Why is there no SingleOrDefaultAsync for IQueryables?
Try:
Add the following statement into the module you are working on:
// using Microsoft.EntityFrameworkCore;
Then using .NET CLI,
dotnet add package Microsoft.EntityFrameworkCore.Tools --version <version-you-want> // if ommited the latest will be installed
dotnet restore
dotnet build
using PM:
dotnet add package Microsoft.EntityFrameworkCore.Tools --version <version-you-want> // if omitted the latest will be installed
dotnet restore
dotnet build
or Package Reference:
Add on your project .csproj file
<ItemGroup>
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="<verion>" />
</ItemGroup>
// in the CLI
dotnet restore
Make sure you have added System.Data.Entity
namespace to your usings. This is an extension method, and it will not be available until you add appropriate namespace.
I fixed it by adding using Microsoft.EntityFrameworkCore;