如何将节点中生成的 docx 文件保存到 firebase 存储

Question

您好，我对 docxtemplater 很陌生，但我非常喜欢它的工作原理。现在我似乎能够生成一个新的 docx 文档如下：

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const {Storage} = require('@google-cloud/storage');
var PizZip = require('pizzip');
var Docxtemplater = require('docxtemplater');
admin.initializeApp();
const BUCKET = 'gs://myapp.appspot.com';

exports.test2 = functions.https.onCall((data, context) => {
// The error object contains additional information when logged with JSON.stringify (it contains a properties object containing all suberrors).
function replaceErrors(key, value) {
    if (value instanceof Error) {
        return Object.getOwnPropertyNames(value).reduce(function(error, key) {
            error[key] = value[key];
            return error;
        }, {});
    }
    return value;
}

function errorHandler(error) {
    console.log(JSON.stringify({error: error}, replaceErrors));

    if (error.properties && error.properties.errors instanceof Array) {
        const errorMessages = error.properties.errors.map(function (error) {
            return error.properties.explanation;
        }).join("\n");
        console.log('errorMessages', errorMessages);
        // errorMessages is a humanly readable message looking like this :
        // 'The tag beginning with "foobar" is unopened'
    }
    throw error;
}


let file_name = 'example.docx';// this is the file saved in my firebase storage
const File = storage.bucket(BUCKET).file(file_name);
const read = File.createReadStream();

var buffers = [];
readable.on('data', (buffer) => {
  buffers.push(buffer);
});

readable.on('end', () => {
  var buffer = Buffer.concat(buffers);  
  var zip = new PizZip(buffer);
  var doc;
  try {
      doc = new Docxtemplater(zip);
      doc.setData({
    first_name: 'Fred',
    last_name: 'Flinstone',
    phone: '0652455478',
    description: 'Web app'
});
try {
   
    doc.render();
 doc.pipe(remoteFile2.createReadStream());

}
catch (error) {
    errorHandler(error);
}

  } catch(error) {
      errorHandler(error);
  }

});
});

我的问题是我不断收到 doc.pipe is not a function 的错误。我对 nodejs 很陌生，但是有没有办法让 doc.render() 之后新生成的文档直接保存到 firebase 存储？

Answer 1

查看 doc 的类型，我们发现它是一个 Docxtemplater 对象，并且发现 doc.pipe 不是 class 的函数。要从 Docxtemplater 中获取文件，我们需要使用 doc.getZip() 到 return 文件（这将是 JSZip v2 或 Pizzip 实例，具体取决于什么我们传递给构造函数）。现在我们有了 zip 的对象，我们需要生成 zip 的二进制数据——这是使用 generate({ type: 'nodebuffer' }) 完成的（以获得包含数据的 Node.JS Buffer）。不幸的是，因为 docxtemplater 库不支持 JSZip v3+，我们无法使用 generateNodeStream() 方法来获取要与 pipe().[=40= 一起使用的流]

有了这个缓冲区，我们可以将它重新上传到云存储，或者将它发送回调用该函数的客户端。

第一个方案实现起来比较简单：

import { v4 as uuidv4 } from 'uuid';
/* ... */

const contentBuffer = doc.getZip()
      .generate({type: 'nodebuffer'});
const targetName = "compiled.docx";
  
const targetStorageRef = admin.storage().bucket()
  .file(targetName);
await targetStorageRef.save(contentBuffer);

// send back the bucket-name pair to the caller
return { bucket: targetBucket, name: targetName };

然而，将文件本身发送回客户端并不容易，因为这涉及切换到使用 HTTP Event Function (functions.https.onRequest) because a Callable Cloud Function 只能 return JSON 兼容的数据。这里我们有一个中间件函数，它接受一个可调用的处理函数，但支持 return 将二进制数据发送到客户端。

import * as functions from "firebase-functions";
import * as admin from "firebase-admin";
import corsInit from "cors";

admin.initializeApp();

const cors = corsInit({ origin: true }); // TODO: Tighten

function callableRequest(handler) {
  if (!handler) {
    throw new TypeError("handler is required");
  }
  
  return (req, res) => {
    cors(req, res, (corsErr) => {
      if (corsErr) {
        console.error("Request rejected by CORS", corsErr);
        res.status(412).json({ error: "cors", message: "origin rejected" });
        return;
      }

