diff --git a/example/contact-bot.ts b/example/contact-bot.ts
new file mode 100644
index 0000000000000000000000000000000000000000..752071e92f320d8f77a19e4c30a35b6784e0803b
--- /dev/null
+++ b/example/contact-bot.ts
@@ -0,0 +1,86 @@
+/**
+ *
+ * Wechaty - Wechat for Bot
+ *
+ * Connecting ChatBots
+ * https://github.com/wechaty/wechaty
+ *
+ */
+import {
+    Config
+  , Contact
+  , Wechaty
+  , log
+} from '../'
+
+const welcome = `
+=============== Powered by Wechaty ===============
+-------- https://github.com/wechaty/wechaty --------
+
+Hello,
+
+I'm a Wechaty Botie with the following super powers:
+
+1. List all your contacts with weixn id & name
+
+__________________________________________________
+
+Hope you like it, and you are very welcome to
+upgrade me for more super powers!
+
+Please wait... I'm trying to login in...
+
+`
+
+console.log(welcome)
+const bot = Wechaty.instance({ profile: Config.DEFAULT_PROFILE })
+
+bot
+.on('login'	  , function(this, user) {
+  log.info('Bot', `${user.name()} logined`)
+  this.say('wechaty contact-bot just logined')
+  main()
+})
+.on('logout'	, user => log.info('Bot', `${user.name()} logouted`))
+.on('error'   , e => log.info('Bot', 'error: %s', e))
+.on('scan', (url, code) => {
+  if (!/201|200/.test(String(code))) {
+    let loginUrl = url.replace(/\/qrcode\//, '/l/')
+    require('qrcode-terminal').generate(loginUrl)
+  }
+  console.log(`${url}\n[${code}] Scan QR Code in above url to login: `)
+})
+
+bot.init()
+.catch(e => {
+  log.error('Bot', 'init() fail: %s', e)
+  bot.quit()
+  process.exit(-1)
+})
+
+async function main() {
+  const contactList = await Contact.findAll()
+
+  log.info('Bot', '#######################')
+  log.info('Bot', 'Contact number: %d\n', contactList.length)
+
+  const MAX = 17
+  for (let i = 0; i < contactList.length; i++ ) {
+    const contact = contactList[i]
+    await contact.ready()
+
+    if (!contact.weixin()) {
+      await contact.refresh()
+    }
+
+    log.info('Bot', 'Contact: %s: %s', contact.weixin(), contact.name())
+
+    if (i > MAX) {
+      log.info('Bot', 'Contact too many, I only show you the first %d ... ', MAX)
+      break
+    }
+  }
+
+  log.info('Bot', 'I will re-dump contact names after 7 second... ')
+  setTimeout(main, 7000)
+}
diff --git a/src/contact.ts b/src/contact.ts
index 53923744c5a686b029e6ed906ea0dd63d1711f6c..a65dbbcfde67d9b4b3b0847a7c0ca9b11c0acb36 100644
--- a/src/contact.ts
+++ b/src/contact.ts
@@ -53,6 +53,7 @@ export class Contact implements Sayable {
   private static pool = new Map<string, Contact>()
 
   private obj: ContactObj | null
+  private dirtyObj: ContactObj | null
   private rawObj: ContactRawObj
 
   constructor(public readonly id: string) {
@@ -89,6 +90,7 @@ export class Contact implements Sayable {
     }
   }
 
+  public weixin()    { return this.obj && this.obj.weixin || '' }
   public name()      { return UtilLib.plainText(this.obj && this.obj.name || '') }
   public remark()    { return this.obj && this.obj.remark }
   public stranger()  { return this.obj && this.obj.stranger }
@@ -100,6 +102,14 @@ export class Contact implements Sayable {
     return !!(this.obj && this.obj.id)
   }
 
+  public async refresh(): Promise<this> {
+    if (this.isReady()) {
+      this.dirtyObj = this.obj
+    }
+    this.obj = null
+    return this.ready()
+  }
+
   public async ready(contactGetter?: (id: string) => Promise<ContactRawObj>): Promise<this> {
     log.silly('Contact', 'ready(' + (contactGetter ? typeof contactGetter : '') + ')')
     if (!this.id) {
@@ -157,7 +167,10 @@ export class Contact implements Sayable {
     return selfId === userId
   }
 
-  public static findAll(query: ContactQueryFilter): Promise<Contact[]> {
+  public static findAll(query?: ContactQueryFilter): Promise<Contact[]> {
+    if (!query) {
+      query = { name: /.*/ }
+    }
     log.verbose('Cotnact', 'findAll({ name: %s })', query.name)
 
     const name = query.name
@@ -192,7 +205,7 @@ export class Contact implements Sayable {
     log.verbose('Contact', 'find(%s)', query.name)
 
     const contactList = await Contact.findAll(query)
-    if (!contactList || contactList.length < 1) {
+    if (!contactList || !contactList.length) {
       throw new Error('find not found any contact')
     }
     return contactList[0]