Corrupt Word Document on Second Download - javascript

I have a question for a confidential project that I am working on, so I cannot share too much detail. Hopefully the below code is enough to at least provide some suggestions as to what can be wrong.
Whenever I programmatically download a word blob from an anchor link, it fails on the second try only saying that it could not open the file as it is corrupt. I also see that the file is about 14KB larger.
// route file
var buffer = await Packer.toBuffer(doc); // create buffer using DOCX.js Packer
res.header(
"output_name",
`${unique_output_str}.docx` // <--- this is a template string which changes each time the document is generated, based on unique attributes that the user selects
);
res.send(Buffer.from(buffer));
How I download:
var response = await axios.patch(
path, // <--- this is defined elsewhere (not relevant to question)
formData, // <--- this is defined elsewhere (not relevant to question)
{ responseType: "blob" }
);
const url = URL.createObjectURL(
new Blob([response.data], {
type:
"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
})
);
const link = document.createElement("a");
link.href = url;
link.download = response.headers["output_name"];
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
How come my first download after form submission produces a good docx file, but resubmitting the form with other data (changes in text for text input) produces corrupt files?

Related

Onclick save drawing for Javascript in <script> element [duplicate]

I'm playing with the idea of making a completely JavaScript-based zip/unzip utility that anyone can access from a browser. They can just drag their zip directly into the browser and it'll let them download all the files within. They can also create new zip files by dragging individual files in.
I know it'd be better to do it serverside, but this project is just for a bit of fun.
Dragging files into the browser should be easy enough if I take advantage of the various methods available. (Gmail style)
Encoding/decoding should hopefully be fine. I've seen some as3 zip libraries so I'm sure I should be fine with that.
My issue is downloading the files at the end.
window.location = 'data:jpg/image;base64,/9j/4AAQSkZJR....'
this works fine in Firefox but not in Chrome.
I can embed the files as images just fine in chrome using <img src="data:jpg/image;ba.." />, but the files won't necessarily be images. They could be any format.
Can anyone think of another solution or some kind of workaround?
If you also want to give a suggested name to the file (instead of the default 'download') you can use the following in Chrome, Firefox and some IE versions:
function downloadURI(uri, name) {
var link = document.createElement("a");
link.download = name;
link.href = uri;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
delete link;
}
And the following example shows it's use:
downloadURI("data:text/html,HelloWorld!", "helloWorld.txt");
function download(dataurl, filename) {
const link = document.createElement("a");
link.href = dataurl;
link.download = filename;
link.click();
}
download("data:text/html,HelloWorld!", "helloWorld.txt");
or:
function download(url, filename) {
fetch(url)
.then(response => response.blob())
.then(blob => {
const link = document.createElement("a");
link.href = URL.createObjectURL(blob);
link.download = filename;
link.click();
})
.catch(console.error);
}
download("https://get.geojs.io/v1/ip/geo.json","geoip.json")
download("data:text/html,HelloWorld!", "helloWorld.txt");
Ideas:
Try a <a href="data:...." target="_blank"> (Untested)
Use downloadify instead of data URLs (would work for IE as well)
Want to share my experience and help someone stuck on the downloads not working in Firefox and updated answer to 2014.
The below snippet will work in both firefox and chrome and it will accept a filename:
// Construct the <a> element
var link = document.createElement("a");
link.download = thefilename;
// Construct the uri
var uri = 'data:text/csv;charset=utf-8;base64,' + someb64data
link.href = uri;
document.body.appendChild(link);
link.click();
// Cleanup the DOM
document.body.removeChild(link);
Here is a pure JavaScript solution I tested working in Firefox and Chrome but not in Internet Explorer:
function downloadDataUrlFromJavascript(filename, dataUrl) {
// Construct the 'a' element
var link = document.createElement("a");
link.download = filename;
link.target = "_blank";
// Construct the URI
link.href = dataUrl;
document.body.appendChild(link);
link.click();
// Cleanup the DOM
document.body.removeChild(link);
delete link;
}
Cross-browser solutions found up until now:
downloadify -> Requires Flash
databounce -> Tested in IE 10 and 11, and doesn't work for me. Requires a servlet and some customization. (Incorrectly detects navigator. I had to set IE in compatibility mode to test, default charset in servlet, JavaScript options object with correct servlet path for absolute paths...) For non-IE browsers, it opens the file in the same window.
