FunctionEf.cs

public class Function
{
    // Repository
    public IProductRepository ProductRepository { get; }

    public Function()
    {
        // Get dependency resolver
        var resolver = new DependencyResolver(ConfigureServices);

        // Get products repo
        ProductRepository = resolver.ServiceProvider.GetService<IProductRepository>();
    }

    // Use this ctor from unit tests that can mock IProductRepository
    public Function(IProductRepository productRepository)
    {
        ProductRepository = productRepository;
    }

    /// <summary>
    /// A simple function that takes an id and returns a product.
    /// </summary>
    /// <param name="input"></param>
    /// <param name="context"></param>
    /// <returns></returns>
    public async Task<Product> FunctionHandler(string input, ILambdaContext context)
    {
        int.TryParse(input, out var id);
        if (id == 0) return null;
        return await ProductRepository.GetProduct(id);
    }

    // Register services with DI system
    private void ConfigureServices(IServiceCollection services)
    {
        services.AddTransient<IProductRepository, ProductRepository>();
    }
}