Develop Reference

Error: trying to redefine a primary key as non-primary key

I'm using the dataset library to attempt to back up a postgres database into an sqlite file. The code I'm running goes as follows:
local_db = "sqlite:///backup_file.db"
with dataset.connect(local_db) as save_to:
with dataset.connect(postgres_db) as download_from:
for row in download_from['outlook']:
save_to['outlook'].insert(row)
If I print one row of the table, it looks like this:
OrderedDict([
('id', 4400),
('first_sighting', '2014-08-31'),
('route', None),
('sighted_by', None),
('date', None)
])
However, when I get to the line save_to['outlook'].insert(row) I get an error with the following stack trace:
Traceback (most recent call last):
File "/home/anton/Development/Python/TTC/backup_db.py", line 25, in <module>
save_to['outlook'].insert(dict(row))
File "/home/anton/.virtualenvs/flexity/lib/python3.6/site-packages/dataset/table.py", line 79, in insert
row = self._sync_columns(row, ensure, types=types)
File "/home/anton/.virtualenvs/flexity/lib/python3.6/site-packages/dataset/table.py", line 278, in _sync_columns
self._sync_table(sync_columns)
File "/home/anton/.virtualenvs/flexity/lib/python3.6/site-packages/dataset/table.py", line 245, in _sync_table
self._table.append_column(column)
File "/home/anton/.virtualenvs/flexity/lib/python3.6/site-packages/sqlalchemy/sql/schema.py", line 681, in append_column
column._set_parent_with_dispatch(self)
File "/home/anton/.virtualenvs/flexity/lib/python3.6/site-packages/sqlalchemy/sql/base.py", line 431, in _set_parent_with_dispatch
self._set_parent(parent)
File "/home/anton/.virtualenvs/flexity/lib/python3.6/site-packages/sqlalchemy/sql/schema.py", line 1344, in _set_parent
self.key, table.fullname))
sqlalchemy.exc.ArgumentError: Trying to redefine primary-key column 'id' as a non-primary-key column on table 'outlook'
Any ideas as to what I'm doing wrong? I've tried this in python 2.7.14 and 3.6.3

Assuming you have a schema and table made for "outlook", did you make a PK field? Did you let sqlite decide which field to make a PK field?
It is highly that you are trying to insert id twice. Once, sqlite is inserting itself, and other comes from the other table records.

I figured it out! So, the trick is that by default the database library makes tables with an auto-incrementing integer primary-key. But, my data already has an 'id' column. In order to avoid this problem, I should define my table before I try to add lines to it, and define it with no primary key as follows:
with dataset.connect(local_db) as save_to:
with dataset.connect(postgres_db) as download_from:
table_to_save_to = save_to.create_table('outlook', primary_id=False)
for row in download_from['outlook']:
table_to_save_to.insert(row)
By doing .create_table(table_name, primary_key=False) I can make sure that i can insert my own id values into the table.
I found this solution by reading the docs.

python-memcached : Unable to memcache a mysql output. ( UnpickleableError: Cannot pickle objects )

For some reason memcache does not seem to like
result
in this following code
db.query("select * from TABLE order by ID desc limit 70")
result = db.store_result()
m.set('1',result,60)
This is the error in apache error_log:
m.set('1',result,60)
File "/usr/lib/python2.6/site-packages/memcache.py", line 466, in set
return self._set("set", key, val, time, min_compress_len)
File "/usr/lib/python2.6/site-packages/memcache.py", line 639, in _set
store_info = self._val_to_store_info(val, min_compress_len)
File "/usr/lib/python2.6/site-packages/memcache.py", line 615, in _val_to_store_info
pickler.dump(val)
UnpickleableError: Cannot pickle objects
Something is probably going on with the "result".
otherwise instead of "result".. something else such as..
m.set('1','test',60)
works just fine.

store_result instructs MySQL to store the result of your query locally, and returns a reference to that "result object". It does not actually return a list of rows.
To actually get the rows:
rows = result.fetch_row(maxrows=0) # Actually fetches all the rows
m.set('1', rows, 60)
Now, it'd be best to instantiate a cursor than to use _mysql directly.

