I'm working with an API for uploading a user image, the uploading process is quite simple, just choose the file from the user's device and send it as it is in a FormData (File, Binary).
But, when it comes for downloading this file from the storage, the response is really wired for me and containing some characters that because of it I can't indicate if that is a problem from the back-end handling or it's an invalid file or it's a regular formula that I didn't deal with it before.
my question is what should this data represent? And how to convert it to a file that a user can download?
here is a screenshot of it.
here
After struggling with many cases, the problem was that I didn't define the content-type within the request headers
headers: {
'Content-Type': 'blob'
}
notice that this type of data is a regular Blob file.
for downloading it, review this question JavaScript blob filename
without link
for converting it to a base64 string, review this question Convert blob to base64
Related
I'm looking into an HTTP interface that returns (essentially) a JSON object.
When I access the URL by chrome or firefox, the JSON data is shown with appropriate indents. However, when I download it with curl etc, the data is binary.
I think the browsers know this binary encoding method and show it in a pretty format. (If I save it as a file from the browsers, it is a text file with the indents.)
What do you think this binary encoding is?
(Unfortunately, I can not upload the binary data here...)
[SOLVED]
Browsers send requests with headers but curl doesn't send header by default. That is the reason why I get the different response by these methods. My API returns binarized (compressed) json when called without a header.
You should have a look in the header of the HTTP response message which contains the binary data. There should be values about encoding, content-type and compression.
With this values you can decode the binary data.
I'm creating an API which should return data in a CSV format. I set the content-type header to text/csv but this forces a download of the contents as a csv file.
I'm using NodeJS and the express framework. It could be that this is standard behaviour. However I would like to know how you guys solved this issue.
This is a sample of the code that I'm using:
res.set('Content-Type', 'text/csv');
var toCsv = require('to-csv');
// obj is a just a standard JavaScript object.
res.send(toCsv(obj));
I would like that the person using the API can retrieve data in a CSV format without actually downloading a file
Maybe have a look at this question:
How does browser determine whether to download or show
It's your browser that decides that content of the type "text/csv" should be downloaded.
You should simply consider using another content-type, if you just want the csv to show in the browser as plain text.
Try this instead:
res.set('Content-Type', 'text/plain');
I have an application which uploads a large file in the XML format and sometimes a zip file. Now I want to have that file transferred to other application via REST API. I am thinking to pass the binary data in to json response.
I have the following questions for my approach.
Is sending binary in json the best approach/practice to do it?
Will this be PUT scenario as receiver application doesn't know about new uploaded file?
If that makes it easier for the second service to consume it, I see no problem with it. You can send it on any format you want, as long as it's accepted and you're setting the Content-Type and Accept headers properly.
You use a PUT only when you're sending a complete replacement of the resource at the target URI. If you know the final URI for that and if a GET to the same URI right after the PUT will retrieve as response the same body you just submitted, it makes sense to use PUT, otherwise, use a POST.
I am using the angularJS frontend framework and nodejs/express as a backend server to send and receive JSON. The backend sent a large JSON object to the frontend and I was wondering if I could download the JSON object from the frontend in CSV format.
The data is stored as json in an scope variable: $scope.data in an angular controller. Then I converted the data to a string in CSV format in the variable $scope.CSVdata. How do I get the CSVdata to download from the client browser?
I know nodejs can be set up to send a file in CSV format but it would be nice to keep the backend a clean JSON api.
Referencing this post I've thrown together quick demonstration on how this may be done using AngularJS:
JavaScript Demo (Plunker)
I've wrapped the referenced Base64 code in a service, and use it in the following way:
$scope.downloadCSV = function() {
var data = Base64.encode($scope.CSVData);
window.location.href = "data:text/csv;base64," + data;
};
There are some disadvantages to this method however as mentioned in the comments. I've pulled out some bullet points from the Wikipedia page on this subject. Head over there for the full list.
Data URIs are not separately cached from their containing documents (e.g. CSS or HTML files), therefore the encoded data is downloaded
every time the containing documents are re-downloaded.
Internet Explorer 8 limits data URIs to a maximum length of 32 KB. (Internet Explorer 9 does not have this limitation)
In IE 8 and 9, data URIs can only be used for images, but not for navigation or JavaScript generated file downloads.[7]
Base64-encoded data URIs are 1/3 times larger in size than their binary equivalent. (However, this overhead is reduced to 2–3% if the
HTTP server compresses the response using gzip)
Data URIs do not carry a filename as a normal linked file would. When saving, a default filename for the specified MIME type is
generally used.
[ . . . ]
I am trying to send a generated PDF file (Apache FOP) to the client. I know this can be done by writing the array to the response stream and by setting the correct content type, length and so on in the servlet. My problem is that the whole app was built based on the idea that it will only receive/send JSON. In the servlet's service() method, I have this:
response.setContentType("application/json");
reqBroker.process(request, response);
RequestBroker is the class who processes the JSON (jackson processor), everything is generic and I cannot change it. On top of this, I have to receive the JSON from the request correctly, to access the data and generate my pdf. So those two lines are necessary. But when I send the response, I need to have another content type so that the pdf is displayed correctly in the browser.
So far, I am able to send the byte array as part of the JSON, but then I don't know how to display the array as PDF on the client (if smth like this is even possible).
I would like some suggestions on how can I send my pdf and set the right header, without messing with the JSON. Thanks.
JSON and byte arrays don't mix.
Instead, you should create an <iframe> and point it to a URL that returns a raw PDF.
Take a look here:How to send pdf in json, it lists couple of approaches that you can consider. The easiest way is to convert the binary data into string by using Base64 compression. In C#, this would mean a call to Convert.FromBase64String. However this has space overhead as Base64 compression means around +33% more memory. If you can get away with it, this is the least complicated solution. in case additional size is an issue you can think about zipping it up.