Develop Reference

How can I convert encoded base64 string uri (from native Android) to file in javascript?

I'd like to convert encoded base64 string uri to file in javascript.
Original uri is posted from android local file path. ("content://com.google.android.apps.docs.storage/document/*")
Below code is the progress of encoding uri and posting them written from JAVA(Android).
public static String fileUriToBase64(Uri uri, ContentResolver resolver) {
String encodedBase64 = "";
try {
byte[] bytes = readBytes(uri, resolver);
encodedBase64 = Base64.encodeToString(bytes, 0);
} catch (IOException e1) {
e1.printStackTrace();
}
return encodedBase64;
}
String originalUri = "content://com.google.android.apps.docs.storage/document/*";
String encodedUri = URLEncoder.encode(fileUriToBase64(originalUri, getContentResolver()));
webView.evaluateJavascript("javascript: " +"getCroppedImageUrl(\"" + "data:image/png;base64," + encodedUri +
"\")",null);
In webView, I can show that image uri via below code.
<img
:src="this.encodedUri"
id="img-test"
style="width: 150px; height: 150px"
/>
This webView made of Vue.JS.
When webView receive encodedUri, I want to post this image uri to server.
To decode this uri I use below code but it return error.
function base64ImageToBlob(str) {
const pos = str.indexOf(";base64,");
const type = str.substring(5, pos);
let decodedUri = decodeURI(str);
decodedUri = decodedUri.substr(pos + 8);
const imageContent = atob(decodedUri);
// create an ArrayBuffer and a view (as unsigned 8-bit)
const buffer = new ArrayBuffer(imageContent.length);
const view = new Uint8Array(buffer);
// fill the view, using the decoded base64
for (var n = 0; n < imageContent.length; n++) {
view[n] = imageContent.charCodeAt(n);
}
// convert ArrayBuffer to Blob
const blob = new Blob([buffer], { type: type });
return blob;
}
try {
url = base64ImageToBlob(url);
} catch (err) {
alert(err);
}
error message is 'InvalidCharacterError: Failed to execute 'atob' on 'Window': The string to be decoded is not correctly encoded'
How can I convert that uri to file?
Thank you for reading it.

