The type or namespace name 'EntityFrameworkCore' does not exist in the namespace 'Microsoft

2
votes

I try to do Razor ContosoUniversity (renamed in ContsoObserve initally) for Visual Studio 2017 and get error my .csproj is 

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.0.1" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.1" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Utils" Version="2.0.1" />
  </ItemGroup>
  <ItemGroup>
    <PackageReference Update="Microsoft.NETCore.App" Version="2.0.4" />
  </ItemGroup>
  <ItemGroup>
        <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.1" />
    </ItemGroup>
</Project>

I installed all that packages in NuGet

and when I 

dotnet aspnet-codegenerator razorpage -m Student -dc SchoolContext -udl -outDir Pages\Students --referenceScriptLibraries

get

Build FAILED. Data\SchoolContext.cs(5,17): error CS0234: The type or namespace name 'EntityFrameworkCore' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\About.cshtml.cs(5,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Contact.cshtml.cs(5,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Error.cshtml.cs(6,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Index.cshtml.cs(6,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Program.cs(7,28): error CS0234: The type or namespace name 'Hosting' does not exist in the namespace 'Microsoft.AspNetCore' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Program.cs(8,28): error CS0234: The type or namespace name 'Configuration' does not exist in the namespace 'Microsoft.Extensions' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Program.cs(9,28): error CS0234: The type or namespace name 'Logging' does not exist in the namespace 'Microsoft.Extensions' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(5,28): error CS0234: The type or namespace name 'Builder' does not exist in the namespace 'Microsoft.AspNetCore' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(6,28): error CS0234: The type or namespace name 'Hosting' does not exist in the namespace 'Microsoft.AspNetCore' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(7,28): error CS0234: The type or namespace name 'Configuration' does not exist in the namespace 'Microsoft.Extensions' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(10,17): error CS0234: The type or namespace name 'EntityFrameworkCore' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\About.cshtml.cs(9,31): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Program.cs(39,23): error CS0246: The type or namespace name 'IWebHost' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(10,34): error CS0246: The type or namespace name 'DbContext' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(21,16): error CS0246: The type or namespace name 'IConfiguration' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Contact.cshtml.cs(9,33): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(33,31): error CS0246: The type or namespace name 'IApplicationBuilder' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(33,56): error CS0246: The type or namespace name 'IHostingEnvironment' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(16,16): error CS0246: The type or namespace name 'DbSet<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(16,24): error CS0246: The type or namespace name 'IConfiguration' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Error.cshtml.cs(10,31): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(17,16): error CS0246: The type or namespace name 'DbSet<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(18,16): error CS0246: The type or namespace name 'DbSet<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(20,49): error CS0246: The type or namespace name 'ModelBuilder' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(20,33): error CS0115: 'SchoolContext.OnModelCreating(ModelBuilder)': no suitable method found to override [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Index.cshtml.cs(10,31): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(12,30): error CS0246: The type or namespace name 'DbContextOptions<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] 0 Warning(s) 28 Error(s) I try unload and reload project. Same result.

I add and errors count decrease

Build FAILED.

Data\SchoolContext.cs(5,17): error CS0234: The type or namespace name 'EntityFrameworkCore' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\About.cshtml.cs(5,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Contact.cshtml.cs(5,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Error.cshtml.cs(6,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Index.cshtml.cs(6,32): error CS0234: The type or namespace name 'RazorPages' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Startup.cs(10,17): error CS0234: The type or namespace name 'EntityFrameworkCore' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\About.cshtml.cs(9,31): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(10,34): error CS0246: The type or namespace name 'DbContext' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Contact.cshtml.cs(9,33): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Error.cshtml.cs(10,31): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(16,16): error CS0246: The type or namespace name 'DbSet<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Pages\Index.cshtml.cs(10,31): error CS0246: The type or namespace name 'PageModel' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(17,16): error CS0246: The type or namespace name 'DbSet<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(18,16): error CS0246: The type or namespace name 'DbSet<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(20,49): error CS0246: The type or namespace name 'ModelBuilder' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(20,33): error CS0115: 'SchoolContext.OnModelCreating(ModelBuilder)': no suitable method found to override [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] Data\SchoolContext.cs(12,30): error CS0246: The type or namespace name 'DbContextOptions<>' could not be found (are you missing a using directive or an assembly reference?) [C:\Users\STR\source\repos\ContosoObserve\ContosoObserve\ContosoObserve.csproj] 0 Warning(s)

3
c#razorasp.net-corevisual-studio-2017
Have you done dotnet restore to get all the nuget packages? – Neil
yes. of cource. I add <PackageReference Include="Microsoft.AspNetCore" Version="2.0.1" /> and errors count turn from 28 to 17 – streamc

3 Answers

6
votes

Change your package reference to Microsoft.AspNetCore.All (currently verrsion 2.0.3). That will include Entity Framework (plus more than you will need).

Also, don't use Update on the PackageReference element, use Include.

0
votes

I was getting the same error message even though I have already installed "Microsoft.EntityFrameworkCore" on Visual Studio 2019. I did uninstall & reinstall and it worked fine.

0
votes

Assuming your IDE is Visual studio 2017 or 2019, Go to the Nuget package manager, search and install the package(s) that start with the words Microsoft.EntityFrameworkCore they are about 3 packages in number. The errors will disappear