download.js -> http://danml.com/download.html Another library similar but not tested. Claims to be pure JavaScript, not requiring servlet nor Flash, but doesn't work on IE <= 9.
There are several solutions but they depend on HTML5 and haven't been implemented completely in some browsers yet. Examples below were tested in Chrome and Firefox (partly works).
Canvas example with save to file support. Just set your document.location.href to the data URI.
Anchor download example. It uses <a href="your-data-uri" download="filename.txt"> to specify file name.
Combining answers from #owencm and #Chazt3n, this function will allow download of text from IE11, Firefox, and Chrome. (Sorry, I don't have access to Safari or Opera, but please add a comment if you try and it works.)
initiate_user_download = function(file_name, mime_type, text) {
// Anything but IE works here
if (undefined === window.navigator.msSaveOrOpenBlob) {
var e = document.createElement('a');
var href = 'data:' + mime_type + ';charset=utf-8,' + encodeURIComponent(text);
e.setAttribute('href', href);
e.setAttribute('download', file_name);
document.body.appendChild(e);
e.click();
document.body.removeChild(e);
}
// IE-specific code
else {
var charCodeArr = new Array(text.length);
for (var i = 0; i < text.length; ++i) {
var charCode = text.charCodeAt(i);
charCodeArr[i] = charCode;
}
var blob = new Blob([new Uint8Array(charCodeArr)], {type: mime_type});
window.navigator.msSaveOrOpenBlob(blob, file_name);
}
}
// Example:
initiate_user_download('data.csv', 'text/csv', 'Sample,Data,Here\n1,2,3\n');
This can be solved 100% entirely with HTML alone. Just set the href attribute to "data:(mimetypeheader),(url)". For instance...
<a
href="data:video/mp4,http://www.example.com/video.mp4"
target="_blank"
download="video.mp4"
>Download Video</a>
Working example: JSFiddle Demo.
Because we use a Data URL, we are allowed to set the mimetype which indicates the type of data to download. Documentation:
Data URLs are composed of four parts: a prefix (data:), a MIME type indicating the type of data, an optional base64 token if non-textual, and the data itself. (Source: MDN Web Docs: Data URLs.)
Components:
<a ...> : The link tag.
href="data:video/mp4,http://www.example.com/video.mp4" : Here we are setting the link to the a data: with a header preconfigured to video/mp4. This is followed by the header mimetype. I.E., for a .txt file, it would would be text/plain. And then a comma separates it from the link we want to download.
target="_blank" : This indicates a new tab should be opened, it's not essential, but it helps guide the browser to the desired behavior.
download: This is the name of the file you're downloading.
If you only need to actually have a download action, like if you bind it to some button that will generate the URL on the fly when clicked (in Vue or React for example), you can do something as easy as this:
const link = document.createElement('a')
link.href = url
link.click()
In my case, the file is already properly named but you can set it thanks to filename if needed.
For anyone having issues in IE:
dataURItoBlob = function(dataURI) {
var binary = atob(dataURI.split(',')[1]);
var array = [];
for(var i = 0; i < binary.length; i++) {
array.push(binary.charCodeAt(i));
}
return new Blob([new Uint8Array(array)], {type: 'image/png'});
}
var blob = dataURItoBlob(uri);
window.navigator.msSaveOrOpenBlob(blob, "my-image.png");
This code was originally provided by #Yetti on this answer (separate question).
Your problem essentially boils down to "not all browsers will support this".
You could try a workaround and serve the unzipped files from a Flash object, but then you'd lose the JS-only purity (anyway, I'm not sure whether you currently can "drag files into browser" without some sort of Flash workaround - is that a HTML5 feature maybe?)
Coming late to the party, if you'd like to use a function without using the DOM, here it goes, since the DOM might not even be available for whatever reason.
It should be applicable in any Browser which has the fetch API.
Just test it here:
// declare the function
function downloadAsDataURL (url) {
return new Promise((resolve, reject) => {
fetch(url)
.then(res => res.blob())
.then(blob => {
const reader = new FileReader()
reader.readAsDataURL(blob)
reader.onloadend = () => resolve(reader.result)
reader.onerror = err => reject(err)
})
.catch(err => reject(err))
})
}
// simply use it like this
downloadAsDataURL ('https://cdn-icons-png.flaticon.com/512/3404/3404134.png')
.then((res) => {
console.log(res)
})
.catch((err) => {
console.error(err)
})
export const downloadAs = async (url: string, name: string) => {
const blob = await axios.get(url, {
headers: {
'Content-Type': 'application/octet-stream',
},
responseType: 'blob',
});
const a = document.createElement('a');
const href = window.URL.createObjectURL(blob.data);
a.href = href;
a.download = name;
a.click();
};
You can use a clean code solution, inform your url in a constant, and set it as param of open method instead in object window.
const url = "file url here"
window.open(url)