SQLAlchemy: successful insertion but then raises an exception

I am running SQLAlchemy against FirebirdSQL, and when I execute an insert command in my project, SQLAlchemy is raising an exception on returning from executing against the connection. However, the insert query is being constructed and executed successfully. Querying the database shows that the items are actually being inserted correctly.
Edit: I'm digging down into the fbcore.py module now, and checking the value of value and vartype indicates that the issue is probably how the SEQUENCE item used to generate the primary key ID is returning its data is at issue. The vartype is SQL_LONG, but the actual value is [<an integer>] where <an integer> is the value returned by a sequence generator I created to auto-increment the primary key (e.g. [14]). This suggests to me that the problem should be resolved by fixing that, though I'm not sure how to do it. The generator appears to be working correctly within the database itself, but causing problems when returned to SQLAlchemy.
See below for my existing implementation and the stack trace for details.
My code:
class Project:
# (I've snipped project instantiation, where engine connection, table, etc. are configured)
def save_project(self, id_=None, title=None, file_name=None, file_location=None):
# Build the dictionary of values to store
values = {}
if title is not None:
values['title'] = title
if file_name is not None:
values['file_name'] = file_name
if file_location is not None:
values['file_location'] = file_location
# Simplification: I account for the case that there *is* data---skipping that here
# Execute the correct kind of statement: insert or settings_update.
if id_ is None:
statement = self.table.insert()
else:
statement = self.table.update().where(self.table.c.id == id_)
result = self.connection.execute(statement, values)
# If we inserted a row, get the new primary key. Otherwise, return
# the one specified by the user; it does not change on settings_update.
project_id = result.inserted_primary_key if result.is_insert else id_
The traceback:
File "/Users/chris/development/quest/workspace/my_project/data/tables.py", line 350, in save_project
result = self.connection.execute(statement, values)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/engine/base.py", line 720, in execute
return meth(self, multiparams, params)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/sql/elements.py", line 317, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/engine/base.py", line 817, in _execute_clauseelement
compiled_sql, distilled_params
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/engine/base.py", line 947, in _execute_context
context)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/engine/base.py", line 1111, in _handle_dbapi_exception
util.reraise(*exc_info)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/util/compat.py", line 168, in reraise
raise value
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/engine/base.py", line 940, in _execute_context
context)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/sqlalchemy/dialects/firebird/kinterbasdb.py", line 106, in do_execute
cursor.execute(statement, parameters or [])
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/fdb/fbcore.py", line 3323, in execute
self._ps._execute(parameters)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/fdb/fbcore.py", line 2991, in _execute
self.__Tuple2XSQLDA(self._in_sqlda, parameters)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/fdb/fbcore.py", line 2782, in __Tuple2XSQLDA
sqlvar.sqlscale)
File "/Users/chris/.virtualenvs/my_project/lib/python3.3/site-packages/fdb/fbcore.py", line 2266, in _check_integer_range
if (value < vmin) or (value > vmax):
TypeError: unorderable types: list() < int()
I'm not yet sufficiently familiar with SQLAlchemy's to see why this is an issue; the style of my statement is pretty much identical to that in the tutorial. This appears to be an issue with how the parameters are being passed – possibly something about using a dict rather than keyword arguments? But there's nothing in the docs on how to handle parameters that suggests I have anything amiss here – it seems right from what I'm seeing there.
I've also tried this with self.table.insert().values(values) rather than passing the values term to the execute method, with the same results (as I would expect).
Edit: I note from reading the docstring on execute in fbcore.py that it raises a TypeError when the parameters passed to the method are not given either as a list or a tuple. Is this a change that is not yet reflected in the documentation?
Edit 2: As a comment notes, the stack trace indicates that it's running against the kinterbasdb driver, though I have explicitly configured the engine to run using fdb. This is also confusing to me.