Can't open zip file created from System.IO.Compression namespace

I'm trying to zip varying amounts of files so that one zip folder can be served to the user instead of them having to click multiple anchor tags. I am using the System.IO.Compression namespace in asp.net core 3.1 to create the zip folder.
Here is the code I'm using to create the Zip folder.
public IActionResult DownloadPartFiles(string[] fileLocations, string[] fileNames)
{
List<InMemoryFile> files = new List<InMemoryFile>();
for (int i = 0; i < fileNames.Length; i++)
{
InMemoryFile inMemoryFile = GetInMemoryFile(fileLocations[i], fileNames[i]).Result;
files.Add(inMemoryFile);
}
byte[] archiveFile;
using (MemoryStream archiveStream = new MemoryStream())
{
using (ZipArchive archive = new ZipArchive(archiveStream, ZipArchiveMode.Create, true))
{
foreach (InMemoryFile file in files)
{
ZipArchiveEntry zipArchiveEntry = archive.CreateEntry(file.FileName, CompressionLevel.Fastest);
using (Stream zipStream = zipArchiveEntry.Open())
{
zipStream.Write(file.Content, 0, file.Content.Length);
zipStream.Close();
}
}
archiveStream.Position = 0;
}
archiveFile = archiveStream.ToArray();
}
return File(archiveFile, "application/octet-stream");
}
The files I am trying to zip are stored remotely so I grab them with this block of code. The InMemoryFile is a class to group the file name and file bytes together.
private async Task<InMemoryFile> GetInMemoryFile(string fileLocation, string fileName)
{
InMemoryFile file;
using (HttpClient client = new HttpClient())
using (HttpResponseMessage response = await client.GetAsync(fileLocation))
{
byte[] fileContent = await response.Content.ReadAsByteArrayAsync();
file = new InMemoryFile(fileName, fileContent);
}
return file;
}
The DownloadPartFiles method is called using Ajax. I grab the remote paths to the files and their respective names using javascript and pass them into the Ajax call.
function downloadAllFiles() {
let partTable = document.getElementById("partTable");
let linkElements = partTable.getElementsByTagName('a');
let urls = [];
for (let i = 0; i < linkElements.length; i++) {
urls.push(linkElements[i].href);
}
if (urls.length != 0) {
var fileNames = [];
for (let i = 0; i < linkElements.length; i++) {
fileNames.push(linkElements[i].innerText);
}
$.ajax({
type: "POST",
url: "/WebOrder/DownloadPartFiles/",
data: { 'fileLocations': urls, 'fileNames': fileNames },
success: function (response) {
var blob = new Blob([response], { type: "application/zip" });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "PartFiles.zip";
link.click();
window.URL.revokeObjectURL(blob);
},
failure: function (response) {
alert(response.responseText);
},
error: function (response) {
alert(response.responseText);
}
});
}
}
Now the issue I keep running into is that I can't open the zip folder within Windows 10. Every time I try to open the zip folder using Windows or 7-zip I get an error message that the folder can't be opened or the folder is invalid. I've tried looking at various similar issues on stackoverflow, ie Invalid zip file after creating it with System.IO.Compression, but still can't figure out why this is.
Could it be the encoding? I found that Ajax expects its responses to be encoded UTF-8 and when I view the zip file using notepad++ with UTF-8 I see that there are � characters indicating corruption.
Any thoughts on this would be helpful. Let me know if more information is needed.
If one of the corrupt zip files is needed I can provide that as well.
Edit:
I have since changed my method of receiving the byte array in javascript. I am using a XMLHttpRequest to receive the byte array.
var parameters = {};
parameters.FileLocations = urls;
parameters.FileNames = fileNames;
var xmlhttp = new XMLHttpRequest();
xmlhttp.open("POST", "/WebOrder/DownloadPartFiles/", true);
xmlhttp.setRequestHeader("Content-Type", "application/json");
xmlhttp.responseType = "arraybuffer";
xmlhttp.onload = function (oEvent) {
var arrayBuffer = xmlhttp.response;
if (arrayBuffer) {
var byteArray = new Uint8Array(arrayBuffer);
var blob = new Blob([byteArray], { type: "application/zip" });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "PartFiles.zip";
link.click();
window.URL.revokeObjectURL(blob);
}
}
xmlhttp.send(JSON.stringify(parameters));
From what I read, Ajax is not the best for receiving byte arrays and binary data. With this method I was able to open one of the zip file with 7-zip, but not Windows, however, one of the files within the archive was showing as a size of 0KB and couldn't be opened. The other three files in the archive were fine. Other zip folders with different files could not be opened at all though.

After some time I found a post that was able to fix my issue, Create zip file from byte[]
From that post this is the revised method I'm using to create a zip folder with files in it.
public IActionResult DownloadPartFiles([FromBody] FileRequestParameters parameters)
{
List<InMemoryFile> files = new List<InMemoryFile>();
for (int i = 0; i < parameters.FileNames.Length; i++)
{
InMemoryFile inMemoryFile = GetInMemoryFile(parameters.FileLocations[i], parameters.FileNames[i]).Result;
files.Add(inMemoryFile);
}
byte[] archiveFile = null;
using (MemoryStream archiveStream = new MemoryStream())
{
using (ZipArchive archive = new ZipArchive(archiveStream, ZipArchiveMode.Create, true))
{
foreach (InMemoryFile file in files)
{
ZipArchiveEntry zipArchiveEntry = archive.CreateEntry(file.FileName, CompressionLevel.Optimal);
using (MemoryStream originalFileStream = new MemoryStream(file.Content))
using (Stream zipStream = zipArchiveEntry.Open())
{
originalFileStream.CopyTo(zipStream);
}
}
}
archiveFile = archiveStream.ToArray();
}
return File(archiveFile, "application/octet-stream");
}
I still don't know why the previous method was having issues so if anyone knows the answer to that in the future I'd love to know.

