How do you convert a string obj to a file obj?

[Matthew Thorley]

I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew

[John Abel]

Matthew Thorley wrote:

I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew

fileObj = StringIO.StringIO()
fileObj.write( data )

J

[Matthew Thorley]

John Abel wrote:

Matthew Thorley wrote:

I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew

fileObj = StringIO.StringIO()
fileObj.write( data )

J

I gave that a shot but got this error? Perhaps I misunderstood what kind
of object I needed. Any thoughts?

AttributeError: StringIO instance has no attribute 'rfind'

[Esben Pedersen]

Matthew Thorley wrote:

I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew

value.file is a file object. Why don't you give that as an argument?

/Esben

[Matthew Thorley]

Esben Pedersen wrote:

Matthew Thorley wrote:

I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew

value.file is a file object. Why don't you give that as an argument?

/Esben

Ok I tried that but I still get this error. Any clue what I need to do?

AttributeError: 'file' object has no attribute 'rfind'
thanks
-Matthew

[Peter Otten]

Matthew Thorley wrote:

Esben Pedersen wrote:

Matthew Thorley wrote:

I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew

value.file is a file object. Why don't you give that as an argument?

/Esben

Ok I tried that but I still get this error. Any clue what I need to do?

AttributeError: 'file' object has no attribute 'rfind'

str has an rfind() method while file has not:

file.rfind Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: type object 'file' has no attribute 'rfind' str.rfind

<method 'rfind' of 'str' objects>

So "the function" seems to expect a string rather than a file. Or perhaps
there's an (evil) isinstance(param, file) check somewhere that triggers
param to be treated as a filename. Absent further information, only you can
find out.

Peter

[Matthew Thorley]

Peter Otten wrote:

Matthew Thorley wrote:

Esben Pedersen wrote:

Matthew Thorley wrote:
I'm writing a web app whereby a user uploads a tar acrhive which is then
opened and processed. My web form reads the file like this:

while 1:
data = value.file.read(1024 * 8) # Read blocks of 8KB at a time
if not data: break

which leaves me with data as a string obj. The problem that I have is
that the function that processes the archive expects a file object. So
far the only solution I have found it to write the file to disk and then
read it back.

Is there an easy way to convert data, in the example above into a file
object?

Thanks
-Matthew
value.file is a file object. Why don't you give that as an argument?

/Esben

Ok I tried that but I still get this error. Any clue what I need to do?

AttributeError: 'file' object has no attribute 'rfind'

str has an rfind() method while file has not:

file.rfind
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: type object 'file' has no attribute 'rfind'
str.rfind

<method 'rfind' of 'str' objects>

So "the function" seems to expect a string rather than a file. Or perhaps
there's an (evil) isinstance(param, file) check somewhere that triggers
param to be treated as a filename. Absent further information, only you can
find out.

Peter

Ok you're right. tarfile.open expects a string; the path to the file
open. I thought that I had tried it with open file objects but I guess I
was mistaken.

Thanks all for the help
-Matthew

[Peter Otten]

Matthew Thorley wrote:

Ok you're right. tarfile.open expects a string; the path to the file
open. I thought that I had tried it with open file objects but I guess I
was mistaken.

tarfile.open()? That would have been important information in your initial
post.

It would have been even better to just type help(tarfile.open) at the
interactive prompt (remember that next time). Reading the documentation for
you:

"""
open([name[, mode [, fileobj[, bufsize]]]])

....

If fileobj is specified, it is used as an alternative to a file object
opened for name.
"""

So try passing value.file as the third parameter.

Peter