Why can't I call the UseInMemoryDatabase method on DbContextOptionsBuilder?

Question

First off, I can't use SQL Lite. Secondly the code below is giving me:

Error CS1061 'DbContextOptionsBuilder' does not contain a definition for 'UseInMemoryDatabase' and no extension method 'UseInMemoryDatabase' accepting a first argument of type 'DbContextOptionsBuilder' could be found (are you missing a using directive or an assembly reference?)

The code:

 var options = new DbContextOptionsBuilder<ProductContext>()
                     .UseInMemoryDatabase(Guid.NewGuid().ToString())
                     .Options;
 var context = new ProductContext(options);

Context

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

namespace Memory.Data
{
    public class ProductContext : DbContext
    {
        public ProductContext(DbContextOptions<ProductContext> options) : base(options)
        {

        }
        public DbSet<Category> Categories { get; set; }
        public DbSet<Product> Products { get; set; }
    }
}

My project CSPROJ file

<ItemGroup>
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.0.0" />
    <PackageReference Include="Microsoft.AspNetCore" Version="1.1.5" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="1.1.6" />
    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="1.1.3" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="1.1.5" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="1.1.0" />
    <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="1.1.2" />
    <PackageReference Include="Microsoft.VisualStudio.Web.BrowserLink" Version="1.1.3" />
  </ItemGroup>

  <ItemGroup>
    <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="1.0.3" />
  </ItemGroup>

The exact problem is that the method is just not available. I don't seem to understand why. I require enlightenment on this issue.

Answer 1

According to EF Core: Testing with InMemory reference, you need to add the Microsoft.EntityFrameworkCore.InMemory package to use UseInMemoryDatabase() extension method with DbContextOptionsBuilder:

Install-Package Microsoft.EntityFrameworkCore.InMemory

Afterwards, you can follow example given in "Writing tests" section like this:

var options = new DbContextOptionsBuilder<ProductContext>().UseInMemoryDatabase(databaseName: "database_name").Options;

using (var context = new ProductContext(options))
{
    // add service here
}

Answer 2

You need it to use UseInMemoryDatabase

<ItemGroup>
<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="3.0.0" />
</ItemGroup>

Answer 3

Visual Studio 2019: Via the console...

Tools(menu) -> NuGet Package Manager -> Package Manager Console then type dotnet add package Microsoft.EntityFrameworkCore.InMemory

Or by using the Package Manager...

Tools(menu) -> NuGet Package Manager -> Manage NuGet Packages for solution -> NuGet (tab that opened up) -> search for "inmemory" -> Select Microsoft.EntityFrameworkCore.InMemory -> Check the box Project -> Install(button)

Visual Studio CODE: Via the Terminal...

On the bottom of the screen, select Terminal(tab) then type dotnet add package Microsoft.EntityFrameworkCore.InMemory

Answer 4

Check in your NuGet Package Manager => Manage Packages for Solution, check all this packages, whether got installed in your solution or not, as below:

1. EntityFrameworkCore
2. Microsoft.EntityFrameworkCore
3. Microsoft.EntityFrameworkCore.InMemory
4. Microsoft.EntityFrameworkCore.Relational
5. Microsoft.EntityFrameworkCore.Sqlite.Core
6. Microsoft.EntityFrameworkCore.SqlServer
7. Microsoft.EntityFrameworkCore.Tools

I solved the same issues after check all the above packages been installed.

Answer 5

In Mac, open terminal in project directory or In Visual Studio Right click on project -> Tools -> Open in Terminal.

In the terminal install package by following command->

dotnet add package Microsoft.EntityFrameworkCore.InMemory