convert blob to Excel file and download, file cannot be open

I have an api which return below response, which contain the excel file content.
So now I need to convert them into excel file and download for the user.
Here is the api function
[HttpGet]
[IgnoreAntiforgeryToken]
public async Task<IActionResult> DownloadLoadedTrnFile(string S3Path)
{
try
{
string bucket = "taurus-" + GetEnvironmentSettings() + "-trn";
string fileName = "";
string[] fileStr = S3Path.Split('-');
if (fileStr.Count() > 0)
{
fileName = fileStr.Last();
}
Stream responseStream = await _imageStore.GetImage(bucket, S3Path);
if (responseStream == null)
return NotFound();
using (MemoryStream ms = new MemoryStream())
{
responseStream.CopyTo(ms);
var finalResult = File(System.Text.UTF8Encoding.UTF8.GetString(ms.ToArray()), MimeTypesMap.GetMimeType(S3Path), fileName);
return Ok(finalResult);
}
}
catch (Exception ex)
{
return StatusCode(500, "Error in downloading file.");
}
}
public async Task<Stream> GetImage(string bucketName, string objectKey)
{
GetObjectRequest originalRequest = new GetObjectRequest
{
BucketName = bucketName,
Key = objectKey
};
try
{
GetObjectResponse response = await S3Client.GetObjectAsync(originalRequest);
// AWS HashStream doesn't support seeking so we need to copy it back to a MemoryStream
MemoryStream outputStream = new MemoryStream();
response.ResponseStream.CopyTo(outputStream);
outputStream.Position = 0;
return outputStream;
}
catch (AmazonS3Exception ex)
{
// Not found if we get an exception
return null;
}
}
I have such function in the front-end as below,
function saveTextAsFile(data, filename, contentType) {
if (!data) {
console.error('Console.save: No data')
toastr.error("No data received from server");
return;
}
if (!filename) filename = 'noname.xlsx';
var blob = new Blob([s2ab(atob(data))], {
type: contentType
});
var a = document.createElement("a");
a.href = URL.createObjectURL(blob);
a.download = filename;
a.click();
}
and function
function s2ab(s) {
var buf = new ArrayBuffer(s.length);
var view = new Uint8Array(buf);
for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
return buf;
}
This function is working fine with excel that only has normal text. However, this excel i am trying to download, it has rich content such as color border, dropdown, multiple sheets.
When I try to use this same function to download the excel file, it throw me this error:
To help you more understand my problem, here is t he API HTTP CAll
I have try to search solution online but there is no luck. I actually do not understand what is the problem here. Anything will help thanks.

Thanks for all the replies and make my head around a little bit finally I fixed this issue.
Well, found the problem with it is because in the API I wrap that inside UTF-8. however, it (Excel) shouldn't be wrapped in UTF-8. only If I was downloading a csv file.
var finalResult = File(System.Text.UTF8Encoding.UTF8.GetString(ms.ToArray()),
MimeTypesMap.GetMimeType(S3Path), fileName);
Changed to
var finalResult = File(ms.ToArray(), MimeTypesMap.GetMimeType(S3Path), fileName);

Download file from FileStream return using React

Hi I have a web api like in the below picture - returning HttpResponseMessage, I am retutning fileStream as content of it, when I am trying to retrieve or log it on console as console.log(response.data)
it shows some other information but not the stream information or array or anything of that sort. Can somebody please help me how can I read or download file that's returned as stream or FileStream using React.
I am not using jQuery. Any help please, a link or something of that sort. I could able to download the file using byte array but need to implement using FileStream, any help please?
[EnableCors("AnotherPolicy")]
[HttpPost]
public HttpResponseMessage Post([FromForm] string communityName, [FromForm] string files) //byte[]
{
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
var removedInvalidCharsFromFileName = removeInvalidCharsFromFileName(files);
var tFiles = removedInvalidCharsFromFileName.Split(',');
string rootPath = Configuration.GetValue<string>("ROOT_PATH");
string communityPath = rootPath + "\\" + communityName;
byte[] theZipFile = null;
FileStreamResult fileStreamResult = null;
using (MemoryStream zipStream = new MemoryStream())
{
using (ZipArchive zip = new ZipArchive(zipStream, ZipArchiveMode.Create, true))
{
foreach (string attachment in tFiles)
{
var zipEntry = zip.CreateEntry(attachment);
using (FileStream fileStream = new FileStream(communityPath + "\\" + attachment, FileMode.Open))
using (Stream entryStream = zipEntry.Open())
{
fileStream.CopyTo(entryStream);
}
}
}
theZipFile = zipStream.ToArray();
fileStreamResult = new FileStreamResult(zipStream, "application/zip") { FileDownloadName = $"{communityName}.zip" };
var i = zipStream.Length;
zipStream.Position = 0;
var k= zipStream.Length;
result.Content = new StreamContent(zipStream);
result.Content.Headers.ContentType =
new MediaTypeHeaderValue("application/zip");
}
//return theZipFile;
return result;
}

