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https://issues.apache.org/jira/browse/COUCHDB-2583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14322718#comment-14322718
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Samuel Tardieu commented on COUCHDB-2583:
-----------------------------------------
Concerning the content-type for the empty content, I understand your point for
the general situation, but in the {{application/json}} case, the empty string
is not a valid JSON representation (while it would be for
`application/x-www-form-urlencoded` since an empty string would represent the
empty JSON object). One could object that if a content-type is present, a value
of said content should be parsable (even if it is from the empty string, which
is not possible in the JSON case).
I run the following code (which I created to try to test the issue). Note that
the local server has an {{admin:admin}} administrator set, remove the
{{Authorization}} line to check on an admin-party server.
{code:title=test.py}
#! /usr/bin/python
#
from socket import *
s = socket(AF_INET, SOCK_STREAM)
s.connect(('localhost',5984))
headers = """Host: localhost:5984
Authorization: Basic YWRtaW46YWRtaW4=
Accept: application/json"""
request = """PUT /testdb1 HTTP/1.1
%(headers)s
Content-Length: 0
PUT /testdb2 HTTP/1.1
%(headers)s
Content-Length: 0
POST /testdb1/_ensure_full_commit HTTP/1.1
%(headers)s
Content-Type: application/json
Content-Length: 2
{}
PUT /testdb3 HTTP/1.1
%(headers)s
Content-Length: 0
""" % {"headers": headers}
s.send(request)
while True:
p = s.recv(1500)
if not p:
break
print(p)
{code}
When run against my 1.6.1 server, I get:
{code:title=Output}
HTTP/1.1 412 Precondition Failed
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:34:27 GMT
Content-Type: application/json
Content-Length: 95
Cache-Control: must-revalidate
{"error":"file_exists","reason":"The database could not be created, the file
already exists."}
HTTP/1.1 412 Precondition Failed
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:34:27 GMT
Content-Type: application/json
Content-Length: 95
Cache-Control: must-revalidate
{"error":"file_exists","reason":"The database could not be created, the file
already exists."}
HTTP/1.1 201 Created
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:34:27 GMT
Content-Type: application/json
Content-Length: 53
Cache-Control: must-revalidate
{"ok":true,"instance_start_time":"1424085277160411"}
{code}
[and the test program exits because the connection has been closed from the
server side]
Note that the connection is dropped after the result from the
{{_ensure_full_commit}} method call. If I change the call to use
{{Content-Length: 0}} (instead of 2) and remove the empty JSON object, I get:
{code:title=Alternative}
HTTP/1.1 412 Precondition Failed
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:36:36 GMT
Content-Type: application/json
Content-Length: 95
Cache-Control: must-revalidate
{"error":"file_exists","reason":"The database could not be created, the file
already exists."}
HTTP/1.1 412 Precondition Failed
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:36:36 GMT
Content-Type: application/json
Content-Length: 95
Cache-Control: must-revalidate
{"error":"file_exists","reason":"The database could not be created, the file
already exists."}
HTTP/1.1 201 Created
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:36:36 GMT
Content-Type: application/json
Content-Length: 53
Cache-Control: must-revalidate
{"ok":true,"instance_start_time":"1424085277160411"}
HTTP/1.1 412 Precondition Failed
Server: CouchDB/1.6.1 (Erlang OTP/17)
Date: Mon, 16 Feb 2015 12:36:36 GMT
Content-Type: application/json
Content-Length: 95
Cache-Control: must-revalidate
{"error":"file_exists","reason":"The database could not be created, the file
already exists."}
{code}
and the program hangs there because the connection is still not dropped (as
expected) and is waiting for the next command.
> ensure_full_commit requires empty but typed content or it will unexpectedly
> drops the connection
> ------------------------------------------------------------------------------------------------
>
> Key: COUCHDB-2583
> URL: https://issues.apache.org/jira/browse/COUCHDB-2583
> Project: CouchDB
> Issue Type: Bug
> Security Level: public(Regular issues)
> Components: HTTP Interface
> Affects Versions: 1.6.1
> Reporter: Samuel Tardieu
>
> When given an non-empty (but valid) JSON content, some methods such as
> {{_ensure_full_commit}} will abruptly drop a persistent connection instead of
> waiting for a new HTTP request even though no error is signaled in CouchDB
> logs:
> {code:title=Request}
> POST /testdb1/_ensure_full_commit HTTP/1.1
> Host: localhost:5984
> Accept: application/json
> Content-Type: application/json
> Content-Length: 2
> {}
> {code}
> {code:title=Response}
> HTTP/1.1 201 Created
> Server: CouchDB/1.6.1 (Erlang OTP/17)
> Date: Mon, 16 Feb 2015 11:49:11 GMT
> Content-Type: application/json
> Content-Length: 53
> Cache-Control: must-revalidate
> {"ok":true,"instance_start_time":"1424085277160411"}
> {code}
> [connection is closed without warning by CouchDB at this point]
> To remedy that, one could try to give an empty content, but some frameworks
> (such as spray.io) will systematically omit the {{Content-Type}} header in
> this case since it makes little sense to type empty content. However, CouchDB
> will reject the request even though it does *not* want any content:
> {code:title=Request}
> POST /testdb1/_ensure_full_commit HTTP/1.1
> Host: localhost:5984
> Accept: application/json
> Content-Length: 0
> {code}
> {code:title=Response}
> HTTP/1.1 415 Unsupported Media Type
> Server: CouchDB/1.6.1 (Erlang OTP/17)
> Date: Mon, 16 Feb 2015 11:55:52 GMT
> Content-Type: application/json
> Content-Length: 78
> Cache-Control: must-revalidate
> {"error":"bad_content_type","reason":"Content-Type must be application/json"}
> {code}
> This makes it impossible to use those methods with such frameworks. CouchDB
> should not drop the connection and ignore the data if {{Content-Length}} is
> not 0, nor require that data be typed with {{application/json}} if it is
> going to ignore it anyway or if it requires it to be empty.
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