python : post data within stringIO through poster?

Question

``` params = {'file': open("test.txt", "rb"), 'name': 'upload test'} datagen, headers = poster.encode.multipart_encode(params) request = urllib2.Request(upload_url, datagen, headers) result = urllib2.urlopen(request) ``` I use poster library to POST for HTTP. It works well. I'm satisfied with that. But I want to try something. As you see above, to send file data, I have to OPEN a file. But is there any way not to make a real file to do that? We can use a STREAM, like `StringIO`, to deal with data like a file, right? But, I don't know about `poster` deeply. So, I want to know the method to use a STREAM with `poster`. ADDED Actually, I tried to POST image data. I wrote this below ``` from PyQt4 import QtCore, QtGui from poster.encode import multipart_encode from poster.streaminghttp import register_openers import urllib2, os register_openers() app = QtGui.QApplication(sys.argv) pixmap = QtGui.QPixmap("c:/test_img.png") byte_array = QtCore.QByteArray() buffer = QtCore.QBuffer(byte_array)…

Accepted Answer

The `file` param is where you pass the file object. So, what happens if you pass a file-like object instead?

```
>>> params = {'file': cStringIO.StringIO('upload test data'), 'name': 'upload test'}
>>> datagen, headers = poster.encode.multipart_encode(params)
>>> headers
{'Content-Length': '317', 'Content-Type': 'multipart/form-data; boundary=0c56082b1e134424a918b2b083391467'}
```

Looks like it worked.

What does the documentation say?

Values are either strings parameter values, or file-like objects to use as the parameter value. The file-like objects must support .read() and either .fileno() or both .seek() and .tell().

So, you can use `StringIO` objects because they support `seek()` and `tell()`.

But you don't have to. You should be able to just use the raw string. Let's try it and see:

```
>>> params = {'file': 'upload test data', 'name': 'upload test'}
>>> datagen, headers = poster.encode.multipart_encode(params)
>>> headers
{'Content-Length': '317', 'Content-Type': 'multipart/form-data; boundary=0c56082b1e134424a918b2b083391467'}
```

Look at that, the documentation is correct.

python : post data within stringIO through poster?

Solution

Problem