      // for validateFirebaseIdToken, see https://github.com/firebase/functions-samples/blob/main/authorized-https-endpoint/functions/index.js
      validateFirebaseIdToken(req, res, () => { // validateFirebaseIdToken won't pass errors to `next()`

        try {
          const data = req.body;
          const context = {
            auth: req.user ? { token: req.user, uid: req.user.uid } : null,
            instanceIdToken: req.get("Firebase-Instance-ID-Token"); // this is used with FCM
            rawRequest: req
          };

          let result: any = await handler(data, context);

          if (result && typeof result === "object" && "buffer" in result) {
            res.writeHead(200, [
              ["Content-Type", res.contentType],
              ["Content-Disposition", "attachment; filename=" + res.filename]
            ]);
            
            res.end(result.buffer);
          } else {
            result = functions.https.encode(result);

            res.status(200).send({ result });
          }
        } catch (err) {
          if (!(err instanceof HttpsError)) {
            // This doesn't count as an 'explicit' error.
            console.error("Unhandled error", err);
            err = new HttpsError("internal", "INTERNAL");
          }

          const { status } = err.httpErrorCode;
          const body = { error: err.toJSON() };

          res.status(status).send(body);
        }
      });
    });
  };
})

functions.https.onRequest(callableRequest(async (data, context) => {
  /* ... */

  const contentBuffer = doc.getZip()
      .generate({type: "nodebuffer"});
  const targetName = "compiled.docx";

  return {
    buffer: contentBuffer,
    contentType: "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    filename: targetName
  }
}));

在您当前的代码中，有许多奇怪的段，您在不同的范围内嵌套了 try-catch 块和变量。为了帮助解决这个问题，我们可以利用 File#download() 和 return 中的 Promise 来解析 Node.JS Buffer 和 [=32= 中的文件内容] 那 return 是一个 Promise，在给定的 Buffer 上传时解析。

将这些合并在一起以重新上传到云存储得到：

// This code is based off the examples provided for docxtemplater
// Copyright (c) Edgar HIPP [Dual License: MIT/GPLv3]

import * as functions from "firebase-functions";
import * as admin from "firebase-admin";
import PizZip from "pizzip";
import Docxtemplater from "docxtemplater";

admin.initializeApp();

// The error object contains additional information when logged with JSON.stringify (it contains a properties object containing all suberrors).
function replaceErrors(key, value) {
  if (value instanceof Error) {
    return Object.getOwnPropertyNames(value).reduce(
      function (error, key) {
        error[key] = value[key];
        return error;
      },
      {}
    );
  }
  return value;
}

function errorHandler(error) {
  console.log(JSON.stringify({ error: error }, replaceErrors));

  if (error.properties && error.properties.errors instanceof Array) {
    const errorMessages = error.properties.errors
      .map(function (error) {
        return error.properties.explanation;
      })
      .join("\n");
    console.log("errorMessages", errorMessages);
    // errorMessages is a humanly readable message looking like this :
    // 'The tag beginning with "foobar" is unopened'
  }
  throw error;
}

exports.test2 = functions.https.onCall(async (data, context) => {
  const file_name = "example.docx"; // this is the file saved in my firebase storage
  const templateRef = await admin.storage().bucket()
      .file(file_name);
  const template_content = (await templateRef.download())[0];
  const zip = new PizZip(template_content);

  let doc;
  try {
    doc = new Docxtemplater(zip);
  } catch (error) {
    // Catch compilation errors (errors caused by the compilation of the template : misplaced tags)
    errorHandler(error);
  }

  doc.setData({
    first_name: "Fred",
    last_name: "Flinstone",
    phone: "0652455478",
    description: "Web app",
  });

  try {
    doc.render();
  } catch (error) {
    errorHandler(error);
  }

  const contentBuffer = doc.getZip().generate({ type: "nodebuffer" });

  // do something with contentBuffer
  // e.g. reupload to Cloud Storage
  const targetStorageRef = admin.storage().bucket().file("compiled.docx");
  await targetStorageRef.save(contentBuffer);

  return { bucket: targetStorageRef.bucket.name, name: targetName };
});

除了向调用者return发送一个桶名对，您还可以考虑return向调用者发送一个访问URL。这可能是 signed url that can last for up to 7 days, a download token URL (like getDownloadURL(), ) that can last until the token is revoked, Google Storage URI (gs://BUCKET_NAME/FILE_NAME) (not an access URL, but can be passed to a client SDK that can access it if the client passes storage security rules) or access it directly using its public URL（在文件被标记为 public 之后）。

根据以上代码，您应该可以自己直接合并 return 文件。

如何将节点中生成的 docx 文件保存到 firebase 存储

How to get an docx file generated in node saved to firebase storage

node.js

google-cloud-storage

firebase

google-cloud-functions

docxtemplater