[Sqlalchemy-tickets] Issue #3696: Documentation error in mssql+pymssql connection string (zzzeek/sqlalchemy)

[Rudolf C. <iss...@bi...>]

New issue 3696: Documentation error in mssql+pymssql connection string
https://bitbucket.org/zzzeek/sqlalchemy/issues/3696/documentation-error-in-mssql-pymssql

Rudolf Cardinal:

The docs at http://docs.sqlalchemy.org/en/latest/dialects/mssql.html#module-sqlalchemy.dialects.mssql.pymssql give the following prototype connection string for SQL Server (mssql) via pymssql:


```
#!python

mssql+pymssql://<username>:<password>@<freetds_name>?charset=utf8
```


However (with SQL Alchemy 1.0.12 via "pip install"), this fails. Traceback below. But the basic reason appears to be that the "?charset=utf8" gets incorporated into the "host" parameter.

The URL used was:
    
```
#!python

mssql+pymssql://researcher:blibble@crate_sqlserver_test?charset=utf8
```

where crate_sqlserver_test is defined in /etc/freetds/freetds.conf. Inserting a debugging print statement into DefaultDialect.connect(), in sqlalchemy/engine/default.py, where it calls

```
#!python

return self.dbapi.connect(*cargs, **cparams)

```
gives the following:


```
#!python

cargs: ()
cparams: {'password': 'blibble', 'host': 'crate_sqlserver_test?charset=utf8', 'user': 'researcher'}
```

**(note the error for host).**



```
#!python

Traceback (most recent call last):
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 1044, in _do_get
    return self._pool.get(wait, self._timeout)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/util/queue.py", line 145, in get
    raise Empty
sqlalchemy.util.queue.Empty

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "pymssql.pyx", line 635, in pymssql.connect (pymssql.c:10699)
  File "_mssql.pyx", line 1900, in _mssql.connect (_mssql.c:21951)
  File "_mssql.pyx", line 636, in _mssql.MSSQLConnection.__init__ (_mssql.c:6545)
_mssql.MSSQLDriverException: Connection to the database failed for an unknown reason.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/engine/base.py", line 2074, in _wrap_pool_connect
    return fn()
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 318, in unique_connection
    return _ConnectionFairy._checkout(self)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 713, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 480, in checkout
    rec = pool._do_get()
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 1060, in _do_get
    self._dec_overflow()
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/util/compat.py", line 184, in reraise
    raise value
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 1057, in _do_get
    return self._create_connection()
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 323, in _create_connection
    return _ConnectionRecord(self)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 449, in __init__
    self.connection = self.__connect()
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/pool.py", line 607, in __connect
    connection = self.__pool._invoke_creator(self)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/engine/strategies.py", line 97, in connect
    return dialect.connect(*cargs, **cparams)
  File "/home/rudolf/venvs/crate/lib/python3.4/site-packages/sqlalchemy/engine/default.py", line 387, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "pymssql.pyx", line 644, in pymssql.connect (pymssql.c:10856)
pymssql.InterfaceError: Connection to the database failed for an unknown reason.

```