 2.1.2:

回答15:

Copying the following code into the TodoApi.csproj from https://github.com/aspnet/Docs/tree/master/aspnetcore/tutorials/first-web-api/sample/TodoApi solved similar issue for me.

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <Folder Include="wwwroot\" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.0" />
  </ItemGroup>

  <ItemGroup>
    <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" />
  </ItemGroup>

</Project>

Microsoft.AspNetCore.All may be excessive but it includes EntityFrameworkCore

回答16:

For asp.net core version 2.1 make sure to add the following package to fix the problem. (At least this fix the issue using SQLite)

dotnet add package Microsoft.EntityFrameworkCore.Sqlite
dotnet add package Microsoft.EntityFrameworkCore.Design

Here is the reference of the documentation using SQLite with entity framework core. https://docs.microsoft.com/en-us/ef/core/get-started/netcore/new-db-sqlite

回答17:

I had to use the line

 services.AddEntityFrameworkSqlite().AddDbContext<MovieContext>(options => options.UseSqlServer(Configuration.GetConnectionString("MovieContext")));

in the ConfigureServices method in the Startup.cs

回答18:

I had this trouble when I moved to Microsoft.EntityFrameworkCore.SqlServer v3.0.0 and Microsoft.EntityFrameworkCore.Tools v3.0.0

When I changed back to v2.2.6 on both libraries, the error went away. This is more of a workaround than a solution but it'll get you up and running till the issue is fixed.

回答19:

For me this issue happened with Visual Studio Code and I was able to fix with 2 steps:

Manually adding using Microsoft.EntityFrameworkCore;
Running dotnet build in terminal.

来源：https://stackoverflow.com/questions/43098065/entity-framework-core-dbcontextoptionsbuilder-does-not-contain-a-definition-f

标签

asp.net-core

entity-framework-core