Using blob to make .docx file from md input?

I am trying to create a custom Word document output using Hogan and Blob. It works as expected for .md files but I am trying to generalize to .docx or other file types.
From following an online tutorial this is what I have so far:
app.markdown = app.template.render(data);
updateLink(
app.markdown,
"text/plain",
"example.md",
document.getElementById("mdLink")
);
app.markdown is valid markdown as expected. And this is the updateLink function:
function updateLink(content, contentType, filename, link) {
const blob = new Blob([content], { type: contentType });
const url = window.URL.createObjectURL(blob);
window.URL.revokeObjectURL(link.href);
link.href = url;
link.download = filename;
}
So, the above works for .md files, but when I try changing "example.md" to "example.docx" and "text/plain" to "application/msword", and clicking the link results in a .docx file being downloaded but Word is not able to open the content. So what format do I need to convert my markdown to so that it works natively with Word? (Ideally I would also be able to preserve some of the markdown styling into the Word styling). Thanks!

send file from server to client on bokeh

I have made a user interface to fetch data from a MySQL table and visualize it. It is running on a bokeh server. My users connect remotely to the server using their browser (firefox). This works perfectly fine: I simply import the table into a pandas dataframe.
My users also need to download the table as excel. This means I cannot use the export_csv example which is pure javascript.
I have no experience with JavaScript. All I want is to transfer a file from the directory where my main.py is to the client side.
The technique I have tried so far is to join a normal on_click callback to a button, export the information I need to 'output.xls', then change a parameter from a dummy glyph which in turn runs a Javascript code. I got the idea from Bokeh widgets call CustomJS and Python callback for single event? . Note I haven't set the alpha to 0, so that I can see if the circle is really growing upon clicking the download button.
At the bottom of my message you can find my code. You can see I have tried with both XMLHttpRequest and with Fetch directly. In the former case, nothing happens. In the latter case I obtain a file named "mydata.xlsx" as expected, however it contains only this raw text: <html><title>404: Not Found</title><body>404: Not Found</body></html>.
Code:
p = figure(title='mydata')
#download button
download_b = Button(label="Download", button_type="success")
download_b.on_click(download)
#dummy idea from https://stackoverflow.com/questions/44212250/bokeh-widgets-call-customjs-and-python-callback-for-single-event
dummy = p.circle([1], [1],name='dummy')
JScode_xhr = """
var filename = p.title.text;
filename = filename.concat('.xlsx');
alert(filename);
var xhr = new XMLHttpRequest();
xhr.open('GET', '/output.xlsx', true);
xhr.responseType = 'blob';
xhr.onload = function(e) {
if (this.status == 200) {
var blob = this.response;
alert('seems to work...');
if (navigator.msSaveBlob) {
navigator.msSaveBlob(blob, filename);
}
else {
var link = document.createElement("a");
link = document.createElement('a');
link.href = URL.createObjectURL(blob);
window.open(link.href, '_blank');
link.download = filename;
link.target = "_blank";
link.style.visibility = 'hidden';
link.dispatchEvent(new MouseEvent('click'));
URL.revokeObjectURL(url);
}
}
else {
alert('Ain't working!');
}
};
"""
JScode_fetch = """
var filename = p.title.text;
filename = filename.concat('.xlsx');
alert(filename);
fetch('/output.xlsx').then(response => response.blob())
.then(blob => {
alert(filename);
//addresses IE
if (navigator.msSaveBlob) {
navigator.msSaveBlob(blob, filename);
}
else {
var link = document.createElement("a");
link = document.createElement('a')
link.href = URL.createObjectURL(blob);
window.open(link.href, '_blank');
link.download = filename
link.target = "_blank";
link.style.visibility = 'hidden';
link.dispatchEvent(new MouseEvent('click'))
URL.revokeObjectURL(url);
}
return response.text();
});
"""
dummy.glyph.js_on_change('size', CustomJS(args=dict(p=p),
code=JScode_fetch))
plot_tab = Panel(child=row(download_b,p),
title="Plot",
closable=True,
name=str(self.test))
