[whatwg] creating a new file via the File API

Bronislav Klučka Bronislav.Klucka at bauglir.com
Sun Dec 18 23:50:47 PST 2011

yes, this is due to default browser behavior (my Chrome is set up to 
always ask).

On 19.12.2011 7:17, David Karger wrote:
> When I run your example in chrome, all those links automatically 
> download the file to the specified filename in my default download 
> directory---none launch the file save dialog.  Of course that's 
> because of how my chrome defaults are set.  And indeed I can right 
> click and file-save-as.  But it's going to be a problem if I want to 
> put a "save as" button on the page---having that result in download to 
> a default directory because that's how chrome defaults are set isn't 
> going to be the right behavior from the user's perspective.   Should 
> there be a way to force open the save dialog, even if the default is 
> to download to a fixed location?
> On 12/19/2011 12:35 AM, Bronislav Klučka wrote:
>> hi,
>> if you look at the generated files examples, what you can see there 
>> (again, only in chrome) is that
>> 1/ I have some data in JS
>> 2/ I create blobbuilder -> blob -> url to that blob
>> 3/ I create a element with URL to that blob and  download attribute
>> 4/ I initiate click on that link programmaticaly
>> the result is is that Save file dialog is opened and when save/ok 
>> button is hit, the blob data is stored in user selected file.
>> Yes, I'm using download attribute, but URL is JS blob (local data).
>> I do not see problem here. What are you missing?
>> And yes, I also do not see security issues here, nothing user cannot 
>> do today with regular download or programmer by uploading data to 
>> server and then download them...
>> B.
>> On 19.12.2011 6:26, David Karger wrote:
>>> Hi,
>>>    What you're doing is certainly connected, but I don't think it 
>>> solves the problem I outlined.  Your approach allows specification 
>>> of the download target as an attribute in html.   That's useful, but 
>>> what's still missing, and I consider important, is a way to connect 
>>> the html document to the "Save As" dialog available on all OSes. 
>>> <input> tags lead browsers to launch the "Open File" dialog, which 
>>> lets the user naturally navigate their file system to select a file 
>>> to open.   Browsers also launch the analogous "Save As" dialog, but 
>>> _only_ when you execute a download from a server.  I think it's 
>>> important to enter the same "Save As" dialog programmatically, for 
>>> client-side generated content.  I don't think this raises the 
>>> security issues discussed at mozilla, because the user is engaged in 
>>> the same interaction as they are on any other file download.
>>> On 12/18/2011 11:13 PM, Bronislav Klučka wrote:
>>>> Hi,
>>>> This is quite crucial functionality and sadly not being addressed 
>>>> as it would seem, because without it application cannot really be 
>>>> applications (all you can do is to prepare data, upload those data 
>>>> to server and let user download it manually by clicking somewhere, 
>>>> which is annoying, unnecessary,  and quite frankly stupid) .
>>>> but there is a way howto allow user to save file from javascript 
>>>> without flash
>>>> http://www.webnt.cz/demos/034_a_download/
>>>> this demo (the generated files) allows you to download/drag'ndrop 
>>>> generated file using JS (no flash)
>>>> it's working in Chrome only at this point
>>>> FF team is having some security issues I've been discussing with them
>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=676619
>>>> B.
>>>> On 16.12.2011 0:58, David Karger wrote:
>>>>> It isn't clear to me that a "tag" question can be addressed by an 
>>>>> "api" answer.   Even if there is an api for saving to file, isn't 
>>>>> there value to being able to declare your intentions through a 
>>>>> tag?  The <input type=file> tag specifies that a user will be able 
>>>>> to interact to specify a file through a dialog.  There's 
>>>>> absolutely no commitment that that file will actually be uploaded 
>>>>> or input.  That's up to the form or the javascript that handles 
>>>>> the input.  It seems entirely consistent to be able to permit 
>>>>> specification of a brand new file in that dialog that <input 
>>>>> type="file"> is already creating.   What some javascript _does_ 
>>>>> with the specified file might need to be implemented using a 
>>>>> filesaver api, but that's separate from the declaration of an 
>>>>> interaction for specifying the file.
>>>>> On 12/15/2011 6:45 PM, whatwg-request at lists.whatwg.org wrote:
>>>>> On Mon, 15 Aug 2011, David Karger wrote:
>>>>>> /
>>>>> />/  Apologies if I'm revisiting old territory.  I've been doing 
>>>>> work on pure
>>>>> />/  html/javascript applications that work entirely clientside
>>>>> />/  (http://projects.csail.mit.edu/exhibit/Dido).  For 
>>>>> persistence, they
>>>>> />/  read and write local files.  There's already an<input 
>>>>> type="file">
>>>>> />/  interface for letting the user specify a file to be read.  
>>>>> And I can use
>>>>> />/  the same interface, inappropriately, to let the user overwrite a
>>>>> />/  preexisting file.  But things get much messier if I want to 
>>>>> let the user
>>>>> />/  specify a _new_ file to be written, because the file-open 
>>>>> dialog doesn't
>>>>> />/  offer users a way to specify a new filename.  What I'd like 
>>>>> to be able
>>>>> />/  to do is specify a tag, or a invoke some javascript method, 
>>>>> that will
>>>>> />/  produce the "save file" dialog typical of most systems, with 
>>>>> a graphical
>>>>> />/  directory browser but including the option to specify a new 
>>>>> filename.
>>>>> />/  This problem isn't unique to me; a discussion on 
>>>>> stackoverflow appears
>>>>> />/  at
>>>>> />/  
>>>>> http://stackoverflow.com/questions/2897619/using-html5-javascript-to-generate-and-save-a-file
>>>>> />/  where the proposed solution is to use flash---and that would 
>>>>> be an
>>>>> />/  unfortunate loss of html5 purity.  They also suggest the hack 
>>>>> of using a
>>>>> />/  data: url but that has size limitations.
>>>>> />/
>>>>> />/  Perhaps<input type="file">  could be given an attribute 
>>>>> specifying
>>>>> />/  whether a new filename is permitted?
>>>>> /
>>>>> On Wed, 7 Sep 2011, Eric U wrote:
>>>>>> /
>>>>> />/  This sounds like a job for the FileSaver interface.  
>>>>> Currently no
>>>>> />/  browser implements it, but we at Chrome have been considering 
>>>>> it.  At
>>>>> />/  TPAC last year we discussed it a bit in the WebApps WG 
>>>>> meeting; IIRC we
>>>>> />/  talked about letting it take a URL instead of or in addition 
>>>>> to just a
>>>>> />/  Blob, for more general utility.
>>>>> />/
>>>>> />/  I suggest you bring it up on public-webapps@, where that spec 
>>>>> lives.
>>>>> />/  
>>>>> http://dev.w3.org/2009/dap/file-system/file-writer.html#idl-def-FileSaver
>>>>> /
>>>>> I agree that an API like FileSaver is the right way to do this. Using
>>>>> <input type=file>  wouldn't really fit well because that's more for
>>>>> providing data for upload than providing a file for writing.


s pozdravem
          Bronislav Klučka

http://www.bauglir.com <http://www.bauglir.com>

Bronislav.Klucka at bauglir.com  <mailto:Bronislav.Klucka at bauglir.com>

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