Finally implemented by using the FileStreamResult as well maybe some people would be needed this, here is my API code and then I made call to the post method using axios, so here is my React code. In the axios call responseType becomes arraybuffer and the in the blob declaration it becomes the application/octet-stream type, Hence it completes everything, as I have imported the file-saver, I could able to use saveAs method of it. Finally after many efforts and hearing the screaming from PM, yes it is achieved - but that's the life of any Software Programmer.
Here is Web Api code C#:
[EnableCors("AnotherPolicy")]
[HttpPost]
public FileStreamResult Post([FromForm] string communityName, [FromForm] string files) //byte[]
{
var removedInvalidCharsFromFileName = removeInvalidCharsFromFileName(files);
var tFiles = removedInvalidCharsFromFileName.Split(',');
string rootPath = Configuration.GetValue<string>("ROOT_PATH");
string communityPath = rootPath + "\\" + communityName;
MemoryStream zipStream = new MemoryStream();
using (ZipArchive zip = new ZipArchive(zipStream, ZipArchiveMode.Create, true))
{
foreach (string attachment in tFiles)
{
var zipEntry = zip.CreateEntry(attachment);
using (FileStream fileStream = new FileStream(communityPath + "\\" + attachment, FileMode.Open))
{
using (Stream entryStream = zipEntry.Open())
{
fileStream.CopyTo(entryStream);
}
}
}
}
zipStream.Position = 0;
return File(zipStream, "application/octet-stream");
}
Then my client side React code is here:
handleDownload = (e) => {
e.preventDefault();
var formData = new FormData();
formData.append('communityname', this.state.selectedCommunity);
formData.append('files', JSON.stringify(this.state['checkedFiles']));
//let env='local';
let url = clientConfiguration['filesApi.local'];
//let tempFiles = clientConfiguration[`tempFiles.${env}`];
//alert(tempFiles);
axios({
method: 'post',
responseType: 'arraybuffer', //Force to receive data in a Blob Format
url: url,
data: formData
})
.then(res => {
let extension = 'zip';
let tempFileName = `${this.state['selectedCommunity']}`
let fileName = `${tempFileName}.${extension}`;
const blob = new Blob([res.data], {
type: 'application/octet-stream'
})
saveAs(blob, fileName)
})
.catch(error => {
console.log(error.message);
});
};
this event is called when button is clicked or form submitted. Thanks for all the support the SO has given - thanks a lot.