def download():
writer = pd.ExcelWriter('output.xlsx')
data.to_excel(writer,'data')
infos.to_excel(writer,'info')
dummy = p.select(name='dummy')[0]
dummy.glyph.size = dummy.glyph.size +1
Trying out Eugene Pakhomov's answer, I found what was the issue.
The javascript code I named JScode_fetch is almost correct, however I get a 404 because it is not pointing correctly to the right path.
I made my application in the directory format: I changed my .py file to main.py, placed it into a folder called app, and changed this one line of code in JScode_fetch:
fetch('/app/static/output.xlsx', {cache: "no-store"}).then(response => response.blob())
[...]
You can see the problem was that it was trying to access localhost:5006/output.xlsx, instead of localhost:5006/app/output.xlsx. As it is in directory format, the right link is now localhost:5006/app/static/output.xlsx to count for the static directory.
I also changed a few lines in the download function:
def download():
dirpath = os.path.join(os.path.dirname(__file__),'static')
writer = pd.ExcelWriter(os.path.join(dirpath,'output.xlsx'))
writer = pd.ExcelWriter('output.xlsx')
data.to_excel(writer,'data')
infos.to_excel(writer,'info')
dummy = p.select(name='dummy')[0]
dummy.glyph.size = dummy.glyph.size +1
Now it is working flawlessly!
edit: I have added , {cache: "no-store"} within the fetch() function. Otherwise the browser thinks the file is the same if you have to download a different dataframe excel while using the same output.xlsx filename. More info here.
bokeh serve creates just a few predefined handlers to serve some static files and a WebSocket connection - by default, it doesn't have anything to serve files from the root of the project.
Instead of using the one-file format, you can try using the directory format, save your files to static directory and download them from /static/.
One downside of this approach is that you still have to write that convoluted code to just make your backend create the file before a user downloads it.
The best solution would be to go one step further and embed Bokeh Server as a library into your main application. Since you don't have any non-Bokeh code, the simplest way would be to go with Tornado (an example).
bokeh.server.server.Server accepts extra_patterns argument - you can add a handler there to dynamically create Excel files and serve them from, say, /data/. After all that, the only thing that you need in your front-end is a single link to the Excel file.

How can I use download a .zip file from a URL to the user in Angular 4?

I have about 10 .csv and 10 .xlsx files of sale items that are each zipped and and deployed daily at a URL specified by an API get request I make depending on which file the user wants to download.
So basically, when I call the API, I get back a string of the destination URL, and it's hot, so if you navigate to that url, the file downloads for the user, however this is how I'm doing it, and I'm wondering if there is a better way, or an Angular way?
Here is the response I get the URL from the API get request when the user changes a radio button for the file they want:
{
"fileUrl": "https://example.com.csv.zip"
}
Then I'm using #ngrx store to set that destination URL in state. I won't go into that here...
Here is the method that is called when the user clicks the download button:
downloadCSV() {
const url = this.state.destinationUrl;
this.http.get(url).subscribe(res => {
// Don't like modifying the DOM just to download a file :(
const link = document.createElement('a');
link.download = this.state.destinationUrl;
link.href = this.state.destinationUrl;
document.body.appendChild(link);
// Don't like forcing an event :(
link.click();
}, (error) => {
console.log('error fetching file download');
});
}
The problem is, this seems hacky, and I am looking for a better solution. Is there a better way of doing this, keeping in ind that I want to avoid popup blockers? I have seen file-saver used in Angular but I don't think I can create a Blob out of the .zip file location and us FileSaver.saveAs(blob, 'example.zip'). Any suggestions would be greatly appreciated.
download() {
const url = 'mydomain.com';
if (url) {
const link = document.createElement('a');
link.href = url;
document.body.appendChild(link);
link.click();
}
}

