Connectster.Shopify.ShopifyCommunicator.GetAllMetafields C# (CSharp) Method

            public List<ShopifyMetafield> GetAllMetafields(ShopifyStoreAuth storeAuth, int? limit,
                                                       DateTime? createdMin, DateTime? createdMax, DateTime? updatedMin,
                                                       DateTime? updatedMax,
                                                       string fieldNamespace, string key, string valueType,
                                                       int? productId)
            {
            //Todo: Should we make this take a "dictionary" and then simply do "foreach key in dictionary"
            if (!(valueType == "string" || valueType == "integer"))
            {
                throw new ArgumentException("valueType can only be 'string' or 'integer'");
            }
            if (limit > 250 || limit < 0)
            {
                throw new ArgumentException("limit must be between 1 and 250 inclusive");
            }
            if (storeAuth == null)
            {
                throw new ArgumentNullException("storeAuth");
            }
            if (productId == null && productId < 1)
            {
                throw new ArgumentException("productId must be >0");
            }

            List<ShopifyMetafield> returnList = limit != null
                                                    ? new List<ShopifyMetafield>((int) limit)
                                                    : new List<ShopifyMetafield>();

            var sbUrl = new StringBuilder();
            sbUrl.Append(_protocol + storeAuth.StoreSubDomain + _domain + "/admin/");

            if (productId != null)
            {
                sbUrl.Append("products/" + productId + "/");
            }
            sbUrl.Append("metafields.xml?");
            //Append each of the filter terms.
            if (limit != null)
            {
                sbUrl.Append("limit=" + limit);
            }
            if (createdMin != null)
            {
                sbUrl.Append("&created_at_min=" + HttpUtility.UrlEncode(DateTimeToShopifyString((DateTime) createdMin)));
            }
            if (createdMax != null)
            {
                sbUrl.Append("&created_at_max=" + HttpUtility.UrlEncode(DateTimeToShopifyString((DateTime) createdMax)));
            }
            if (updatedMin != null)
            {
                sbUrl.Append("&updated_at_min=" + HttpUtility.UrlEncode(DateTimeToShopifyString((DateTime) updatedMin)));
            }
            if (updatedMax != null)
            {
                sbUrl.Append("&updated_at_max=" + HttpUtility.UrlEncode(DateTimeToShopifyString((DateTime) updatedMax)));
            }
            if (!string.IsNullOrEmpty(key))
            {
                sbUrl.Append("&key=" + HttpUtility.UrlEncode(key));
            }
            if (!string.IsNullOrEmpty(fieldNamespace))
            {
                sbUrl.Append("&namespace=" + HttpUtility.UrlEncode(fieldNamespace));
            }
            if (valueType != string.Empty)
            {
                sbUrl.Append("&value_type=" + HttpUtility.UrlEncode(valueType));
            }

            XmlDocument xDoc = ShopifyGet(sbUrl.ToString().Replace("?&", "?"),
                                          HashString(_appAuth.Secret + storeAuth.StoreAuthToken));

            if (xDoc == null)
            {
                //ShopifyGet should be logging/reporting the error
                return null;
            }
            XmlNodeList metaFields = xDoc.SelectNodes("//metafields/metafield");

            if (metaFields != null)
                foreach (XmlNode metaField in metaFields)
                {
                    var metaFieldDoc = new XmlDocument();
                    metaFieldDoc.AppendChild(metaFieldDoc.ImportNode(metaField, true));
                    var serializedResponse =
                        new ShopifyResponse<ShopifyMetafield>(metaFieldDoc);

                    if (serializedResponse.State == ResponseState.OK)
                    {
                        returnList.Add(serializedResponse.ResponseObject);
                    }
                    else
                    {
                        //Log this error, ignore this metafield and continue with call so we can return the properly formatted metafields
                        XmlNodeList idNode = metaField.SelectNodes("//id");
                        if (idNode != null)
                        {
                            string metafieldId = idNode.Count > 0 ? idNode[0].InnerText : "null";
                            Logger.ErrorFormat(
                                "ShopifyCommunicator()::GetAllMetafields(): Couldn't parse metafield ({0}) returned in page of metafields.",
                                metafieldId);
                        }
                    }
                }
            return returnList;
        }