Converting byte array output into Blob corrupts file

I am using the Office Javascript API to write an Add-in for Word using Angular.
I want to retrieve the Word document through the API, then convert it to a file and upload it via POST to a server.
The code I am using is nearly identical to the documentation code that Microsoft provides for this use case: https://dev.office.com/reference/add-ins/shared/document.getfileasync#example---get-a-document-in-office-open-xml-compressed-format
The server endpoint requires uploads to be POSTed through a multipart form, so I create a FormData object on which I append the file (a blob) as well as some metadata, when creating the $http call.
The file is being transmitted to the server, but when I open it, it has become corrupted and it can no longer be opened by Word.
According to the documentation, the Office.context.document.getFileAsync function returns a byte array. However, the resulting fileContent variable is a string. When I console.log this string it seems to be compressed data, like it should be.
My guess is I need to do some preprocessing before turning the string into a Blob. But which preprocessing? Base64 encoding through atob doesn't seem to be doing anything.
let sendFile = ( fileContent ) => {
let blob = new Blob([fileContent], { type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' }),
fd = new FormData();
blob.lastModifiedDate = new Date();
fd.append('file', blob, 'uploaded_file_test403.docx');
fd.append('case_id', caseIdReducer.data());
$http.post('/file/create', fd, {
transformRequest: angular.identity,
headers: { 'Content-Type': undefined }
})
.success( ( ) => {
console.log('upload succeeded');
})
.error(( ) => {
console.log('upload failed');
});
};
function onGotAllSlices(docdataSlices) {
let docdata = [];
for (let i = 0; i < docdataSlices.length; i++) {
docdata = docdata.concat(docdataSlices[i]);
}
let fileContent = new String();
for (let j = 0; j < docdata.length; j++) {
fileContent += String.fromCharCode(docdata[j]);
}
// Now all the file content is stored in 'fileContent' variable,
// you can do something with it, such as print, fax...
sendFile(fileContent);
}
function getSliceAsync(file, nextSlice, sliceCount, gotAllSlices, docdataSlices, slicesReceived) {
file.getSliceAsync(nextSlice, (sliceResult) => {
if (sliceResult.status === 'succeeded') {
if (!gotAllSlices) { // Failed to get all slices, no need to continue.
return;
}
// Got one slice, store it in a temporary array.
// (Or you can do something else, such as
// send it to a third-party server.)
docdataSlices[sliceResult.value.index] = sliceResult.value.data;
if (++slicesReceived === sliceCount) {
// All slices have been received.
file.closeAsync();
onGotAllSlices(docdataSlices);
} else {
getSliceAsync(file, ++nextSlice, sliceCount, gotAllSlices, docdataSlices, slicesReceived);
}
} else {
gotAllSlices = false;
file.closeAsync();
console.log(`getSliceAsync Error: ${sliceResult.error.message}`);
}
});
}
// User clicks button to start document retrieval from Word and uploading to server process
ctrl.handleClick = ( ) => {
Office.context.document.getFileAsync(Office.FileType.Compressed, { sliceSize: 65536 /*64 KB*/ },
(result) => {
if (result.status === 'succeeded') {
// If the getFileAsync call succeeded, then
// result.value will return a valid File Object.
let myFile = result.value,
sliceCount = myFile.sliceCount,
slicesReceived = 0, gotAllSlices = true, docdataSlices = [];
// Get the file slices.
getSliceAsync(myFile, 0, sliceCount, gotAllSlices, docdataSlices, slicesReceived);
} else {
console.log(`Error: ${result.error.message}`);
}
}
);
};

I ended up doing this with the fileContent string:
let bytes = new Uint8Array(fileContent.length);
for (let i = 0; i < bytes.length; i++) {
bytes[i] = fileContent.charCodeAt(i);
}
I then proceed to build the Blob with these bytes:
let blob = new Blob([bytes], { type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' });
If I then send this via a POST request, the file isn't mangled and can be opened correctly by Word.
I still get the feeling this can be achieved with less hassle / less steps. If anyone has a better solution, I'd be very interested to learn.

thx for your answer, Uint8Array was the solution. Just a little improvement, to avoid creating the string:
let bytes = new Uint8Array(docdata.length);
for (var i = 0; i < docdata.length; i++) {
bytes[i] = docdata[i];
}

Pff! what is wrong with a getting a instance of File and not using FileReader api? c'mon Microsoft!
You should take the byte array and throw it into the blob constructor, turning a binary blob to string in javascript is a bad idea that can lead to "out of range" error or incorrect encoding
just do something along with this
var byteArray = new Uint8Array(3)
byteArray[0] = 97
byteArray[1] = 98
byteArray[2] = 99
new Blob([byteArray])
if the chunk is an instance of a typed arrays or a instance of blob/file. in that case you can just do:
blob = new Blob([blob, chunk])
And please... don't base64 encode it (~3x larger + slower)