fix wechat bug

app/service/course/v5/wechat.js

@@ -51,12 +51,14 @@ class WechatService extends Service {
 
     if (!flag) {
       this.ctx.set('content-type', 'text/xml');
-      const xml = `<xml>
-      <ToUserName>${data.ToUserName}</ToUserName>
-      <FromUserName>${data.FromUserName}</FromUserName>
-      <CreateTime>${parseInt(new Date() / 1000)}</CreateTime>
-      <MsgType>transfer_customer_service</MsgType>
-  </xml>`;
+      let xml = {
+        MsgType: 'transfer_customer_service',
+        ToUserName: data.ToUserName,
+        FromUserName: data.FromUserName,
+        CreateTime: parseInt(new Date() / 1000),
+      };
+      const builder = new xml2js.Builder();
+      xml = builder.buildObject(xml);
       this.ctx.body = xml;
       ctx.logger.info('course_ctx: ' + JSON.stringify(this.ctx));
     }