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testing postgres db python

I don't understand how to test my repositories.
I want to be sure that I really saved object with all of it parameters into database, and when I execute my SQL statement I really received what I am supposed to.
But, I cannot put "CREATE TABLE test_table" in setUp method of unittest case because it will be created multiple times (tests of the same testcase are runned in parallel). So, as long as I create 2 methods in the same class which needs to work on the same table, it won't work (name clash of tables)
Same, I cannot put "CREATE TABLE test_table" setUpModule, because, now the table is created once, but since tests are runned in parallel, there is nothing which prevents from inserting the same object multiple times into my table, which breakes the unicity constraint of some field.
Same, I cannot "CREATE SCHEMA some_random_schema_name" in every method, because I need to globally "SET search_path TO ..." for a given Database, so every method runned in parallel will be affected.
The only way I see is to create to "CREATE DATABASE" for each test, and with unique name, and establish a invidual connection to each database.. This looks extreeeemly wasteful. Is there a better way?
Also, I cannot use SQLite in memory because I need to test PostgreSQL.

The best solution for this is to use the testing.postgresql module. This fires up a db in user-space, then deletes it again at the end of the run. You can put the following in a unittest suite - either in setUp, setUpClass or setUpModule - depending on what persistence you want:
import testing.postgresql
def setUp(self):
self.postgresql = testing.postgresql.Postgresql(port=7654)
# Get the url to connect to with psycopg2 or equivalent
print(self.postgresql.url())
def tearDown(self):
self.postgresql.stop()
If you want the database to persist between/after tests, you can run it with the base_dir option to set a directory - which will prevent it's removal after shutdown:
name = "testdb"
port = "5678"
path = "/tmp/my_test_db"
testing.postgresql.Postgresql(name=name, port=port, base_dir=path)
Outside of testing it can also be used as a context manager, where it will automatically clean up and shut down when the with block is exited:
with testing.postgresql.Postgresql(port=7654) as psql:
# do something here

Calling python script in web2py framework over webserver

I have NGINX UWSGI and WEB2PY installed on the server. Web2py application performing only one function by accessing the database and printing rows in the table.
def fetch():
import psycopg2
conn = psycopg2.connect(database="postgres",
user="postgres",
password="qwerty",
host="127.0.0.1")
cur = conn.cursor()
cur.execute("SELECT id, name from TEST")
rows = cur.fetchall()
conn.close()
return rows
When the function is called locally the table contents is returned.
But when I'm trying to call the function from remote machine I get an internal error 500.
One more interesting thing, is when function looks like this:
def hello():
return 'hello'
String 'hello' is returned. Starting adding it an import directive immediately causes error page to be generated.
Can any one please suggest the proper application syntax/logic?

My guess is that your MySQL service doesn't allow remote access. Could you check your MySQL configuration?
vim /etc/mysql/my.cnf
Comment out the following lines.
#bind-address = 127.0.0.1
#skip-networking
If there is no skip-networking line in your configuration file, just add it and comment out it.
And then restart the mysql service.
service mysql restart

Forgive the stupid question but have you checked if the module is available on your server?
When you say that the error appears in your hello function as soon as you try to import, it's the same directive import psycopg2?
Try this:
Assuming that fetch() it's defined on controllers/default.py
open folder views/default and create a new file called fetch.html
paste this inside
{{extend 'layout.html'}}
{{=rows}}
fetch.html is a view or a template if you prefer
Modify fetch() to return a dictionary with rows for the view to print
return dict(rows=rows)
this is very basic tough, you can find more information about basic steps in the book -> http://www.web2py.com/books/default/chapter/29/03/overview#Postbacks

Python mysql doesn't see data change in database

i need some help with python an mysql.
I have the following code, which is executing in infinite loop:
db = MySQLdb.connect("127.0.0.1","user","password","dbname" )
while True:
cursor = db.cursor()
cursor.execute("SELECT * FROM requests WHERE status <> 'Finished'")
all_pending_requests = cursor.fetchall()
cursor.close()
And that works fine the first time i run it. But when i go to a tool like mysql workbench or i type it myself in in terminal, i update some rows and set their status to something that is not "Finished". So by doing that the next time the loop executes i should get those rows as a result but i get nothing. Do you guys now why this is happening maybe?
Thanks for help.

I am not certain but would assume that you are using InnoDB storage engine in MySQL and MySQLdb version >=1.2.0. You need to commit before the changes are being reflected. As of version 1.2.0, MySQLdb disables auto-commit by default. Confirmation of the same is here. Try adding db.commit() as the last line in the loop.

