I would like to be able to edit a file that has been selected for upload. I want to search and replace text in case absolute files should be made relative...
I notice in the File API I can do some of it, but I get a little stuck:
document.getElementById('exampleInputFile').onchange = function(event) {
var fileToLoad = event.target.files[0];
if (fileToLoad) {
var reader = new FileReader();
reader.onload = function(fileLoadedEvent) {
var textFromFileLoaded = fileLoadedEvent.target.result;
//Use logic to remove absolute files
//Upload S3
};
reader.readAsText(fileToLoad, 'UTF-8');
}
};
I am trying to figure out how now to convert that text to a proper File so that I can upload it to S3 using an existing api that expects something returned by: event.target.files[0] code above.
I do not want the server to handle any heavy lifting here if I can avoid it (files can easily be a few megabytes since they can be 3D models).
Assuming you know the url of the file when it lands in the S3 bucket, you can retrieve the file using a http.get, which will give you the contents of the (I assume plain text file). You can then parse that file and do whatever modification you need to do on the contents. If the file has changed, you can then write it back to the S3 bucket to replace the original file.
On AWS you can use Lambda to execute NodeJS code when an event is triggered (for example an upload to a specified bucket).
Related
I am trying to upload image on my website to add it to the database as base64 encoded string. The problem is I can not receive the file path to upload it by java. On the front-end I am using HTML and javascript, here is the HTML tag:
<div class="col-xs-6">
<label>passport image </label><input id="image-input" type="file"
placeholder="file">
</div>
in javascript I added:
document.getElementById("image-input").value;
The path of the image that arrives to me is 'C:\fakepath\IMAGE_NAME'.
I need a way to send the photo or it's path to the java code, how can I do this while I am not using jsf nor spring.
Some browsers have a security feature that prevents JavaScript from
knowing your file's local full path. It makes sense - as a client, you
don't want the server to know your local machine's filesystem.
I use the object FileReader on the input onchange event for your input
file type! This example uses the readAsDataURL function and for that
reason you should have an tag. The FileReader object also has
readAsBinaryString to get the binary data, which can later be used to
create the same file on your server
Example:
var input = document.getElementById("inputFile");
var fReader = new FileReader();
fReader.readAsDataURL(input.files[0]);
fReader.onloadend = function(event){
var img = document.getElementById("yourImgTag");
img.src = event.target.result;
}
try this ! using : replace
var imgpath = document.getElementById("image-input").value;
var newPath = imgpath .replace("C:\\fakepath\\", "")
I try to download a pdf file that has been previously encoded using base 64.
I try to download it from an anchor tag, as follows
Download;
The file is downloaded but when I try to open it I get a message that the file has damage or is corrupted.
Interestingly, if I change href to an encode image data, the file is downloaded and opened as expected.
I found this example http://jsfiddle.net/filixix/0816jdfq/ and I see that is changed from data:application/pdf;base64, to data:application/octet-stream;base64, I tried but I am getting the same result.
Update
I am encode the pdf file as follows
const element = document.querySelector('#file'); // input type file
element.addEventListener('change', handleChange);
function handleChange() {
const file = this.files[0];
const fileReader = new FileReader();
fileReader.onload = function() {
const data = this.result;
// store data in database in a text type field
};
fileReader.readAsDataURL(file);
}
hen, in the view where I want to download the file, I realize the logic that I commented
General idea works as expected.
But I recommend You to keep pdf as file.
Cause Your corrupted pdf issue may be because of db field size (if You keep that string in db) or browser's request url limitations
So You're saying:
store data in database in a text type field
If You don't plan to move to file storage just change field type to: LONGBLOB
I am trying to upload a file using js file reader and AJAX to my server.
I used FileAPI and fileReader to read the file and convert it to string and then send it to the server via an AJAX request.
Here is my client side js code :
function upload() {
var file = document.getElementById('periodExcel').files[0];
if (file) {
console.log(file);
var reader = new FileReader();
reader.readAsText(file, file.type);
console.log(reader);
reader.onload = uploadAndRun;
}
}
function uploadAndRun(event) {
console.log(event);
var result = event.target.result;
$('#js').html(result);
var fileName = document.getElementById('periodExcel').files[0].name; //Should be 'picture.jpg'
$.post('./upload.php', {data: result, name: fileName}, function(result2){
$('#php').html(result2);
});
}
Here is the upload php script:
file_put_contents('upload/' . $_POST['name'], $_POST['data']);
it just write the file using php file_put_contents function.
My problem is that the uploaded file is corrupted and has a different size than the original file (it is larger).
I tried to use php file_get_contents function to read the same file and write it again using file_put_contents and the result file was fine and same as the original one.
I then tried to compare the two strings (the one that comes from the file reader and the one that comes from file_get_contents ) and compares the two strings using strcmp, that gives me that the string that come from the fileReader is larger than the one comes from file_get_contents.
So, what is the problem with my code and how to use the FileReader to upload file in this way while using readAsText function.