Download data URL file

I'm playing with the idea of making a completely JavaScript-based zip/unzip utility that anyone can access from a browser. They can just drag their zip directly into the browser and it'll let them download all the files within. They can also create new zip files by dragging individual files in.
I know it'd be better to do it serverside, but this project is just for a bit of fun.
Dragging files into the browser should be easy enough if I take advantage of the various methods available. (Gmail style)
Encoding/decoding should hopefully be fine. I've seen some as3 zip libraries so I'm sure I should be fine with that.
My issue is downloading the files at the end.
window.location = 'data:jpg/image;base64,/9j/4AAQSkZJR....'
this works fine in Firefox but not in Chrome.
I can embed the files as images just fine in chrome using <img src="data:jpg/image;ba.." />, but the files won't necessarily be images. They could be any format.
Can anyone think of another solution or some kind of workaround?
If you also want to give a suggested name to the file (instead of the default 'download') you can use the following in Chrome, Firefox and some IE versions:
function downloadURI(uri, name) {
var link = document.createElement("a");
link.download = name;
link.href = uri;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
delete link;
}
And the following example shows it's use:
downloadURI("data:text/html,HelloWorld!", "helloWorld.txt");
function download(dataurl, filename) {
const link = document.createElement("a");
link.href = dataurl;
link.download = filename;
link.click();
}
download("data:text/html,HelloWorld!", "helloWorld.txt");
or:
function download(url, filename) {
fetch(url)
.then(response => response.blob())
.then(blob => {
const link = document.createElement("a");
link.href = URL.createObjectURL(blob);
link.download = filename;
link.click();
})
.catch(console.error);
}
download("https://get.geojs.io/v1/ip/geo.json","geoip.json")
download("data:text/html,HelloWorld!", "helloWorld.txt");
Ideas:
Try a <a href="data:...." target="_blank"> (Untested)
Use downloadify instead of data URLs (would work for IE as well)
Want to share my experience and help someone stuck on the downloads not working in Firefox and updated answer to 2014.
The below snippet will work in both firefox and chrome and it will accept a filename:
// Construct the <a> element
var link = document.createElement("a");
link.download = thefilename;
// Construct the uri
var uri = 'data:text/csv;charset=utf-8;base64,' + someb64data
link.href = uri;
document.body.appendChild(link);
link.click();
// Cleanup the DOM
document.body.removeChild(link);
Here is a pure JavaScript solution I tested working in Firefox and Chrome but not in Internet Explorer:
function downloadDataUrlFromJavascript(filename, dataUrl) {
// Construct the 'a' element
var link = document.createElement("a");
link.download = filename;
link.target = "_blank";
// Construct the URI
link.href = dataUrl;
document.body.appendChild(link);
link.click();
// Cleanup the DOM
document.body.removeChild(link);
delete link;
}
Cross-browser solutions found up until now:
downloadify -> Requires Flash
databounce -> Tested in IE 10 and 11, and doesn't work for me. Requires a servlet and some customization. (Incorrectly detects navigator. I had to set IE in compatibility mode to test, default charset in servlet, JavaScript options object with correct servlet path for absolute paths...) For non-IE browsers, it opens the file in the same window.
download.js -> http://danml.com/download.html Another library similar but not tested. Claims to be pure JavaScript, not requiring servlet nor Flash, but doesn't work on IE <= 9.
There are several solutions but they depend on HTML5 and haven't been implemented completely in some browsers yet. Examples below were tested in Chrome and Firefox (partly works).
Canvas example with save to file support. Just set your document.location.href to the data URI.
Anchor download example. It uses <a href="your-data-uri" download="filename.txt"> to specify file name.
Combining answers from #owencm and #Chazt3n, this function will allow download of text from IE11, Firefox, and Chrome. (Sorry, I don't have access to Safari or Opera, but please add a comment if you try and it works.)
initiate_user_download = function(file_name, mime_type, text) {
