DocumentDb repo for Azure DocumentDb

DocumentDbStore.cs

public class DocumentDbStore : IStorage
    {
        private string endpoint = "rootUri";
        private string authKey = "key";
        
        private readonly DocumentClient _client;
        private readonly DocumentCollection _col;

        public DocumentDbStore()
        {
            _client = new DocumentClient(new Uri(endpoint), authKey);

            var databases = _client.CreateDatabaseQuery().Where(x => x.Id == "DbName").ToList();
            var database = databases.Any() ? databases.First() : _client.CreateDatabaseAsync(new Database {Id = "DbName"}).Result;

            var collections = _client.CreateDocumentCollectionQuery(database.SelfLink)
                     .Where(x =>  x.Id == "CollectionName").ToArray();

            _col = collections.Any()
                ? collections.First()
                : _client.CreateDocumentCollectionAsync(database.SelfLink,
                    new DocumentCollection {Id = "CollectionName"}).Result;
        }

        public void Store<TObjectType>(TObjectType obj) where TObjectType : class, IPersistable
        {
            var existing =
                _client.CreateDocumentQuery(_wishlists.SelfLink,
                    "SELECT * FROM CollectionName c WHERE c.Id = '" + obj.Id + "'").ToList();

            if (existing.Any()) // This is REALLY POOR - but I'm not sure how to replace a TObjectType yet..
            {
                var first = existing.First();
                var selfLinkForUpdate = (string) first._self.ToString();
                var deleteResult = _client.DeleteDocumentAsync(selfLinkForUpdate).Result;
            }
            
            var resp = _client.CreateDocumentAsync(_wishlists.SelfLink, obj).Result;
        }

        public TObjectType Get<TObjectType>(string id) where TObjectType : class, IPersistable
        {
            var list = _client.CreateDocumentQuery<TObjectType>(_col.SelfLink)
                .Where(d => d.WishlistId == id).ToList();

            return list.FirstOrDefault() as TObjectType;
        }
    }