这篇文章将带您探讨如何使用Cloud Functions 实践Slack Slash Command，并与Google Knowledge Graph API 做整合。

流程解说

1.使用者在Slack频道当中执行/kg <想要搜寻的内容> Slash command
2. Slack发送带有payload的讯息至Cloud Functions endpoint 3. Cloud Functions发送带有使用者Query的请求至Knowledge Graph API 4 . Knowledge Graph API回传请求之讯息5. Cloud Functions把要回传之讯息打包成Slack的格式6. Cloud Functions回传讯息以及图片7.使用者看到回传结果

准备（API密钥+松弛令牌）

1.进入到APIs & Services
2.点选Create Credentials的API Key，创建一个API Key
3.创建完API KEY之后到Dashborad启用Knowledge Graph API Key
4.进入到所属Slack的Custom Integration页面https://xxxxx .slack.com/apps/manage/custom-integrations并点选Slash Commands
5.点选左边的Add Configuration
6. Choose a command栏位当中填入/kg后送出
7.送出后，请至页面下方的URL填入以下讯息(或是可以部署完Cloud Functions再填写)

//[YOUR_REGION]為使用者部署 Cloud Functions 的 Region
//[YOUR_PROJECT_ID]為使用者的 Project ID
https://[YOUR_REGION]-[YOUR_PROJECT_ID].cloudfunctions.net/kgSearch

8. 回到终端机并创建一个资料夹

$ mkdir ~/gcf_slack
$ cd ~/gcf_slack

部署到 Cloud Functions

1. 下载GCP的Node.js sample
2. 进到/nodejs-docs-samples/functions/helloworld/，把index.js 跟package.json 复制到刚刚的资料夹
3. 创建一个档案config.json，并填入以下资讯

   {
     "SLACK_TOKEN": "[YOUR_SLACK_TOKEN]", //[YOUR_SLACK_TOKEN] 在創立完 Slash command 之後，頁面下方產生的 Token
     "KG_API_KEY": "[YOUR_KG_API_KEY]" //[YOUR_KG_API_KEY] APIs & Service 裡剛剛創立的 Key value
   }
   

4. 进到index.js，删除所有内容并加入以下程式

   const config = require('./config.json');
   const googleapis = require('googleapis');
   const kgsearch = googleapis.kgsearch('v1');
   
   //當發一個 HTTP POST請求給 Cloud Functions 時會觸發
   exports.kgSearch = (req, res) => {
     return Promise.resolve()
       .then(() => {
         if (req.method !== 'POST') {
           const error = new Error('Only POST requests are accepted');
           error.code = 405;
           throw error;
         }
   
     // Verify that this request came from Slack
     verifyWebhook(req.body);
   
     // Make the request to the Knowledge Graph Search API
     return makeSearchRequest(req.body.text);
   })
   .then((response) => {
     // Send the formatted message back to Slack
     res.json(response);
   })
   .catch((err) => {
     console.error(err);
     res.status(err.code || 500).send(err);
     return Promise.reject(err);
   });
   };
   
   // 驗證 Slack token
   function verifyWebhook (body) {
     if (!body || body.token !== config.SLACK_TOKEN) {
       const error = new Error('Invalid credentials');
       error.code = 401;
       throw error;
     }
   }
   
    //把使用者的請求發送給 Knowledge Graph API
       function makeSearchRequest (query) {
         return new Promise((resolve, reject) => {
           kgsearch.entities.search({
             auth: config.KG_API_KEY,
             query: query,
             limit: 1
           }, (err, response) => {
             console.log(err);
             if (err) {
               reject(err);
               return;
             }
   
         // Return a formatted message
         resolve(formatSlackMessage(query, response));
       });
     });
   }
   
   //把資料轉換成 Slack 可以顯示的格式    
   function formatSlackMessage (query, response) {
     let entity;
   
     // Extract the first entity from the result list, if any
     if (response && response.itemListElement && response.itemListElement.length > 0) {
       entity = response.itemListElement[0].result;
     }
   
     // Prepare a rich Slack message
     // See https://api.slack.com/docs/message-formatting
     const slackMessage = {
       response_type: 'in_channel',
       text: `Query: ${query}`,
       attachments: []
     };
   
     if (entity) {
       const attachment = {
         color: '#3367d6'
       };
       if (entity.name) {
         attachment.title = entity.name;
         if (entity.description) {
           attachment.title = `${attachment.title}: ${entity.description}`;
         }
       }
       if (entity.detailedDescription) {
         if (entity.detailedDescription.url) {
           attachment.title_link = entity.detailedDescription.url;
         }
         if (entity.detailedDescription.articleBody) {
           attachment.text = entity.detailedDescription.articleBody;
         }
       }
       if (entity.image && entity.image.contentUrl) {
         attachment.image_url = entity.image.contentUrl;
       }
       slackMessage.attachments.push(attachment);
     } else {
       slackMessage.attachments.push({
         text: 'No results match your query...'
       });
     }
   
     return slackMessage;
   }
   

5. 进入到package.json，在dependencies 区块加入以下内容

   "googleapis": "^19.0.0",
   

6. $ gcloud beta functions deploy kgSearch --trigger-http
   

   测试

1. 执行以下指令进行测试

//[YOUR_REGION]為使用者部署 Cloud Functions 的 Region
//[YOUR_PROJECT_ID]為使用者的 Project ID
//[YOUR_SLACK_TOKEN]為Slack的使用 Token

$ curl -X POST "https://[YOUR_REGION]-[YOUR_PROJECT_ID].cloudfunctions.net/kgSearch" -H "Content-Type: application/json" --data '{"token":"[YOUR_SLACK_TOKEN]","text":"giraffe"}' -k

2. 查看Log 是否成功执行

$ gcloud beta functions logs read --limit 20

3. 在Slack 的任一频道送出以下内容，成功送出会显示长颈鹿的图片

/kg giraffe

清空资讯

1. 删除Cloud Functions 上的资讯

$ gcloud beta functions delete kgSearch

2. Disable 或是删除刚刚的Slash command

( 原文翻译Google Cloud。)