Pass the body of POST/PUT/PATCH calls correctly.

        Following are the scenarios that have been tested to verify this:
                1. Tried sending the string
                2. Tried sending the JSON
                3. Tried sending the blob/file from browser
                4. Tried sending the binary data as ArrayBuffer from browser
                5. Tried sending the binary data as TypedArrays from browser
                6. Tried sending the binary data as node.js buffer object using node platform

Author: U-FAREAST\ramgupt

src/GraphHelper.ts

@@ -0,0 +1,48 @@
+export class GraphHelper {
+
+    /*
+        This conversion is required due to the following reasons:
+            1. Body parameter of Request method of isomorphic-fetch only accepts Blob, ArrayBuffer, FormData, TypedArrays, string.
+            2. Node.js platform does not suppport Blob, FormData. Javascript File object inherits from Blob so it is also
+                not supported in node. Therefore content of type Blob, File, FormData will only come from browsers.
+            3. Parallel to Javascript's arrayBuffer, node provides Buffer interface. Node's Buffer is able to send the arbitary 
+                binary data to the server successfully for both Browser and Node platform. Whereas sending binary data via 
+                ArrayBuffer or TypedArrays was only possible using Browser. To support both Node and Browser, `serializeContent`
+                converts TypedArrays or ArrayBuffer to `Node Buffer`.
+            4. If the data received is in JSON format, `serializeContent` converts the JSON to string.
+    */
+    public static serializeContent(content: any): any {
+        let className: string = content.constructor.name;
+
+        if (className === 'Buffer'
+            || className === 'Blob'
+            || className === 'File'
+            || className === 'FormData'
+            || typeof content === 'string') {
+            return content;
+        }
+
+        if (className === 'ArrayBuffer') {
+            content = Buffer.from(content);
+        } else if (className === 'Int8Array'
+            || className === 'Int16Array'
+            || className === 'Int32Array'
+            || className === 'Uint8Array'
+            || className === 'Uint16Array'
+            || className === 'Uint32Array'
+            || className === 'Uint8ClampedArray'
+            || className === 'Float32Array'
+            || className === 'Float64Array'
+            || className === 'DataView') {
+            content = Buffer.from(content.buffer);
+        } else {
+            try {
+                content = JSON.stringify(content);
+            } catch (error) {
+                console.log(error);
+                throw new Error('Invalid JSON content');
+            }
+        }
+        return content;
+    }
+}

src/GraphRequest.ts

@@ -4,6 +4,7 @@ import 'isomorphic-fetch';
 import { Options, URLComponents, GraphError, oDataQueryNames, GraphRequestCallback, PACKAGE_VERSION } from "./common"
 import { ResponseHandler } from "./ResponseHandler"
 import { RequestMethod } from './RequestMethod';
+import { GraphHelper } from './GraphHelper';
 
 export class GraphRequest {
     config: Options;
@@ -211,7 +212,7 @@ export class GraphRequest {
                 url,
                 { 
                     method: RequestMethod.PATCH,
-                    body: content,
+                    body: GraphHelper.serializeContent(content),
                     headers: new Headers(({ 'Content-Type' : 'application/json' })) 
                 }),
             callback
@@ -225,7 +226,7 @@ export class GraphRequest {
                 url,
                 {
                     method: RequestMethod.POST,
-                    body: content,
+                    body: GraphHelper.serializeContent(content),
                     headers: new Headers(({ 'Content-Type' : 'application/json'})) 
                  }),
             callback
@@ -239,7 +240,7 @@ export class GraphRequest {
                 url,
                 { 
                     method: RequestMethod.PUT,
-                    body: content,
+                    body: GraphHelper.serializeContent(content),
                     headers: new Headers({ 'Content-Type' : 'application/octet-stream' })
                 }),
             callback