As I might have expected, especially once I discovered that the issue was that the row was being inserted as expected but then called with an UPDATE function shortly after, the problem was some related code. I was returning the result as project_id (as you can see in the code above), and for an entirely unrelated reason (having to do with Blinker signals) the method was getting called again, with the returned value of project_id, which I had set thus:
project_id = result.inserted_primary_key if result.is_insert else id_
The correct version of this line is only slightly different:
project_id = result.inserted_primary_key[0] if result.is_insert else id_
From the SQLAlchemy docs (emphasis mine):
Return the primary key for the row just inserted.
The return value is a list of scalar values corresponding to the list of primary key columns in the target table.
The return value here has to be a list because primary keys can be a combination of more than one field in the database. (This should have been obvious to me; it's obvious I haven't done serious database work in over a year.) Since the primary key in this case is a single value, I just chose that value and returned it, and the problem is resolved.
Of course, now I have to go hunt down that Blinker signal issue—this method shouldn't be getting called twice—but c'est la vie...

I have been going over the SQL Alchemy documentation, and I am wondering if you should be doing:
if id_ is None:
statement = self.table.insert()
else:
statement = self.table.update().where(self.table.c.id == id_)
statement = statement.values(title=title, file_name=file_name, file_location=file_location)
result = self.connection.execute(statement)
That is: instead of passing the dictionary to the execute, make it part of the statement (as shown by the Insert Expressions).

Python pypyodbc how do I insert variables to the execute statement?

I am working with Python 3.3, pypyodbc 1.2.1, and a Quickbooks Enterprise 12 company file being access over Flexquarters QODBC version 14. I'm new to programming and python, so still learning :) I can run a query using the pypyodbc examples just fine, and produces expected results.
Notice the hardcoded email address in the execute. This works as expected:
def get_customer_id(search_col,search_str):
'''(str,str) --> str
>>>get_customer_id(email, foo#foo.com)
80000001-1385782702
'''
cur.execute("SELECT listid FROM CUSTOMER WHERE email='foo#foo.com'")
for row in cur.fetchall():
for field in row:
return field
If I try to do the same thing using the parameters that I am reading from the pypyodbc documentation, I throw an error. I'm having problems with the quotes, and parameter markers I think.
def get_customer_id(search_col,search_str):
'''(str,str) --> str
>>>get_customer_id(email, foo#foo.com)
80000001-1385782702
'''
cur.execute("SELECT listid FROM CUSTOMER WHERE email=?",(search_str,))
for row in cur.fetchall():
for field in row:
return field
Trying to be more pythonistic? I really want to reuse the function to search different columns. Something like:
cur.execute("SELECT listid FROM CUSTOMER WHERE search_str=search_col")
I have looked at a few other threads, and most of them seem to just be dealing with the parameter, and not the column to search. Can anyone help me learn this?
PS forgot to include the traceback:
Traceback (most recent call last):
File "C:\Users\Mike\Documents\Projects\qb_sync\quickbooks.py", line 32, in <module>
print(get_customer_id('email','foo#foo.com'))
File "C:\Users\Mike\Documents\Projects\qb_sync\quickbooks.py", line 27, in get_customer_id
cur.execute("SELECT listid FROM CUSTOMER WHERE email=?",[search_str,])
File "C:\Python\lib\site-packages\pypyodbc.py", line 1457, in execute
self._BindParams(param_types)
File "C:\Python\lib\site-packages\pypyodbc.py", line 1420, in _BindParams
check_success(self, ret)
File "C:\Python\lib\site-packages\pypyodbc.py", line 982, in check_success
ctrl_err(SQL_HANDLE_STMT, ODBC_obj.stmt_h, ret, ODBC_obj.ansi)
File "C:\Python\lib\site-packages\pypyodbc.py", line 960, in ctrl_err
raise Error(state,err_text)
pypyodbc.Error: ('HY004', '[HY004] [Microsoft][ODBC Driver Manager] SQL data type out of range')
[Finished in 1.7s]

I think the use of
cur.execute("""SELECT listid FROM CUSTOMER WHERE ?=?""",[column, email])
can not be accepted by database engine rather than pypyodbc or any other odbc interface. It's the database engine refuse to accept the query for the use of parameter on column names.
Probably you would have to try this instead to reuse the function:
# First construct your dynamic query for the targeted column
sql = """SELECT listid FROM CUSTOMER WHERE %s=?""" %(column)
# Then provide the dynamic value for the dynamic query string
cur.execute(sql, (value,))