You are using the wrong collection in PHP. To access uploaded file stream use $_FILES.
See here:
http://php.net/manual/en/reserved.variables.files.php
and here: http://php.net/manual/en/features.file-upload.post-method.php
In short, PHP runtime takes care of reading the upload stream from the HTTP request, stores it locally in a temp folder and exposes the above map for you to access the temp file and possibly move it to another location (or do whatever else you need to do with it).
I have a question about the File API and uploading files in JavaScript and how I should do this.
I have already utilized a file uploader that was quite simple, it simply took the files from an input and made a request to the server, the server then handled the files and uploaded a copy file on the server in an uploads directory.
However, I am trying to give people to option to preview a file before uploading it. So I took advantage of the File API, specifically the new FileReader() and the following readAsDataURL().
The file object has a list of properties such as .size and .lastModifiedDate and I added the readAsDataURL() output to my file object as a property for easy access in my Angular ng-repeat().
My question is, it occurred to me as I was doing this that I could store the dataurl in a database rather than upload the actual file? I was unsure if modifying the File data directly with it's dataurl as a property would affect its transfer.
What is the best practice? Is it better to upload a file or can you just store the dataurl and then output that, since that is essentially the file itself? Should I not modify the file object directly?
Thank you.
Edit: I should also note that this is a project for a customer that wants it to be hard for users to simply take uploaded content from the application and save it and then redistribute it. Would saving the files are urls in a database mitigate against right-click-save-as behavior or not really?
There is more then one way to preview a file. first is dataURL with filereader as you mention. but there is also the URL.createObjectURL which is faster
Decoding and encoding to and from base64 will take longer, it needs more calculations, more cpu/memory then if it would be in binary format.
Which i can demonstrate below
var url = 'https://upload.wikimedia.org/wikipedia/commons/c/cc/ESC_large_ISS022_ISS022-E-11387-edit_01.JPG'
fetch(url).then(res => res.blob()).then(blob => {
// Simulates a file as if you where to upload it throght a file input and listen for on change
var files = [blob]
var img = new Image
var t = performance.now()
var fr = new FileReader
img.onload = () => {
// show it...
// $('body').append(img)
var ms = performance.now() - t
document.body.innerHTML = `it took ${ms.toFixed(0)}ms to load the image with FileReader<br>`
// Now create a Object url instead of using base64 that takes time to
// 1 encode blob to base64
// 2 decode it back again from base64 to binary
var t2 = performance.now()
var img2 = new Image
img2.onload = () => {
// show it...
// $('body').append(img)
var ms2 = performance.now() - t2
document.body.innerHTML += `it took ${ms2.toFixed(0)}ms to load the image with URL.createObjectURL<br><br>`
document.body.innerHTML += `URL.createObjectURL was ${(ms - ms2).toFixed(0)}ms faster`
}
img2.src = URL.createObjectURL(files[0])
}
fr.onload = () => (img.src = fr.result)
fr.readAsDataURL(files[0])
})
The base64 will be ~3x larger. For mobile devices I think you would want to save bandwidth and battery.
But then there is also the latency of doing a extra request but that's where http 2 comes to rescue
I'm creating a Google Chrome extension at the moment and I was wondering if it's possible for it to both create JSON files to download (export) and create a button where users can make the extension open and parse JSON files that they have saved in their local file system or on a USB stick (import)?
The parsing of each JSON from the local file system would simply involve reading off each key-value pair and doing something with the data. It would only have to deal with strings, so nothing complicated.
**EDIT: **My question is not a duplicate of this one because I'm not interested in changing the user's download path. All I want is to enable them to, with their consent, download a file to their normal download directory (which Filesaver.js can do). Plus, that post says nothing about importing.
You can fake link to "download" imaginary array MyData or whatever,:
var MyArray = [elem1, elem2, ....];
var _myArray = JSON.stringify(MyArray , null, 4); //indentation in json format, human readable
var vLink = document.createElement('a'),
vBlob = new Blob([_myArray], {type: "octet/stream"}),
vName = 'watever_you_like_to_call_it.json',
vUrl = window.URL.createObjectURL(vBlob);
vLink.setAttribute('href', vUrl);
vLink.setAttribute('download', vName );
vLink.click();
this will export/download your array into json file named as vName variable.
If you wish to import/read file:
create input element (type=file) and make it invisible (here I'm having html element and then adding js listener in script)
<input type="file" id="importOrig" accept=".json" style="display:none"/>
script
importOrig.addEventListener("change", importFun, false);
make button fakeImp (or any element), that you can style as you wish and that will be used as trigger for importing event
fakeImp.onclick = function () {importOrig.click()}
import function (from listener)
function importFun(e) {
var files = e.target.files, reader = new FileReader();
reader.onload = _imp;
reader.readAsText(files[0]);
}
function _imp() {
var _myImportedData = JSON.parse(this.result);
//here is your imported data, and from here you should know what to do with it (save it to some storage, etc.)
......
importOrig.value = ''; //make sure to clear input value after every import
}