In PyCharm I created a MySQL schema using pymysql on my computer. Now I want to use Peewee to create tables and write the SQL queries. However, I always receive an error message (see below) when trying to connect to the DB.
The user has sufficient rights to create tables in the DB schema as it works flawlessly with pymysql (creating tables as well as the schema works fine).
I looked at similar questions on Stackoverflow and couldn't find a similar problem. Moreover, this problem wasn't experienced in any of the tutorials I looked at, so I'm not entirely sure what could be the culprit causing the error. Below is a minimal working example.
from peewee import*
import peewee
user = 'root'
password = 'root'
db_name = 'peewee_demo'
# The schema with the name 'peewee_demo' exists
db = MySQLDatabase(db_name, user=user, passwd=password)
class Book(peewee.Model):
author = peewee.CharField()
title = peewee.TextField()
class Meta:
database = db
db.connect() # Code fails here
Book.create_table()
book = Book(author="me", title='Peewee is cool')
book.save()
for book in Book.filter(author="me"):
print(book.title)
I would expect the above code to connect to MySQL and then create a new table in the schema "peewee_demo". But instead, the code throws an error message when trying to connect to the DB:
/usr/bin/python3.6: Relink '/lib/x86_64-linux-gnu/libsystemd.so.0' with /lib/x86_64-linux-gnu/librt.so.1' for IFUNC symbol clock_gettime'
/usr/bin/python3.6: Relink /lib/x86_64-linux-gnu/libudev.so.1' with /lib/x86_64-linux-gnu/librt.so.1' for IFUNC symbol `clock_gettime'
Do you have any ideas how to fix this issue?
Thanks in advance
As #coleifer pointed out in his comment, the error was probably related to a shared library issue in Python. After setting up a new virtual environment and installing all required packages, everything runs perfectly fine.
I just added the answer to be able to close the question. If #coleifer converts his comment into an answer, I'll delete mine and accept his.
Related
Python 3.8.8 programm with Flask 2.0.1 and Flask-SQLAlchemy 2.5.1
MySql database, collation of the tables: utf8_general_ci.
I'm using two other sqlserver DB with SQLALCHEMY_BINDS. Everything runs on Windows 10.
Some chars from select queries on the MySql DB comes wrong: "situazione è decisamente migliorata"
should be: "situazione è decisamente migliorata"
This would solve the problem:
mystring.encode('cp1252').decode('utf8')
but I need a solution at program level. I tried:
appending to SQLALCHEMY_DATABASE_URI connection string:
"?charset=utf8" or "?charset=cp1215" and others
setting app.config['MYSQL_CHARSET'] and
app.config['MYSQL_DATABASE_CHARSET'] to 'utf8', 'utf8mb4', 'latin1', 'cp1252'
...
passing a parameter to SQLAlchemy like db = SQLAlchemy(use_native_unicode="utf8"), many variations here too
No attemp worked. Please I need suggestions.
Are you looking for a way to specify per database connection encoding ?
For all connections try to use
app.config['SQLALCHEMY_ENGINE_OPTIONS'] = {'encoding': 'cp1252'}
For specific connections to different DBs you can also use engine_options:
engine = create_engine('mysql://user:password#hostname/dbname',
encoding='cp1252')
Got the solution.
The problem was not a problem.
The person who build the original database (that is quite old) coded wrong some characters.
Some of my approaches and the one suggested by olegsv, worked, I checked that debugging deep down into into sqlalchemy data structures, the driver accepted the characters encoding, but the very chars in data were themself worong.
This was unespected.
Maybe I should delete the whole question.
I have a database with a lot of nonmanaged tables which I'm using for a django app. For testing I'm wanting to use the --keepdb option so that I don't have to repopulate these tables every time. I'm using MariaDB for my database. If I don't use the keepdb option everything works fine, the test database gets created and destroyed properly.
But when I try to run the test keeping the database:
$ python manage.py test --keepdb
I get the following error:
Using existing test database for alias 'default'...
Got an error creating the test database: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'CREATE DATABASE IF NOT EXISTS test_livedb ;\n SET sql_note' at line 2")
I assume that this is an issue with a different syntax between MariaDB and MySQL. Is there anyway to get the keepdb option to work with MariaDB?
thanks very much!
For what it's worth: This bug was introduced in Django 2.0.0 and fixed in Django 2.1.3 (https://code.djangoproject.com/ticket/29827)
Two things - check out Factory Boy (for creating test data) and I would suggest checking out Pytest as well. With non-managed tables, the issue I think you'll run into is that (at least in my experience) django won't create them in the test environment and you end up running into issues because there is no migration file to create those tables (since they're unmanaged). Django runs the migration files when creating the test environment.
With Pytest you can run with a --nomigrations flag which builds your test database directly off the models (thus creating the tables you need for your unmanaged models).
If you combine Pytest and Factory Boy you should be able to come up with the ability to setup your test data so it works as expected, is repeatable and testable without issue.
