I need to download a text file hosted on a server.
<html>
<head>
<title>File</title>
</head>
<body>
<a href="http://example.com/test.txt" download>Click here</a>
</body>
</html>
With the above code, instead of downloading the file, I am being redirected to the text file. How do I rectify this?
You can't.
From https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#Attributes
download
This attribute only works for same-origin URLs.
t can only download the same file, give you two solutions
Solution A: You pack your files to. zip/. Rar and other browsers cannot open the file download.
Solution B: forwarded by the back - end, back - end request third-party resources, returned to the front end, front-end using tools such as file-saver save the file.
You CAN, using Javascript
<a onclick="saveFile('url')">Download</a>
<script>
function saveFile(url) {
// Get file name from url.
var filename = url.substring(url.lastIndexOf("/") + 1).split("?")[0];
var xhr = new XMLHttpRequest();
xhr.responseType = 'blob';
xhr.onload = function() {
var a = document.createElement('a');
a.href = window.URL.createObjectURL(xhr.response); // xhr.response is a blob
a.download = filename; // Set the file name.
a.style.display = 'none';
document.body.appendChild(a);
a.click();
delete a;
};
xhr.open('GET', url);
xhr.send();
}
</script>
the saveFile('url') takes string url as an argument so pass in the correct url and your file will download directly. Worked for me
Related
I have a publicly accessible url to a PDF in Google Cloud Storage. I want to be able to create a button/link in react which allows users to download this PDF to their own computer. I'm wondering what is the best approach to do this and which libraries would be of help? Is there any documentation on this? Thanks
In order to force download a file, you have a number of options. First, the easiest is using the download attribute of an anchor tag:
PDF
However, this is not supported on IE and a number of other browsers in their earlier versions. But the maximum impact of this is it will open in a new tab which in my opinion is graceful degradation. See the full list of supported versions.
If this is not enough, you have to make some changes server-side. You can configure a server in many ways, but as an example, a .htaccess file can have the following:
<Files *.pdf>
Header set Content-Disposition attachment
</Files>
You can dynamically generate a link or button. Snippet bellow:
var sampleBytes = new Int8Array(4096); // In your case it should be your file
var saveByteArray = (function () {
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
return function (data, name) {
var blob = new Blob(data, {type: "octet/stream"}), // or application/pdf
url = window.URL.createObjectURL(blob);
a.href = url;
a.download = name;
a.click();
window.URL.revokeObjectURL(url);
};
}());
saveByteArray([sampleBytes], 'example.txt'); // You can define the filename
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.
I tried to download a zipfile from a webserver programatically using javascript- and am facing challenges with the archive getting corrupted.
I am using the following function to download
function download(){
var http = new XMLHttpRequest();
http.open("GET", 'http://jadonchemicals.com/sample.zip');
http.setRequestHeader("dataType", "jsonp");
http.onreadystatechange = function () {
if (http.readyState == 4 && http.status == 200)
{
var blobdata=new Blob([http.responseText], {type: "application/zip"});
var a = document.createElement("a");
a.href = window.URL.createObjectURL(blobdata);
a.click();
}
};
http.send();
}
I get the following errors when I try to open the archive
a) The file header is corrupt
b) unexpected end of archive
As an example, while downloading the sample.zip file on this link, the file does get downloaded to a size of 975k.
http://jadonchemicals.com/Blobtozip/
When I try to do the same programatically using javascript by linking the script to a button, the file size increases to 1779k and the file is corrupted
I suspect this is a result of an encoding issue. Could you suggest what I should do to resolve?
You can download a file in javascript like this:
<iframe id="my_iframe" style="display:none;"></iframe>
<script>
function Download(url) {
document.getElementById('my_iframe').src = url;
};
Download("http://jadonchemicals.com/sample.zip")
</script>
You just need to insert the code into your html document.
I have tried downloading your specified file using this and it was the correct 975KB and was not corrupt.
I am doing a chrome extension capable of getting from a webpage an image, and after I got it, I'm trying to upload it to an intranet server automatically without user iteration.
I am doing this right now.
