Develop Reference

Display file.pdf As a Blob

I am working on different ways of displaying a PDF to get better on a project at work. I am able to insert a url to a PDF into an iframe element and it displays the PDF fine. Sometimes we have a use case where the front end receives a pdf as application/pdf instead of a url in a json object.
For this, I turn the application/pdf into a blob and create a url for the blob. This worked great on everything except Android, so I am testing out some methods with iFrame.
I would like to take this sample pdf http://www.pdf995.com/samples/pdf.pdf, turn it into a blob, and insert the blob url in the src of an iframe element for the purposes of testing blobs as iframe sources on Android Chrome browsers.
function App() {
const samplePdf = "http://www.pdf995.com/samples/pdf.pdf"
const blob = new Blob([samplePdf], { type: 'application/pdf' });
const url = URL.createObjectURL(blob)
return (
<>
<h1>iFrame Rendering of PDF Blob</h1>
<iframe title="pdf" src={url} style={{ height: '1250px', width: '100%' }}></iframe>
</>
);
}
export default App;
This is what renders in the React app
What am I missing to get the content of the pdf to display? React is not a requirement, just seemed an easy way to start a quick practice project.

You need the data to construct the blob while the URL just points to the data you need. Let's go & get it:
const getLocalPdfUrl = async () => {
const url = 'http://www.pdf995.com/samples/pdf.pdf';
const response = await fetch(url);
const blob = await response.blob();
return URL.createObjectURL(blob);
};
This function returns a Promise that will (hopefully) resolve with the URL you can use to construct the iframe. It's async, so, don't forget to wait for the promise to resolve.
Testing note
Fetching external resources from the frontend is restricted by CORS, so, pdf995.com's link will not work. It's also not a trivial task to find a dummy PDF document that would allow fetching itself from the FE.
To test if it works, I'd propose to place the PDF file in the /public folder (or similar) & serve it on the same locslhost as the app.

iframe and PDF blob not rendering in Safari

We have a ReactJS web app which uses an iframe to embed PDF in the page. We download the PDF as a byte array, then store it as a blob URL. It works in all browsers except Safari. We use createURLObject which creates a local url like blob:http://domain/guid.
If I grab this URL and open it in another tab, it shows the PDF. Not in Safari. It redirects to favorites with a random Guid and fails.
It seems Safari has issues with blobs or PDFs.
I tried changing it from a blob url to a data URL using a file reader. Only difference is that Safari can render the data url in another tab but not in an iframe.
The iframe loads but the body is empty with the message 'no supported plugin found'. Im running out of idea and think Safari just sucks
downloadPDf(customerId) {
this.api.downloadContract(customerId)
.then(response => {
const pdfData = new Blob(response.data.conent, 'application/pdf');
reader.onload = () => {
this.setState({dataUrl : reader.result });
}
reader.readAsDataURL(pdf);
}
Then in the JSX:
<iframe src={this.state.dataUrl} .... />
Once the file reader is loaded, the result will have a data URL containing the RAW data for the PDF.
It looks like something like this: data:application/pdf:byte64:<FILE_CONTENT>
This wont render in the iframe, but pasting it into a new tab will actually render the PDF correctly.
Our original code relied on Blob URLS which is like this:
downloadPDf(customerId) {
this.api.downloadContract(customerId)
.then(response => {
const pdfData = new Blob(response.data.conent, 'application/pdf');
const dataUrl = window.URL.CreateURLObject(blob);
}
This will create a local blob url which looks like: blob:http://localhost/
Pasting this into another tab does not work in Safari. It works in Edge, Chrome, and FireFox.
The downside of using the data URL is the file reader and a callback.

