using Microsoft.EntityFrameworkCore;

namespace CosmosTestingApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
            DoWork().GetAwaiter().GetResult();

            Console.ReadKey();
        }

        private static async Task<int> DoWork()
        {
            var endpoint = "https://localhost:8081";
            var cosmosKey = "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==";
            var DbName = "TestDatabase";

            using (var ctx = new PetContext(new DbContextOptionsBuilder<PetContext>().LogTo(Console.WriteLine).UseCosmos(endpoint, cosmosKey, DbName).Options))
            {
                ctx.Cats.Add(new Cat() { Id = "Cat|1", Name = "First Cat" });
                ctx.Cats.Add(new Cat() { Id = "Cat2", Name = "Second Cat" });
                await ctx.SaveChangesAsync();
            }

            using (var ctx2 = new PetContext(new DbContextOptionsBuilder<PetContext>().LogTo(Console.WriteLine).UseCosmos(endpoint, cosmosKey, DbName).Options))
            {
                var cat2 = await ctx2.Cats.Where(c => c.Id == "Cat2").SingleAsync();
                Console.WriteLine($"Cat name: {cat2.Name}");
                var cat1 = await ctx2.Cats.Where(c => c.Id == "Cat|1").SingleAsync();
                Console.WriteLine($"Cat name: {cat1.Name}");
            }

            return 0;
        }
    }
}

using Microsoft.EntityFrameworkCore;

namespace CosmosTestingApp
{
    public class PetContext: DbContext
    {
        public PetContext(DbContextOptions<PetContext> options) : base(options)
        {
        }

        public DbSet<Cat> Cats { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.EnableSensitiveDataLogging();
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<Cat>(e =>
            {
                e.ToContainer("TestContainer");
                e.HasPartitionKey(s => s.Id);
                e.HasDiscriminator<string>("Discriminator");
            });
        }
    }
}

namespace CosmosTestingApp
{
    public class Cat
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public string Discriminator { get; set; }
    }
}

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Cosmos" Version="9.0.0" />
  </ItemGroup>

</Project>