// Anything but IE works here
if (undefined === window.navigator.msSaveOrOpenBlob) {
var e = document.createElement('a');
var href = 'data:' + mime_type + ';charset=utf-8,' + encodeURIComponent(text);
e.setAttribute('href', href);
e.setAttribute('download', file_name);
document.body.appendChild(e);
e.click();
document.body.removeChild(e);
}
// IE-specific code
else {
var charCodeArr = new Array(text.length);
for (var i = 0; i < text.length; ++i) {
var charCode = text.charCodeAt(i);
charCodeArr[i] = charCode;
}
var blob = new Blob([new Uint8Array(charCodeArr)], {type: mime_type});
window.navigator.msSaveOrOpenBlob(blob, file_name);
}
}
// Example:
initiate_user_download('data.csv', 'text/csv', 'Sample,Data,Here\n1,2,3\n');
This can be solved 100% entirely with HTML alone. Just set the href attribute to "data:(mimetypeheader),(url)". For instance...
<a
href="data:video/mp4,http://www.example.com/video.mp4"
target="_blank"
download="video.mp4"
>Download Video</a>
Working example: JSFiddle Demo.
Because we use a Data URL, we are allowed to set the mimetype which indicates the type of data to download. Documentation:
Data URLs are composed of four parts: a prefix (data:), a MIME type indicating the type of data, an optional base64 token if non-textual, and the data itself. (Source: MDN Web Docs: Data URLs.)
Components:
<a ...> : The link tag.
href="data:video/mp4,http://www.example.com/video.mp4" : Here we are setting the link to the a data: with a header preconfigured to video/mp4. This is followed by the header mimetype. I.E., for a .txt file, it would would be text/plain. And then a comma separates it from the link we want to download.
target="_blank" : This indicates a new tab should be opened, it's not essential, but it helps guide the browser to the desired behavior.
download: This is the name of the file you're downloading.
If you only need to actually have a download action, like if you bind it to some button that will generate the URL on the fly when clicked (in Vue or React for example), you can do something as easy as this:
const link = document.createElement('a')
link.href = url
link.click()
In my case, the file is already properly named but you can set it thanks to filename if needed.
For anyone having issues in IE:
dataURItoBlob = function(dataURI) {
var binary = atob(dataURI.split(',')[1]);
var array = [];
for(var i = 0; i < binary.length; i++) {
array.push(binary.charCodeAt(i));
}
return new Blob([new Uint8Array(array)], {type: 'image/png'});
}
var blob = dataURItoBlob(uri);
window.navigator.msSaveOrOpenBlob(blob, "my-image.png");
This code was originally provided by #Yetti on this answer (separate question).
Your problem essentially boils down to "not all browsers will support this".
You could try a workaround and serve the unzipped files from a Flash object, but then you'd lose the JS-only purity (anyway, I'm not sure whether you currently can "drag files into browser" without some sort of Flash workaround - is that a HTML5 feature maybe?)
Coming late to the party, if you'd like to use a function without using the DOM, here it goes, since the DOM might not even be available for whatever reason.
It should be applicable in any Browser which has the fetch API.
Just test it here:
// declare the function
function downloadAsDataURL (url) {
return new Promise((resolve, reject) => {
fetch(url)
.then(res => res.blob())
.then(blob => {
const reader = new FileReader()
reader.readAsDataURL(blob)
reader.onloadend = () => resolve(reader.result)
reader.onerror = err => reject(err)
})
.catch(err => reject(err))
})
}
// simply use it like this
downloadAsDataURL ('https://cdn-icons-png.flaticon.com/512/3404/3404134.png')
.then((res) => {
console.log(res)
})
.catch((err) => {
console.error(err)
})
export const downloadAs = async (url: string, name: string) => {
const blob = await axios.get(url, {
headers: {
'Content-Type': 'application/octet-stream',
},
responseType: 'blob',
});
const a = document.createElement('a');
const href = window.URL.createObjectURL(blob.data);
a.href = href;
a.download = name;
a.click();
};
You can use a clean code solution, inform your url in a constant, and set it as param of open method instead in object window.
const url = "file url here"
window.open(url)

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