何處生成Firebase數據庫數據的PDF - 移動應用或Firebase託管網絡應用

Question

我有一個Android應用和一個Web應用（託管在Firebase託管上）。 Android應用會生成數據並將其保存到Firebase實時數據庫。 Android應用和網絡應用都可以查看數據。

何處是從Firebase數據庫生成PDF數據的最佳位置 - Android應用程序或Web應用程序（通過JavaScript，例如jsPDF）？它會保存在Firebase存儲中。

我認爲Android應用程序可以調用後端來生成PDF，並且指向PDF的鏈接將被髮送回Android應用程序。不過，Firebase是無服務器架構，所以似乎最好的解決方案是在Android應用上創建PDF，然後將其上傳到Firebase存儲...？

Answer 1

由於存在Firebase函數（Firebase Introduction），因此可以使用NodeJS以pdfkit（PDFKit）爲例創建PDfs。以下示例描述了一種在AccountCreation（Event）上生成PDF的方法，將其保存到存儲並通過郵件發送給用戶。所有這些都發生在Firebase服務器上。對於所有使用的圖書館不要忘記npm安裝它們並將它們包含到package.json中。一個棘手的部分是add the Firebase Admin SDK to your Server。另外，this幫了很多。說實話，這花了我幾個小時。所以不要請求細節！

const functions = require('firebase-functions'); 
const admin = require("firebase-admin"); 

const nodemailer = require('nodemailer'); 
const pdfkit = require('pdfkit'); 

const gmailEmail = 'yourmail@stackoverflow.com' 
const gmailPassword = 'test123.ThisisNoTSave' 
const mailTransport = nodemailer.createTransport(`smtps://${gmailEmail}:${gmailPassword}@smtp.gmail.com`); 

const serviceAccount = require("./youradminsdk.json"); 
//Save this file to your functions Project 

// Your company name to include in the emails 
const APP_NAME = 'My App'; 
const PROJECT_ID = "google-testproject"; 

admin.initializeApp({ 
    credential: admin.credential.cert(serviceAccount), 
    databaseURL: `https://${PROJECT_ID}.firebaseio.com`, 
    storageBucket: `${PROJECT_ID}.appspot.com` 
}); 

var config = { 
    projectId: `${PROJECT_ID}`, 
    keyFilename: './youradminsdk.json' 
}; 

const storage = require('@google-cloud/storage')(config); 
const datastore= require('@google-cloud/datastore')(config); 

// [START onCreateTrigger] 
exports.sendPDFMail = functions.auth.user().onCreate(event => { 
// [END onCreateTrigger] 

     // [START eventAttributes] 
     const doc = new pdfkit; 
     const user = event.data; // The Firebase user. 
     const email = user.email; // The email of the user. 
     const displayName = user.displayName; // The display name of the user. 
     // [END eventAttributes] 

     const bucket = storage.bucket(`${PROJECT_ID}.appspot.com`); 
     console.log(bucket); 
     const filename = Date.now() + 'output.pdf';      
     const file = bucket.file(filename); 
     const stream = file.createWriteStream({resumable: false}); 

     // Pipe its output to the bucket 
     doc.pipe(stream);    
     doc.fontSize(25).text('Some text with an embedded font!', 100, 100);   
     doc.end();   
     stream.on('finish', function() {     
      return sendPDFMail(email, displayName, doc); 
     }); 

     stream.on('error', function(err) { 
      console.log(err); 
     });   
     }) 
    ; 
    // [END sendPDFMail] 


    // Sends a welcome email to the given user. 
    function sendPDFMail(email, displayName, doc) { 
     const mailOptions = { 
      from: '"MyCompany" <noreply@firebase.com>', 
      to: email,   
     }; 

     mailOptions.subject = `Welcome to ${APP_NAME}!`; 
     mailOptions.text = `Hey ${displayName}!, Welcome to ${APP_NAME}. I hope you will enjoy our service.`; 
     mailOptions.attachments = [{filename: 'meinPdf.pdf', content: doc, contentType: 'application/pdf' }];   

     return mailTransport.sendMail(mailOptions).then(() => { 
      console.log('New welcome email sent to:', email); 
     }); 
    }