Azure Elastic Scale Client w/ Entity Framework Core (EFCore) 2.1

MultiTenantConfigurator.cs

using System;
using System.Configuration;
using System.Data.SqlClient;
using System.Linq;
using Microsoft.Azure.SqlDatabase.ElasticScale.ShardManagement;
using Microsoft.EntityFrameworkCore;

namespace eftest
{
    // todo - convert public accessors to appropriate access level
    public static class MultiTenantConfigurator
    {
        public static MyContext GetContext(int shardKey) =>
            new MyContext(
                GetDbContextOptions<MyContext>(shardKey, "shardMapManager", "My_ShardMap", "MyDbConnStringName"));

        public static DbContextOptions<TContext> GetDbContextOptions<TContext>(int shardKey,
            string shardMapConnstringName, string shardMapName, string dbConnString, int commandTimeout = 600)
            where TContext : DbContext => 
            GetDbContextOptions<int, TContext>(shardKey, shardMapConnstringName, shardMapName, dbConnString, commandTimeout);

        public static DbContextOptions<TContext> GetDbContextOptions<Tkey, TContext>(Tkey shardKey, 
            string shardMapConnstringName, string shardMapName, string dbConnString, int commandTimeout = 600) 
            where TContext : DbContext
        {
            var builder = new DbContextOptionsBuilder<TContext>();
            var conn = OpenDDRConnection(GetShardMapManager(GetConnectionString(shardMapConnstringName), shardMapName),
                shardKey, GetConnectionString(dbConnString));
            var options = builder.UseSqlServer(conn, b => b.CommandTimeout(commandTimeout));
            return options.Options;
        }

        public static string GetConnectionString(string name) => ConfigurationManager.ConnectionStrings[name].ConnectionString;

        public static ShardMap GetShardMapManager(string connString, string shardMapName)
        {
            var smm = ShardMapManagerFactory.GetSqlShardMapManager(connString, ShardMapManagerLoadPolicy.Lazy);
            var sm = smm.GetListShardMap<int>(shardMapName);
            return sm;
        }

        /// <summary>
        /// Wrapper function for ShardMap.OpenConnectionForKey() that automatically sets CONTEXT_INFO to the correct
        /// tenantId before returning a connection. As a best practice, you should only open connections using this 
        /// method to ensure that CONTEXT_INFO is always set before executing a query.
        /// </summary>
        public static SqlConnection OpenDDRConnection<T>(ShardMap shardMap, T shardingKey, string connString)
        {
            // No initialization
            //Database.SetInitializer<MyContext>(null);

            // Ask shard map to broker a validated connection for the given key
            SqlConnection conn = null;
            try
            {
                connString = MassageConnString(connString);
                conn = shardMap.OpenConnectionForKey(shardingKey, connString, ConnectionOptions.Validate);

                // Set TenantId in SESSION_CONTEXT to shardingKey to enable Row-Level Security filtering
                var cmd = conn.CreateCommand();

                cmd.CommandText = @"exec sp_set_session_context @key=N'TenantId', @value=@shardingKey";
                cmd.Parameters.AddWithValue("@shardingKey", shardingKey);
                cmd.ExecuteNonQuery();

                return conn;
            }
            catch (Exception)
            {
                conn?.Dispose();
                throw;
            }


            string MassageConnString(string connstring)  // local function
            {
                var list = connstring.Split(';').ToList();
                list.Remove(list.First(x => x.StartsWith("Data Source")));
                list.Remove(list.First(x => x.StartsWith("Initial Catalog")));
                return string.Join(";", list);
            }
        }
    }
}