Add prepareXMLRootList function

lib/msRest.ts

@@ -23,7 +23,7 @@ import {
   stripRequest, stripResponse, delay,
   executePromisesSequentially, generateUuid, encodeUri, ServiceCallback,
   promiseToCallback, promiseToServiceCallback, isValidUuid, dispatchRequest,
-  applyMixins, isNode, stringifyXML
+  applyMixins, isNode, stringifyXML, prepareXMLRootList
 } from "./util/utils";
 
 // Credentials
@@ -40,5 +40,5 @@ export {
   BasicAuthenticationCredentials, ApiKeyCredentials, ApiKeyCredentialOptions, ServiceClientCredentials, BaseFilter, LogFilter, ServiceClientOptions, ExponentialRetryPolicyFilter,
   SystemErrorRetryPolicyFilter, SigningFilter, MsRestUserAgentFilter, stripRequest, stripResponse, delay, executePromisesSequentially,
   generateUuid, isValidUuid, encodeUri, RestError, RequestOptionsBase, RequestFunction, ServiceCallback, promiseToCallback,
-  promiseToServiceCallback, isStream, dispatchRequest, RedirectFilter, applyMixins, isNode, stringifyXML
+  promiseToServiceCallback, isStream, dispatchRequest, RedirectFilter, applyMixins, isNode, stringifyXML, prepareXMLRootList
 };

lib/util/utils.ts

@@ -8,7 +8,7 @@ import { Constants } from "./constants";
 import { RestError } from "../restError";
 import { HttpOperationResponse } from "../httpOperationResponse";
 import * as xml2js from "xml2js";
-import { promisify } from "util";
+import { promisify, isArray } from "util";
 
 /**
  * Provides the fetch() method based on the environment.
@@ -279,6 +279,13 @@ export function stringifyXML(obj: any, opts?: { rootName?: string }) {
   return builder.buildObject(obj);
 }
 
+export function prepareXMLRootList(obj: any, elementName: string) {
+  if (!isArray(obj)) {
+    obj = [obj];
+  }
+  return { [elementName]: obj };
+}
+
 /**
  * Sends the request and returns the received response.
  * @param {WebResource} options - The request to be sent.