Transaction Per Request Middleware Not working

Question

I am trying to add a middleware so that transaction begins at the beginning of the request and commits or rollbacks depending on the situation. This is my middleware:

    public class TransactionPerRequestMiddleware
    {
      private readonly RequestDelegate next_;

      public TransactionPerRequestMiddleware(RequestDelegate next)
      {
        next_ = next;
      }

      public async Task Invoke(HttpContext context, AppDbContext dbContext)
       {
        var is_everything_ok = true;
        var transaction = dbContext.Database.BeginTransaction(
            System.Data.IsolationLevel.ReadCommitted);
        if (context.Response.StatusCode != 200 && is_everything_ok)
        {
            is_everything_ok = false;
        }

        await next_.Invoke(context);

        if ((context.Response.StatusCode == 200 || 
         context.Response.StatusCode == 302) && is_everything_ok)
        {
            transaction.Commit();
        }
        else
        {
            transaction.Rollback();
        }
      }
    }

I registered the above middleware in Startup.cs

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
      app.UseMiddleware<TransactionPerRequestMiddleware>();
    }

I have a method in service which performs two database operations one after another.

    public void method()
    {
      databaseOperation1();
      databaseOperation2();
    }

If exception occurs in databaseOperation2() , databaseOperation1() is not rolling back currently. I am trying to implement Unit Of Work for each web request.

Thanks in advance.