This is on Content_script.js
...
x = $(frame1).contents().find("#image");
chrome.extension.sendRequest(x[0].src);
...
This is on background.js
chrome.extension.onRequest.addListener(function(links) {
chrome.downloads.download( { url: links ,
conflictAction: "overwrite",
filename: "get_image.jpg" },
function(DescargaId) {
var formData = new FormData();
formData.append("doc", Blob, "~/Downloads/get_image.jpg");
var request = new XMLHttpRequest();
request.open("POST", "http://192.168.0.30/app_get_pictures/upload_img.php");
request.setRequestHeader("Content-Type", "multipart/form-data");
request.send(formData);
} );
This on upload_img.php
...
$uploaddir = $_SERVER['DOCUMENT_ROOT'].'/app_get_pictures/images/';
$uploadfile = $uploaddir . basename($_FILES['doc']['name']);
move_uploaded_file($_FILES['doc']['tmp_name'], $uploadfile);
...
With this, I already download the image successfully to the local machine, but can't upload the image to the server.
It is possible to do this, or even if I can upload the image to the server directly without download it first to the local machine.
Note: I don't have any tag form on a popup page in the extension solution, and I don't have a popup page neither, because as I already said, I don't need any iteration from the user.
Thanks for your help!
Thanks to https://stackoverflow.com/users/934239/xan I resolved this problem using his advise, here is the resulting working code.
...
// With this I can download or get content image into var blob
var xhr = new XMLHttpRequest();
var kima = $(frame1).contents().find("#image");
xhr.open('GET',kima[0].src,true);
xhr.responseType = 'blob';
xhr.onload = function(e) {
if (this.status == 200) {
var blob = new Blob([this.response], {type: 'image/png'});
send_image(blob);
}
};
xhr.send();
....
// After the image is loaded into var blob, it can be send
// to the server side
function send_image(x){
var formData = new FormData();
formData.append("doc", x);
var request = new XMLHttpRequest();
request.open("POST", "http://192.168.0.30/app_get_image/upload_img.php");
request.send(formData);
}
All this code into the content_script of the chrome extension. Also the code of the background using API download isn't needed anymore.
Hope this could works for anybody else.
Thanks again.
Besides the fact that the callback of downloads.download does NOT indicate that the file is already downloaded (only that the download is queued)..
formData.append("doc", Blob, "~/Downloads/get_image.jpg");
What do you think this code does? Documentation, for reference.
The second parameter is supposed to hold the data of the file; the third parameter is just the file name for the purposes of naming anonymous data (e.g. in a Blob)
Instead, you pass the Blob object itself; not an instance of Blob with the data.
In fact, with this architecture, you won't be able to upload the file, since at no point does chrome.downloads API give you access to the file's contents, and you can't just access a file on a disk by filename (which is what I think you thought this code would do).
To actually access the data, you need to request it yourself with XHR (or Fetch API if you want to be "modern"). Then, you get the response object which you can request to be a Blob. Then, you can both upload the blob and invoke chrome.downloads together with createObjectURL to "download" it from your extension's memory.
I'm building chrome extension for watching videos.
I have problem with adding subtitles and captions to video. I have subtitle as string (from ajax call), and problem is that <track> tag in html5 requires a file, (url to file).
Is there a good way to create a file from string in chrome exstension / javascript, and than accessing it via url/path?
Thx
Creating an URL from a string is very easy with the Blob constructor and URL.createObjectURL:
var content = 'some string';
var url = URL.createObjectURL(new Blob([content], { type: 'text/plain' }));
If you're using AJAX, then you don't need to do a string-to-blob conversion. Just set responseType = 'blob'; directly:
var x = new XMLHttpRequest();
x.open('GET', 'http://example.com/');
x.responseType = 'blob';
x.onload = function() {
var url = URL.createObjectURL(x.response);
// ...
};
x.send();
Instead of creating a file, you can try generating a data URI:
src = 'data:text/plain,' + encodeURIComponent(subtitleString);
or:
src = 'data:text/plain;base64,' + btoa(subtitleString);
You'll need to add encoding info if you are dealing with non US-ASCII subtitles.