How import WebApplicationBuilder in a Class Library?

user_14960898 0
Viewed 961

I want to create an extension method for WebApplicationBuilder:

public static void AddData(this WebApplicationBuilder builder)
{
    var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
    builder.Services.AddDbContext<ApplicationDbContext>(option =>
    {
        option.UseSqlite(connectionString);
    });
}

this method works in a project that use: <Project Sdk="Microsoft.NET.Sdk.Web">, but if I put this method in a class libary then it doesn't work (<Project Sdk="Microsoft.NET.Sdk>) because it doesn't find Microsoft.AspNetCore.Builder

Otherwise, if I use <Project Sdk="Microsoft.NET.Sdk.Web"> the compiler say that there is no Main in the project.

How can I do?

Why can't I write this?

using Microsoft.AspNetCore.Builder;
asp.net .net c#
2 Answers

I had exactly the same problem but this Microsoft doc explains what you need to do.

Add

  <ItemGroup>
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
  </ItemGroup>

to your .csproj and you can then use

using Microsoft.AspNetCore.Builder;

in your regular class library which targets Microsoft.NET.Sdk.

user_5251380

I did this recently when I converted to a .Net 6 project. I wasn't able to extend the Builder either, so I added the extension to the IServiceCollection and passed in the configuration. So to use your example, my code looked more like:

public static void AddData(this IServiceCollection services, ApplicationSettings appSettings)
{
    services.AddDbContext<ApplicationDbContext>(option =>
    {
        option.UseSqlite(appSettings.ConnectionString);
    });
}

Where ApplicationSettings is a custom class that is bound to the app settings in the json. So my Program.cs has these lines:

var builder = WebApplication.CreateBuilder(args);
ConfigurationManager configuration = builder.Configuration;

var appSettings = new ApplicationSettings();
configuration.Bind(appSettings);
builder.Services.AddData(appSettings);

Using the IServiceCollection in the extension method only requires:

using Microsoft.Extensions.DependencyInjection;
user_1598280
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