Step 05 tool use
Now I understand the flow better. Let me trace through a GET request:
1. `requests.get('http://amazon.com')`
2. → `api.get()` → `api.request('get', url)` → creates Session, calls `session.request('get', url)`
3. In `session.request()`:
- `data` is None (not passed)
- Creates `Request()` with `req.data = data` → so `req.data = None`
- Calls `req.prepare()`
4. In `Request.prepare()`:
- `p.prepare_body(self.data, self.files)` where `self.data = None`
5. In `prepare_body(data=None, files=None)`:
- `body = None`, `length = None`, `is_stream = False`
- `is_stream = all([hasattr(None, '__iter__'), not isinstance(None, basestring), not isinstance(None, dict)])` → `hasattr(None, '__iter__')` is False → `is_stream = False`
- Goes to else branch:
- `files` is None/empty → skip
- `data` is None → skip (since `if data:` is False)
- `self.prepare_content_length(body)` where body is None
6. In `prepare_content_length(body=None)`:
- `self.headers['Content-Length'] = '0'` ← **BUG! This always sets Content-Length to '0' even when body is None**
The issue is that `prepare_content_length` always sets `Content-Length` header. For GET requests with no body, it sets `Content-Length: 0`, which causes issues with servers like Amazon that reject GET requests with Content-Length header.
The fix should be: only set Content-Length when there's actually a body. If body is None and there's no explicit Content-Length, we should not add it.
Let me also check what happens in `prepare_body` more carefully. The `data` default in `Request.__init__` is `dict()`, but when called from `session.request()`, `data` is set explicitly to `None` (since it's not passed). So in `prepare_body`:
```python
def prepare_body(self, data, files):
body = None
...
is_stream = all([
hasattr(data, '__iter__'),
not isinstance(data, basestring),
not isinstance(data, dict)
])
...
if is_stream:
...
else:
if files:
...
else:
if data:
body = self._encode_params(data)
...
self.prepare_content_length(body) # body is None here for GET
```
So `prepare_content_length` is called with `body=None`, and it unconditionally sets `Content-Length: 0`.
The fix is straightforward: `prepare_content_length` should only set `Content-Length` if there's actually a body to measure.
Let me fix this:
```python
def prepare_content_length(self, body):
if body is None:
# No body, don't set Content-Length
return
if hasattr(body, 'seek') and hasattr(body, 'tell'):
body.seek(0, 2)
self.headers['Content-Length'] = str(body.tell())
body.seek(0, 0)
else:
self.headers['Content-Length'] = str(len(body))
```
Wait, but there might be cases where someone explicitly wants Content-Length: 0. However, the issue states that for GET requests, Content-Length should not be added. The standard approach is that Content-Length is only meaningful when there's a body. A GET request with no body shouldn't have Content-Length.
But actually, I need to also think about the case where `body` is an empty string or something. If someone does a POST with empty data, they might want Content-Length: 0. Let me look more carefully.
Actually, looking at the code again:
```python
def prepare_body(self, data, files):
body = None
...
if is_stream:
...
else:
if files:
(body, content_type) = self._encode_files(files, data)
else:
if data:
body = self._encode_params(data)
...
self.prepare_content_length(body)
```
So `prepare_content_length` is called with `body` which could be None (GET/HEAD/DELETE without data), or an actual body string/bytes.
The fix should be: if body is None, we should not set the Content-Length header at all.
But wait, what about the case where someone passes `data=''` (empty string
... [truncated 728 characters]
Now I can see the bug. Let me trace through the code path for a GET request:
1. `requests.get(url)` → `session.request('GET', url)` with `data=None`
2. `prepare_body(data=None, files=None)` is called → `body = None`
3. `prepare_content_length(None)` is called, which **unconditionally** sets `self.headers['Content-Length'] = '0'` on line 1
The problem is in `prepare_content_length` — it always sets `Content-Length`, even when there's no body. For GET requests (and other requests without a body), this adds an unnecessary `Content-Length: 0` header that can cause servers like Amazon to reject the request.
Let me fix it:
edit_file{ path: "/testbed/requests/models.py", old_string: " def prepare_content_length(self, body):\n self.headers['Content-Length'] = '0'\n if hasattr(body, 'seek') and hasattr(body, 'tell'):\n …", new_string: " def prepare_content_length(self, body):\n if body is not None:\n if hasattr(body, 'seek') and hasattr(body, 'tell'):\n body.se…" }
tool result · edit_file
File /testbed/requests/models.py edited successfully.