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Re: Sending email with attachments

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Patricia Shanahan wrote:

> I am writing a data collection application. It needs to run on as many
> tablets and laptops as possible, so I'm writing it in HTML and
> JavaScript. Although I cannot ask end users to buy a particular device,
> I can ask them to install an up to date browser.
> 
> The ultimate destination of the data is a spreadsheet on a workstation
> controlled by the person doing the data entry, or one of their associates.
> 
> The ideal, from my end users' point of view, would be a button they
> could click that would send an e-mail to an address they enter with the
> data attached in .csv format.

You cannot do that client-side, so you will have to do it server-side.  That 
is, have a server-side application compile the .csv and send the e-mail.  
Usually that would be the same server-side application that generated the 
client-side application in the first place.

> I do understand that e-mail would not be the best way of getting the data
> to a web server, but that is not the objective. Forwarding the data from
> my web site to a user-specified e-mail address would require anti-spam
> precautions, and be generally undesirable.

If that is a concern, users of the application need to be authenticated 
before they can use that function (see also [OWASP]).

Only shifting the load from the server to the client is not a solution.  In 
fact, it has the potential to make matters worse.  Client computers 
(including mobile devices) are usually much less protected, thus more easily 
compromised, than servers.
 
> I've done web searches, and the closest I've been able to get is to fold
> the data into a mailto URL as the message body, not an attachment.

Technically, an e-mail attachment is a part of the message body of a multi-
part message, following a delimiter line, own header and usually a Base64-
encoded message-part body (see [RFC2046]); so, in theory, it could work.  
But I would not recommend it for production.  In fact, security measures 
might prevent it.
 
> I would be length limited by the Internet Explorer 2083 char URL limit,
> and I think I would also have to quote URL special characters.

Apparently there are exceptions for certain supported URI schemes, such as 
`data:'. [SO]  There might be one for `mailto:' as well.  However, a 
suitable MUA will need to be installed and configured at the client for this 
to work, which you should not make a requirement.
 
> Another option is to just display the data and invite the user to
> select and copy. The data could then be pasted into the body of an
> e-mail, or into a text file in an editor window. I believe that would
> work, but involves more end user busy work than is ideal.

Yes, in a Web application you should make best use of the *Web* first.
 
> I am very new to JavaScript, so I'm really hoping there is a better way
> of doing this that I have just not found.

Client-side there is nothing better than that, but it does not mean that it 
cannot be done using an ECMAScript implementation server-side.


HTH

PointedEars
___________
[OWASP]
The Open Web Application Security Project: Authentication Cheet Sheet. 
(updated: 2012-09-28) 
<https://www.owasp.org/index.php/Authentication_Cheat_Sheet>

[RFC2046]
Freed, N., Borenstein, N.: Multipurpose Internet Mail Extensions (MIME) Part 
Two: Media Types. November 1996. <http://tools.ietf.org/html/rfc2046>

[SO]
StackOverflow: What is the maximum length of a URL? (updated: 2012-07-12)
<http://stackoverflow.com/a/417184/855543>
-- 
Use any version of Microsoft Frontpage to create your site.
(This won't prevent people from viewing your source, but no one
will want to steal it.)
  -- from <http://www.vortex-webdesign.com/help/hidesource.htm> (404-comp.)

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Thread

Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-01 22:49 -0700
  Re: Sending email with attachments Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-02 04:20 -0700
    Re: Sending email with attachments Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-02 05:16 -0700
      Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-02 07:10 -0700
        Re: Sending email with attachments Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-02 10:57 -0700
    Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-02 07:03 -0700
      Re: Sending email with attachments Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-02 10:50 -0700
        Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-02 11:16 -0700
          Re: Sending email with attachments dann90038@gmail.com - 2012-10-02 12:15 -0700
      Re: Sending email with attachments "Tom de Neef" <tdeneef@qolor.nl> - 2012-10-02 21:28 +0200
        Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-02 12:59 -0700
  Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-02 22:26 +0200
    Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-03 20:04 +0100
    Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-06 02:07 +0100
      Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-06 08:48 +0200
        Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-06 20:29 +0100
          Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-06 21:49 +0200
            Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-07 08:13 +0100
              Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-07 14:28 +0200
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 00:43 +0100
                Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-08 03:26 +0200
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 07:18 +0100
                Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-08 11:13 +0200
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 18:57 +0100
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 09:46 +0100
                Re: Sending email with attachments Erwin Moller <erwinmollerusenet@xs4all.nl> - 2012-10-08 12:01 +0200
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 19:16 +0100
                Re: Sending email with attachments Gene Wirchenko <genew@ocis.net> - 2012-10-08 09:28 -0700
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 18:34 +0100
          Re: Sending email with attachments Stefan Weiss <krewecherl@gmail.com> - 2012-10-07 12:46 +0200
            Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-07 18:55 +0200
              Re: Sending email with attachments Stefan Weiss <krewecherl@gmail.com> - 2012-10-07 20:06 +0200
                Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-07 22:12 +0200
            Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-07 19:54 +0100
            Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 01:09 +0100
              Re: Sending email with attachments Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-08 13:10 +0200
                Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-08 19:20 +0100
              OT: Mac vs PC for development  (Was: Sending email with attachments) Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-10-08 08:38 -0700
  Re: Sending email with attachments Dr J R Stockton <reply1240@merlyn.demon.co.uk.invalid> - 2012-10-03 19:49 +0100
    Re: Sending email with attachments Eli the Bearded <*@eli.users.panix.com> - 2012-10-03 23:08 +0000
      Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-04 02:46 +0100
        Re: Sending email with attachments Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-03 19:42 -0700
    Re: Sending email with attachments Patricia Shanahan <pats@acm.org> - 2012-10-04 02:43 +0100
      Re: Sending email with attachments Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-03 19:54 -0700

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