Python 3 also has the str.format() method which will do string replacement on {index} items within your string. This is useful if you have many values to inject into your strings like:
myStr = "I like {0} and {1}, but I don't like {2}.".format("apples","bananas","spinach")
myStr
"I like apples and bananas, but I don't like spinach."
# First construct your dynamic query for the targeted column
sql = """SELECT listid FROM CUSTOMER WHERE {0}=?""".format(column)
# Then provide the dynamic value for the dynamic query string
cur.execute(sql, (value,))
It's worth noting that this method of replacing values in a string query can be subject to sql injection.
The safer way to do this would be with parameterized stored procs.

I got 1/2 the answer so far. This works for one parameter, IF I format the string before calling the function;
print(get_custid_email(b'foo#foo.org'))
cur.execute("""SELECT listid FROM CUSTOMER WHERE email=?""",[email])
I still can't get it to do the same thing with column name though.
print(get_custid_email(b'email',b'foo#foo.org'))
cur.execute("""SELECT listid FROM CUSTOMER WHERE ?=?""",[column, email])
That throws a differnt error:
Traceback (most recent call last):
File "C:\Users\Mike\Documents\Projects\qb_sync\quickbooks.py", line 34, in <module>
print(get_custid_email(b'wendy.lindsay#gmail.com'))
File "C:\Users\Mike\Documents\Projects\qb_sync\quickbooks.py", line 29, in get_custid_email
cur.execute("""SELECT listid FROM CUSTOMER WHERE ?=?""",['email',email])
pyodbc.ProgrammingError: ('42S00', '[42S00] [QODBC] Data type of parameter cannot be determined (11023) (SQLPrepare)')

SQLAlchemy IntegrityError

I'm having a problem using SQLAlchemy with PySide(PyQt). I'm trying to pop-up a QtGui.QDialog, but when I do this SQLAlchemy throws an exception:
Traceback (most recent call last):
File "C:\Python27\lib\site-packages\preo\preodb\dbviewandmodel.py", line 32, in rowCount
return len(self.rows())
File "C:\Python27\lib\site-packages\preo\preodb\dbviewandmodel.py", line 30, in rows
return self.tableobj.query.all()
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\query.py", line 1579, in all
return list(self)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\query.py", line 1688, in __iter__
self.session._autoflush()
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\session.py", line 862, in _autoflush
self.flush()
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\session.py", line 1388, in flush
self._flush(objects)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\session.py", line 1469, in _flush
flush_context.execute()
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\unitofwork.py", line 302, in execute
rec.execute(self)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\unitofwork.py", line 446, in execute
uow
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\orm\mapper.py", line 1878, in _save_obj
execute(statement, params)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\engine\base.py", line 1191, in execute
params)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\engine\base.py", line 1271, in _execute_clauseelement
return self.__execute_context(context)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\engine\base.py", line 1302, in __execute_context
context.parameters[0], context=context)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\engine\base.py", line 1401, in _cursor_execute
context)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\engine\base.py", line 1394, in _cursor_execute
context)
File "C:\Python27\lib\site-packages\sqlalchemy-0.6.6-py2.7.egg\sqlalchemy\engine\default.py", line 299, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.IntegrityError: (IntegrityError) ('23000', "[23000] [Microsoft][ODBC
SQL Server Driver][SQL Server]Violation of UNIQUE KEY
constraint 'UQ__users__F3DBC5720DAF0CB0'. Cannot insert duplicate key in
object 'dbo.users'. (2627) (SQLExecDirectW); [01000] [Microsoft][ODBC SQL Server
Driver][SQL Server]The statement has been terminated. (3621)") u'INSERT INTO users
(username, fullname, email, passwordmd5) OUTPUT inserted.id VALUES (?, ?, ?, ?)'
(None, None, None, None)
This is particularly troubling because I have no code, anywhere, that even attempts to insert records into SQL; I am only ever attempting to query data from the database. In fact, my DB model is read-only with respect to what PySide/PyQt are doing (i.e., I'm using a QtGui.QTableView model/view and there is no insertRows function in that model).
I have no idea what's going on or how to solve it - again, I have no code to modify SQL records at all, but still SQLAlchemy attempts to be inserting blank records into one of my SQL tables. All I can see, in the background, is the QTableView data model is querying the database A LOT. It just seems that when I popup this QDialog (which does have some code in it to query some table column) this error is thrown. Oddly, this isn't consistent, sometime the popup appears first before the exception, sometimes the popup appears after the exception. Under normal circumstances, the QTableView data model works great, just not when I popup this dialog (and ironically, the popup isn't using any QTableView at all, just standard widgets like QLineEdit, QTextEdit, etc.)
If it helps, I'm using Python 2.7 with SQLAlchemy 0.6.6 (also with Elixir 0.7.1), and PySide 1.0.0 (and PyQt4 4.8.3). I'm on Windows 7 using SQL 2008 R2 (Express). And yes, I've tried rebooting the PC, but the problem still occurs after a reboot. I'm reluctant to post more code because I have a lot of it in this particular project and I can't nail down the problem anything specific.
I'm hoping someone might know of oddities in SQLAlchemy and/or PyQt that might be related to this. I'm also hoping I can continue using SQLAlchemy as I have a large data model built; I'm reluctant, at this point, to abandon this and use PyQt's SQL features.