UPDATE statement on Access database fails silently under pyodbc

I have a problem with a simple UPDATE statement. I wrote a Python tool which creates a lot of UPDATE statements and after creating them I want to execute them on my Access database but it doesn't work This is one statement for example:
UPDATE FCL_B_COVERSHEET_A SET BRANCH = 0 WHERE OBJ_ID = '1220140910132011062005';
The statement syntax is not the problem. I tested it and it works.
This next code snippet shows the initialization for the connect object.
strInputPathMDB = "C:\\Test.mdb"
DRV = '{Microsoft Access Driver (*.mdb)}';
con = pyodbc.connect('Driver={0};Dbq={1};Uid={2};Pwd={3};'.format(DRV,strInputPathMDB,"administrator",""))
After that I wrote a method which execute one SQL statement
def executeSQLStatement(conConnection, strSQL):
arcpy.AddMessage(strSQL)
cursor = conConnection.cursor()
cursor.execute(strSQL)
conConnection.commit()
and if I execute this code everything seems to work - no error message or anything like that - but also the data is not updated and I don't know what I'm doing wrong ...
for strSQL in sqlStateArray:
executeSQLStatement(con, strSQL)
con.close()
I hope you understand what my problem is. Thanks for your help.
Chris

The issue here was that the .mdb file was in the root folder of the C: drive. Root folders often restrict normal users to read-only access so the database file was being opened as read-only. Moving the .mdb file to a public folder solved the problem.

Print the actual query MySQLdb runs?

I'm looking for a way to debug queries as they are executed and I was wondering if there is a way to have MySQLdb print out the actual query that it runs, after it has finished inserting the parameters and all that? From the documentation, it seems as if there is supposed to be a Cursor.info() call that will give information about the last query run, but this does not exist on my version (1.2.2).
This seems like an obvious question, but for all my searching I haven't been able to find the answer.

We found an attribute on the cursor object called cursor._last_executed that holds the last query string to run even when an exception occurs. This was easier and better for us in production than using profiling all the time or MySQL query logging as both of those have a performance impact and involve more code or more correlating separate log files, etc.
Hate to answer my own question but this is working better for us.

You can print the last executed query with the cursor attribute _last_executed:
try:
cursor.execute(sql, (arg1, arg2))
connection.commit()
except:
print(cursor._last_executed)
raise
Currently, there is a discussion how to get this as a real feature in pymysql (see pymysql issue #330: Add mogrify to Cursor, which returns the exact string to be executed; pymysql should be used instead of MySQLdb)
edit: I didn't test it by now, but this commit indicates that the following code might work:
cursor.mogrify(sql, (arg1, arg2))

For me / for now _last_executed doesn't work anymore. In the current version you want to access
cursor.statement.
see: https://dev.mysql.com/doc/connector-python/en/connector-python-api-mysqlcursor-statement.html

For mysql.connector:
cursor.statement
https://dev.mysql.com/doc/connector-python/en/connector-python-api-mysqlcursor-statement.html

cursor.statement and cursor._last_executed raised AttributeError exception
cursor._executed
worked for me!

One way to do it is to turn on profiling:
cursor.execute('set profiling = 1')
try:
cursor.execute('SELECT * FROM blah where foo = %s',[11])
except Exception:
cursor.execute('show profiles')
for row in cursor:
print(row)
cursor.execute('set profiling = 0')
yields
(1L, 0.000154, 'SELECT * FROM blah where foo = 11')
Notice the argument(s) were inserted into the query, and that the query was logged even though the query failed.
Another way is to start the server with logging turned on:
sudo invoke-rc.d mysql stop
sudo mysqld --log=/tmp/myquery.log
Then you have to sift through /tmp/myquery.log to find out what the server received.

I've had luck with cursor._last_executed generally speaking, but it doesn't work correctly when used with cursor.executemany(). That drops all but the last statement. Here's basically what I use now in that instance instead (based on tweaks from the actual MySQLDb cursor source):
def toSqlResolvedList( cursor, sql, dynamicValues ):
sqlList=[]
try:
db = cursor._get_db()
if isinstance( sql, unicode ):
sql = sql.encode( db.character_set_name() )
for values in dynamicValues :
sqlList.append( sql % db.literal( values ) )
except: pass
return sqlList

This read-only property returns the last executed statement as a string. The statement property can be useful for debugging and displaying what was sent to the MySQL server.
The string can contain multiple statements if a multiple-statement string was executed. This occurs for execute() with multi=True. In this case, the statement property contains the entire statement string and the execute() call returns an iterator that can be used to process results from the individual statements. The statement property for this iterator shows statement strings for the individual statements.
str = cursor.statement
source: https://dev.mysql.com/doc/connector-python/en/connector-python-api-mysqlcursor-statement.html

I can't say I've ever seen
Cursor.info()
In the documentation, and I can't find it after a few minutes searching. Maybe you saw some old documentation?
In the mean time you can always turn on MySQL Query Logging and have a look at the server's log files.

assume that your sql is like select * from table1 where 'name' = %s
from _mysql import escape
from MySQLdb.converters import conversions
actual_query = sql % tuple((escape(item, conversions) for item in parameters))