I actually approach it like this (slightly hacky, but it works with our complex setup):
On my model:
class Meta(object):
db_table = 'my_custom_table'
managed = getattr(settings, 'UNDER_TEST', False)
I create the UNDER_TEST variable in settings.py like this:
# Create global variable that will tell if our application is under test
UNDER_TEST = (len(sys.argv) > 1 and sys.argv[1] == 'test')
That way - when the application is UNDER_TEST the model is marked as managed (and Pytest will create the appropriate DB table). Then FactoryBoy handles putting all my test data into that table (either in setUp of the test or elsewhere) so I can test against it.
That's my suggestion - others might have something a little more clear or cleaner.
I need to connect a MYSQL Database to Matlab in order to work with the measured data. I am using Matlab version 2014a and unfortunately don't have a Datatoolbox to acces.
I found after a lot of research following instruction:
http://hohonuuli.blogspot.com/2014/10/jdbc-and-matlab-simple-example.html
Unfortunately though it failed to get the connection to the database, I am stucked at the database.m script, while getting following error:
database
No method 'getConnection' with matching signature found for class 'java.sql.DriverManager'.
Error in database (line 29)
c = java.sql.DriverManager.getConnection('url', 'username', 'password',
'mysql-connector-java-5.1.46');
I used exactly the script in the following link above ( copy paste ) while putting my username,url,pw etc in.
I am not a programmer by any means but need to find a solution for that, if anyone can help me that would be awesome, THANK IN ADVANCE EIKE
I have transfered my project from MySQL to PostgreSQL and tried to drop the column as result of previous issue, because after I removed the problematic column from models.py and saved. error didn't even disappear. Integer error transferring from MySQL to PostgreSQL
Tried both with and without quotes.
ALTER TABLE "UserProfile" DROP COLUMN how_many_new_notifications;
Or:
ALTER TABLE UserProfile DROP COLUMN how_many_new_notifications;
Getting the following:
ERROR: relation "UserProfile" does not exist
Here's a model, if helps:
class UserProfile(models.Model):
user = models.OneToOneField(User)
how_many_new_notifications = models.IntegerField(null=True,default=0)
User.profile = property(lambda u: UserProfile.objects.get_or_create(user=u)[0])
I supposed it might have something to do with mixed-case but I have found no solution through all similar questions.
Yes, Postgresql is a case aware database but django is smart enough to know that. It converts all field and it generally converts the model name to a lower case table name. However the real problem here is that your model name will be prefixed by the app name. generally django table names are like:
<appname>_<modelname>
You can find out what exactly it is by:
from myapp.models import UserProfile
print (UserProfile._meta.db_table)
Obviously this needs to be typed into the django shell, which is invoked by ./manage.py shell the result of this print statement is what you should use in your query.
Client: DataGrip
Database engine: PostgreSQL
For me this worked opening a new console, because apparently from the IDE cache it was not recognizing the table I had created.
Steps to operate with the tables of a database:
Database (Left side panel of the IDE) >
Double Click on PostgreSQL - #localhost >
Double Click on the name of the database >
Right click on public schema >
New > Console
GL
I am trying to switch between 2 mysql servers at runtime. I do not need to maintain both connections alive all the time.
This is what I am doing
from django.conf import settings
from django.db import connection
from django.contrib.auth.models import User
connection.close()
setattr(settings, 'DATABASE_HOST', 'mysql1.com')
list1 = User.objects.all()
connection.close()
setattr(settings, 'DATABASE_HOST', 'mysql2.com')
list2 = User.objects.all()
I have the following settings.py:
DATABASE_HOST = '' # localhost
DATABASE_NAME = test
...
The database name is the same on all servers and only the content of each tables differ.
I should get list1 != list2 as the users are different on both servers.
The issue is that I always get the list of users from the default database defined in settings.py (which is running on localhost) instead of the one from mysql 1 server and then from mysql 2 server.
Any idea what I am doing wrong here?
Laurent
My guess, from the information, would be a potential error in your set DATABASE_HOST lines (in yor pseudo code above). read: "setattr(settings..."
Other than that, I'm not sure how you've configured your database to switch based on your criteria, as you've not explained this. If you are doing it by model, it may be worth considering how Django knows this, or even using external connections (manually loading the database driver and running commands by hand prior to the render stage), and using the main.
I'd query the whole approach, but mostly because I'm not sure how you're actually differentiating the two databases, or why. Could you provide a bit more information on how you're doing this? I assume the variables you're pulling in dot-points 2 and 5 above are different. I don't need the values, I'm just making sure you've not used the old code duplication and forgotten to edit it (we've all been there).
Note: I'd post this as a comment if I could, but I think the solution may be in how you're pulling the variables. Finally, you could try adding the database name (just the server IP or whatever) to the output, if you're in 'dev'/debug (offline/non-production) mode, to check if it's actually making it to the second server.
For reference, the Django documentation explicitly states you shouldn't do this -- Altering settings at runetime.
There is a lot of talk within the Django community about the ORM supporting multiple connections/databases at once. There's a lot of good reference info out there on it. Check out this blog post: Easy Multi-Database Support for Django and this Django wiki page Multiple Database Support.
In the blog post, Eric Florenzano does something like this in his settings.py file:
DATABASES = dict(
primary = dict(
DATABASE_NAME=DATABASE_NAME,
# ...
),
secondary = dict(
DATABASE_NAME='secondary.db',
# ...
),
)