Write image file to Firebase Storage from HTTP function

I am trying to write an image Firebase Storage via a Cloud Function (for more suitable write access).
My current attempt is to read the file object on the client, send it (the data) to an http firebase function, and then save it to storage from there. After saving the file successfully, I try using the download url as an img src value, but the file does not display. I also see an error in the Storage console (Error loading preview) when attempting to view the file.
If I save the data in Storage as base64, I can copy the contents of the file into the img src attribute, and it displays fine. However, I'd like to simply use the download URL as I could do if I just uploaded the image via the client SDK or directly via the console.
In the client, I'm simply using FileReader to read the uploaded file for sending. I've tried all the ways of reading it (readAsText,readAsBinaryString, readAsDataURL, readAsArrayBuffer), but none seem to solve the issue.
Here is how I am uploading the file via the Firebase Function:
import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
import * as path from 'path';
import * as os from 'os';
import * as fs from 'fs-extra';
export default functions.https.onCall(async(req, context) => {
const filename = req.filename;
const bucket = admin.storage().bucket(environment.bucket)
const temp_filename = filename;
const temp_filepath = path.join(os.tmpdir(), temp_filename);
await fs.outputFile(temp_filepath, req.data, {});
// Upload.
await bucket.upload(temp_filepath, {destination: 'logos'})
.then((val) => {})
.catch((err) => {});
});
This uploads the file successfully, however, the Download URL does not work when used as the img src attribute.
One thing I have noticed is that when using the client SDK to send a file (via AngularFireStorage), the payload is the raw png contents. E.g. a snippet of the file:
PNG
IHDRÈÈ­X®¤IDATx^í]
Eµ¾·{&1,!dù»*yVQ#PTEDPA>ÊâC\P"ÈÄ"
F}òIW÷üCL#BÉL÷}
....
However, reading the file as text does not yield this encoding. I have tried several other encodings.
Any help would be immensely appreciated.
Edit
Here is what I mean about using the download URL:
<img alt='logo' src='https://firebasestorage.googleapis.com/v0/b/y<project-name>/o/logos%2FAnM65PlBGluoIzdgN9F5%2Fuser.png?alt=media&token=<token>' />
The above src url is the one provided in the Firebase Storage console when clicking on the file. It is labeled as 'Download URL' (I believe this is the one retrieved by calling getDownloadUrl() via the sdk).
When using AngularFireStorage to put the file in storage, the Download URL will work. When I say it 'will work', I mean the image will display properly. When using FileReader to pass the data to an http cloud function to upload (as seen above), the image will not display. In other words, after uploading the file via the backend, the download url does in fact provide what was uploaded, it's just not in a format that an img tag can display.
One possible issue may be that I am not getting the encoding correct when using FileReader readAsText. Here is what I am doing with FileReader:
const reader = new FileReader();
reader.onloadend = () => {
firebase.functions().httpsCallable('http_put_logo')(reader.result);
};
// Have tried various encodings here, as well as all reader methods.
reader.readAsText(file);
Edit 2
All of the discussion on this question so far seems to be around correctly getting the download URL. I'm not sure if Firebase docs have this information, but the download URL is available in the Storage console. I'm simply copying and pasting that URL to for testing purposes at the moment.
The reason why I am doing this is because I plan to save these image URLs in the DB since they are going to be frequently used and publicly readable. So, I'm not going to use the getDownLoadURL() method to fetch these images, I'm simply just going to link to them directly in img tags.
Here is an image of my console to see what I mean (bottom right):
You just have to click it and copy it. You can then open it in a browser tab, download it, use it as a src value, etc.
Edit 3
Here is an image of what the request payload looks like when using the client sdk:
Here is when I read the file as text and send to backend for upload:
Notice there are differences in the payloads. That's why I'm uncertain if I'm properly reading the file or encoding it incorrectly.

What part of your code is taking care of getting the URL? I recently used a similar approach to uploading images to Firebase Storage using cloud functions. What worked best for me was to execute a different function to get the URL after the upload is complete. Something like this:
const bucket = admin.storage().bucket(environment.bucket)
const temp_filename = filename;
const temp_filepath = path.join(os.tmpdir(), temp_filename);
await fs.outputFile(temp_filepath, req.data, {});
// Upload.
await bucket.upload(temp_filepath, {destination: 'images'})
.then((val) => {retrieveUrl(temp_filename)})
.catch((err) => {});
retrieveUrl = (imageName) => {
const storage = firebase.storage();
storage.ref(`/images/${imageName}.jpg`).getDownloadURL()
.then( url => {
/*Save the url to a variable or attach it directly to the src of your image, depending on the structure of your project*/
})
.catch(err => console.log(err));
}
Keep in mind that you need to install firebase in your project in order to call firebase.storage.

