File Submissions

This example shows a Python CGI script and HTML page to allow people to submit files.

Each submission is assigned its own sub-directory, with two files in it. The file submission will contain the file that was submitted. The file info will have the other information that the user provided.

`FieldStorage` class

The preferred way to obtain form variables or the sections of a multipart file object is to use an instance of the FieldStorage class:

   form = cgi.FieldStorage()

The top-level FieldStorage object will have an attribute, list, that contains a list fo all the fields contained in the query. Each of these will be a FieldStorage object.

You can ask if a name, key is assigned one or more values in the query by calling
```
   form.has_key[key]
```
You can get a list of all the names assigned values in the form by calling
```
   form.keys()
```
You can subscript with the name, key, and get a FieldStorage object associated with the key:
```
   form[key]
```

`FieldStorage` objects

FieldStorage objects have these attributes:

name - The name of the field, or equivalently the name of the query variable.
value - The value of the field. For everything except a file input, this is what you want.
filename - If the field corresponds to a file input, filename is the name of the file on the browser's machine. See line 63 of the Python program below:
file - If the field corresponds to a file input, the file attribute is an open file object that can be used for reading the file. See lines 40-44 of the Python script below

Reference

George K. Thiruvathukal, Thomas W. Christopher, and John P. Shafaee, Web Programming, Techniques for Integrating Python, Linux, Apache, and MySQL, Prentice-Hall, 2002. p 348-354.

This book discusses some interesting Python software, but apparently the code is not available anymore, at least not from www.tools-of-computing.com, as stated in the book.

`submitfile.py`

01: #!/usr/bin/python
02: import cgi, cgitb, os, sys
03: import types, time, shutil
04: cgitb.enable(); # formats errors in HTML
05: 
06: sys.stderr = sys.stdout
07: print "Content-type: text/html"
08: print
09: print '''<html>
10: <head>
11: <title>File upload</title>
12: </head>
13: <body>'''
14: 
15: form = cgi.FieldStorage()
16: 
17: okay = 1
18: if not form.getvalue('LASTNAME'):
19:     if okay: '<h1>Problem</h1>'
20:     print '<p>Your last name is required.</p>'
21:     okay = 0
22: if not form.getvalue('EMAIL'):
23:     if okay: '<h1>Problem</h1>'
24:     print '<p>Your email address is required.</p>'
25:     okay = 0
26: if not form.getvalue('FILE'):
27:     if okay: '<h1>Problem</h1>'
28:     print '<p>A file is required.</p>'
29:     okay = 0
30: if not okay:
31:     print '<p>Please try again.</p>'
32:     print '</body></html>'
33:     sys.exit()
34: 
35: docId = 'ID' + hex(os.getpid())[2:]+'-'
36: docId = docId + hex(long(time.time()))[2:-1]
37: dir = docId
38: os.mkdir(dir)
39: os.chmod(dir,0775)
40: file = form["FILE"].file
41: dst = dir + '/submission'
42: dstfile=open(dst,'wb')
43: shutil.copyfileobj(file,dstfile,1024)
44: dstfile.close()
45: filesize = os.path.getsize(dst)
46: if filesize==0:
47:     print '<h1>Problem</h1>'
48:     print '<p>The file did not come through.'
49:     print 'Make sure it exists and is not a directory and try again.</p>'
50:     print '<p>Please try again</p>'
51:     os.remove(dst)
52:     os.rmdir(dir)
53:     print '</body></html>'
54:     sys.exit()
55:     
56: os.chmod(dst,0664)
57: info=open(dir+'/info','w')
58: info.write('Last: '+form['LASTNAME'].value + os.linesep)
59: first = form.getvalue('FIRSTNAME')
60: if first:
61:     info.write('First: '+ first + os.linesep)
62: info.write('Email: ' + form['EMAIL'].value+os.linesep)
63: info.write('Filename: ' + form['FILE'].filename+os.linesep)
64: info.write(os.linesep + form['COVER'].value+os.linesep)
65: info.close()
66: os.chmod(dir+'/info',0664)
67: print '<h1>Thank you for your submission</h1>'
68: print '<p>Your submission ID is: <b>', docId + '</b>.'
69: print '<p>Please refer to it in all communications.'
70: print '<p>You submitted file <b>', form['FILE'].filename + ' </b>'
71: print '<p>Filesize: <b>', filesize, 'bytes</b>'
72: print '</body></html>'

submitfile.html

`submitfile.html`

01: <html>
02: <head><title>Submit a file</title></head>
03: <body>
04: <h1>Submit a file</h1>
05: <form action="https://johnloomis.org/python/submitfile.py"
06: enctype="multipart/form-data" method="POST">
07: <h2>Your name and email</h2>
08: 
09: <p><table>
10: <tr><td>Last name: <td> <input type="text" name="LASTNAME" size=30>
11: <tr><td>First name: <td> <input type="text" name="FIRSTNAME" size=30>
12: <tr><td>Email: <td> <input type="text" name="EMAIL" size=50>
13: </table>
14: 
15: <h2>Document</h2>
16: 
17: <p>The file: <input type="FILE" name="FILE" size=20>&nbsp;&nbsp;
18: 
19: <h2>Cover note</h2>
20: 
21: <p><textarea name="COVER" cols=40 rows=8 wrap="physical"></textarea>
22: 
23: <p><input type="SUBMIT">
24: </form>
25: </body><html>

Results

Here is a sample response for a successful transmission:

Thank you for your submission

Your submission ID is: ID111c-47E6AC49.
Please refer to it in all communications.
You submitted file C:\classes\python\cgi-bin\submitfile.py
Filesize: 2020 bytes

Maintained by John Loomis, updated Sun Mar 23 15:17:09 2008

File Submissions

FieldStorage class

FieldStorage objects