I've managed to make this problem go away, but it's still not really clear to me why SQLAlchemy was trying to insert rows in my database - that really bothers me, but it's not happening anymore.
At any rate, what was, I think, happening, was related to my SQLAlchemy data model and the way I was accessing it, here is a snippet of that model:
from elixir import *
metadata.bind = 'mssql+pyodbc://username:password/dbname'
metadata.bind.echo = False
class Users(Entity):
using_options(tablename = 'users')
username = Field(String(50), unique=True)
fullname = Field(String(255))
email = Field(String(255))
passwordmd5 = Field(String(32))
def __repr__(self):
return "<Users ({})({})({})>".format(self.username, self.fullname, self.email)
def prettyname(self):
return {'username':'User Name', 'fullname':'Full Name', 'email':'Email Address', 'passwordmd5':'$hidden$'}
In my code I needed a way of getting 'pretty' label names for a GUI without having to hard code this in a GUI (I've been trying to create a dynamic way of building GUI forms). So, I added the 'prettyname' method to my data model to give me some application specific metadata in that data model. All I'm doing is returning a dictionary of items.
I had a secondary problem in that sometimes I needed to get this data from the class instance for Users and sometimes for a query result for Users (for example, Users.get_by(id=1)). As it turned out, retrieving this data had to be done in two ways. In the class instances I had to get the value this way:
prettyname = Users().prettyname()['username']
But when I was using query results it was:
prettyname = queryresult.prettyname()['username']
SQLAlchemy seems to have a real problem when I was using the former method (the class instance method) - as this was being used everytime I was seeing the crash. When I was using the latter instance I was never seeing a crash. Still, I needed access to that metadata in the class instance.
The fix, or should I say what turned out to fix this came from another Stackoverflow article (thank you everyone at Stackoverflow - I'd be nothing without you). I changed the structure of the dbmodel:
class Users(Entity):
using_options(tablename = 'users')
username = Field(String(50), unique=True, info={'prettyname':'User Name'})
fullname = Field(String(255), info={'prettyname':'Full Name'})
email = Field(String(255), info={'prettyname':'Email Address'})
passwordmd5 = Field(String(32), info={'hidden':True})
def __repr__(self):
return "<Users ({})({})({})>".format(self.username, self.fullname, self.email)
This allows me to use a common method of introspection to get the dictionary data in the info argument, regardless if I'm looking at a class instance, or a query result. In this case I use the '.table' method of either the class or query result, then get the column that I need (.c), then use the .info method of that column to return the dictionary.
Whatever the case, now SQLAlchemy no longer tries to arbitrarily insert rows in the database anymore.