Blob name issue with new tab in chrome and firefox [duplicate]

In my Vue app I receive a PDF as a blob, and want to display it using the browser's PDF viewer.
I convert it to a file, and generate an object url:
const blobFile = new File([blob], `my-file-name.pdf`, { type: 'application/pdf' })
this.invoiceUrl = window.URL.createObjectURL(blobFile)
Then I display it by setting that URL as the data attribute of an object element.
<object
:data="invoiceUrl"
type="application/pdf"
width="100%"
style="height: 100vh;">
</object>
The browser then displays the PDF using the PDF viewer. However, in Chrome, the file name that I provide (here, my-file-name.pdf) is not used: I see a hash in the title bar of the PDF viewer, and when I download the file using either 'right click -> Save as...' or the viewer's controls, it saves the file with the blob's hash (cda675a6-10af-42f3-aa68-8795aa8c377d or similar).
The viewer and file name work as I'd hoped in Firefox; it's only Chrome in which the file name is not used.
Is there any way, using native Javascript (including ES6, but no 3rd party dependencies other than Vue), to set the filename for a blob / object element in Chrome?
[edit] If it helps, the response has the following relevant headers:
Content-Type: application/pdf; charset=utf-8
Transfer-Encoding: chunked
Content-Disposition: attachment; filename*=utf-8''Invoice%2016246.pdf;
Content-Description: File Transfer
Content-Encoding: gzip

Chrome's extension seems to rely on the resource name set in the URI, i.e the file.ext in protocol://domain/path/file.ext.
So if your original URI contains that filename, the easiest might be to simply make your <object>'s data to the URI you fetched the pdf from directly, instead of going the Blob's way.
Now, there are cases it can't be done, and for these, there is a convoluted way, which might not work in future versions of Chrome, and probably not in other browsers, requiring to set up a Service Worker.
As we first said, Chrome parses the URI in search of a filename, so what we have to do, is to have an URI, with this filename, pointing to our blob:// URI.
To do so, we can use the Cache API, store our File as Request in there using our URL, and then retrieve that File from the Cache in the ServiceWorker.
Or in code,
From the main page
// register our ServiceWorker
navigator.serviceWorker.register('/sw.js')
.then(...
...
async function displayRenamedPDF(file, filename) {
// we use an hard-coded fake path
// to not interfere with legit requests
const reg_path = "/name-forcer/";
const url = reg_path + filename;
// store our File in the Cache
const store = await caches.open( "name-forcer" );
await store.put( url, new Response( file ) );
const frame = document.createElement( "iframe" );
frame.width = 400
frame.height = 500;
document.body.append( frame );
// makes the request to the File we just cached
frame.src = url;
// not needed anymore
frame.onload = (evt) => store.delete( url );
}
In the ServiceWorker sw.js
self.addEventListener('fetch', (event) => {
event.respondWith( (async () => {
const store = await caches.open("name-forcer");
const req = event.request;
const cached = await store.match( req );
return cached || fetch( req );
})() );
});
Live example (source)
Edit: This actually doesn't work in Chrome...
While it does set correctly the filename in the dialog, they seem to be unable to retrieve the file when saving it to the disk...
They don't seem to perform a Network request (and thus our SW isn't catching anything), and I don't really know where to look now.
Still this may be a good ground for future work on this.
And an other solution, I didn't took the time to check by myself, would be to run your own pdf viewer.
Mozilla has made its js based plugin pdf.js available, so from there we should be able to set the filename (even though once again I didn't dug there yet).
And as final note, Firefox is able to use the name property of a File Object a blobURI points to.
So even though it's not what OP asked for, in FF all it requires is
const file = new File([blob], filename);
const url = URL.createObjectURL(file);
object.data = url;

In Chrome, the filename is derived from the URL, so as long as you are using a blob URL, the short answer is "No, you cannot set the filename of a PDF object displayed in Chrome." You have no control over the UUID assigned to the blob URL and no way to override that as the name of the page using the object element. It is possible that inside the PDF a title is specified, and that will appear in the PDF viewer as the document name, but you still get the hash name when downloading.
This appears to be a security precaution, but I cannot say for sure.
Of course, if you have control over the URL, you can easily set the PDF filename by changing the URL.

I believe Kaiido's answer expresses, briefly, the best solution here:
"if your original URI contains that filename, the easiest might be to simply make your object's data to the URI you fetched the pdf from directly"
Especially for those coming from this similar question, it would have helped me to have more description of a specific implementation (working for pdfs) that allows the best user experience, especially when serving files that are generated on the fly.
The trick here is using a two-step process that perfectly mimics a normal link or button click. The client must (step 1) request the file be generated and stored server-side long enough for the client to (step 2) request the file itself. This requires you have some mechanism supporting unique identification of the file on disk or in a cache.
Without this process, the user will just see a blank tab while file-generation is in-progress and if it fails, then they'll just get the browser's ERR_TIMED_OUT page. Even if it succeeds, they'll have a hash in the title bar of the PDF viewer tab, and the save dialog will have the same hash as the suggested filename.
Here's the play-by-play to do better:
You can use an anchor tag or a button for the "download" or "view in browser" elements
Step 1 of 2 on the client: that element's click event can make a request for the file to be generated only (not transmitted).
Step 1 of 2 on the server: generate the file and hold on to it. Return only the filename to the client.
Step 2 of 2 on the client:
If viewing the file in the browser, use the filename returned from the generate request to then invoke window.open('view_file/<filename>?fileId=1'). That is the only way to indirectly control the name of the file as shown in the tab title and in any subsequent save dialog.
If downloading, just invoke window.open('download_file?fileId=1').
Step 2 of 2 on the server:
view_file(filename, fileId) handler just needs to serve the file using the fileId and ignore the filename parameter. In .NET, you can use a FileContentResult like File(bytes, contentType);
download_file(fileId) must set the filename via the Content-Disposition header as shown here. In .NET, that's return File(bytes, contentType, desiredFilename);
client-side download example:
download_link_clicked() {
// show spinner
ajaxGet(generate_file_url,
{},
(response) => {
// success!
// the server-side is responsible for setting the name
// of the file when it is being downloaded
window.open('download_file?fileId=1', "_blank");
// hide spinner
},
() => { // failure
// hide spinner
// proglem, notify pattern
},
null
);
client-side view example:
view_link_clicked() {
// show spinner
ajaxGet(generate_file_url,
{},
(response) => {
// success!
let filename = response.filename;
// simplest, reliable method I know of for controlling
// the filename of the PDF when viewed in the browser
window.open('view_file/'+filename+'?fileId=1')
// hide spinner
},
() => { // failure
// hide spinner
// proglem, notify pattern
},
null
);

I'm using the library pdf-lib, you can click here to learn more about the library.
I solved part of this problem by using api Document.setTitle("Some title text you want"),
Browser displayed my title correctly, but when click the download button, file name is still previous UUID. Perhaps there is other api in the library that allows you to modify download file name.

How to download entire website from inside the website

I'm making a website, in which I want to offer the user to download the whole website (CSS and images included) for them to modify. I know I can download individual resources with
Click Me
but like I said, this only downloads one file, whereas I would like to download the entire website.
If it helps you visualise what I mean: in chrome, IE and Firefox you can press ctrl+s to download the entire website (make sure you save it as Web page, Complete.
Edit: I know I can create a .zip file that it will download, however doing so requires me to update it every time I make a change, which is something I'd rather not do, as I could potentially be making a lot of changes.

As I mention, it is better that you will have a cron job or something like this that once in a while will create you a zip file of all the desired static content.
If you insist doing it in javascript at the client side have a look at JSZip .
You still have to find a way to get the list of static files of the server to save.
For instance, you can create a txt file with each line is a link to a webpage static file.
you will have to iterate over this file and use $.get to get it's content.
something like this:
// Get list of files to save (either by GET request or hardcoded)
filesList = ["f1.json /echo/jsonp?name=1", "inner/f2.json /echo/jsonp?name=2"];
function createZip() {
zip = new JSZip();
// make bunch of requests to get files content
var requests = [];
// for scoping the fileName
_then = (fname) => data => ({ fileName: fname, data });
for (var file of filesList) {
[fileName, fileUrl] = file.split(" ");
requests.push($.get(fileUrl).then(_then(fileName)));
}
// When all finished
$.when(...requests).then(function () {
// Add each result to the zip
for (var arg of arguments) {
zip.file(arg.fileName, JSON.stringify(arg.data));
}
// Save
zip.generateAsync({ type: "blob" })
.then(function (blob) {
saveAs(blob, "site.zip");
});
});
}
$("#saver").click(() => {
createZip();
});
JSFiddle
Personally, I don't like this approach. But do as you prefer.