In Django, is there a way to open any sqlite database file. Make use of the Django ORM, and then close the database. Something like:
def my_view(request):
song1 = Song.objects.get(id=4) # Using normal postgres db
temp_db = open_db('/path/to/my/db.sqlite')
song2 = Song.objects.get(id=4, using=temp_db)
song2.title = song1.title
song2.save()
temp_db.close()
return HttpResponse(temp_db.as_binary(), mime_type='application/x-sqlite3')
In short: my Django web application needs to be able to synchronise with some 3rd party desktop software which stores data in a sqlite database that is stored on the users local computer. The synchronisation only needs to be one way. That is, changes in the web application would update the local sqlite database.
I was thinking I could get away with using the dropbox api to sync the sqlite database. Each user would have their own dropbox database synchronised.
Would it be much easier to do something like this and not use the ORM at all?
conn = sqlite3.connect('/path/to/db.sqlite')
c = conn.cursor()
for row in c.execute('SELECT * FROM Song'):
print row
Related
I have PhpMyAdmin to view and edit a database and a Flask + SQLAlchemy app that uses a table from this database. Everything is working fine and I can read/write to the database from the flask app. However, If I make a change through phpmyadmin, this change is not detected by SQLAlchmey. The only to get those changes is by manually refreshing SQLAlchmey connection
My Question is how to tell SQLAlchemy to reload/refresh its Database connection?
To make sure that the SQLAlchemy engine reads the committed changes to the database, you have to set the isolation level :
engine = create_engine(
"mysql://scott:tiger#localhost/test",
isolation_level="READ UNCOMMITTED"
)
You can read more about isolation levels here and here is the official guide for SQLAlchemy docs (See fist Item)
I suggest you to look at Server Sent Events(SSE). I am looking for code of SSE for postgres,mysql,etc. It is available for reddis.
I have a SQLite database configured with Pyramid Alchemy scaffold in my Linux machine. I have another remote Mysql database which resides in a Windows machine, with loads of data.Now, I have to connect to the remote Mysql database to pull data and populate them into my Sqlite database with the help of sqlAlchemy.
What I had been doing: I used mysql workbench to query data from the mysql database, export results to a csv file, load the csv file into my pyramid initializedb.py through python's default csv module, and then finally insert the retrieved rows into my Sqlite database.
What I want to do: I want to connect to the remote Mysql database from my initializedb.py itself, fetch results and insert them into my sqlite database.
How do I go on about with this? Any help is appreciated.
You can create a connection into your mysql db within the initializedb.py, extract the data and store them into your local db. Now, you will find the basics about sqlalchemy here:
http://docs.sqlalchemy.org/en/rel_0_9/core/tutorial.html
If you need this configurable, then you can put the url of your database into your config and access it through settings.
Also, you do not have to define the structure of your tables exactly, you can use something like:
users = Table('users', metadata, autoload=True)
On the other hand, if your MySQL db structure is the same as the sqlite db structure, it might be possible to reuse your model, but that would probably be hard to explain here without seeing any of your code.
I have a Plone 4 site which uses an additional Postgres database via a Z Psycopg 2 Database Connection object. Since the ZODB is sometimes replicated for testing and development purposes, there are a few fellow database connection objects, in a project_suffix naming scheme; this way, I can select one of the existing database adapters via buildout configuraton script.
However, I noticed that all existing database connection objects are apparently opened when Plone starts up. I don't know whether this is a real problem (e.g. when applying changes to the schema of the database of another instance), but I'd rather have Plone open only the single database which is actually used. How can I achieve this?
(Plone 4.2.4, Postgres 9.1.9, psycopg2 2.5.1, Debian Linux)
Update:
I added some code to the __init__.py of my product, which looks roughly like this:
from Shared.DC.ZRDB.Connection import Connection
...
dbname = env['DATABASE']
db = None
for id, obj in portalfolder.objectItems():
if isinstance(obj, Connection):
if id == dbname:
db = obj
else:
print 'before:', obj._v_connected
obj._v_database_connection.close()
print 'after: ', obj._v_connected
However, this seems not to work; there are no exceptions I'm aware of, but for both before and after, I get a timestamp, and when looking in the ZMI afterwards, the connections seem to be open.
Any ideas, please?
I have an online database and connect to it by using MySQLdb.
db = MySQLdb.connect(......)
cur = db.cursor()
cur.execute("SELECT * FROM YOUR_TABLE_NAME")
data = cur.fetchall()
Now, I want to write the whole database to my localhost (overwrite). Is there any way to do this?
Thanks
If I'm reading you correctly, you have two database servers, A and B (where A is a remote server and B is running on your local machine) and you want to copy a database from server A to server B?
In all honesty, if this is a one-off, consider using the mysqldump command-line tool, either directly or calling it from python.
If not, the last answer on http://bytes.com/topic/python/answers/24635-dump-table-data-mysqldb details the SQL needed to define a procedure to output tables and data, though this may well miss subtleties mysqldump does not
I have an sqlalchemy application that currently uses a local database.The code for the application is given below.
log = core.getLogger()
engine = create_engine('sqlite:///nwtopology.db', echo=False)
Base = declarative_base()
Session = sessionmaker(bind=engine)
session = Session()
class SourcetoPort(Base):
""""""
__tablename__ = 'source_to_port'
id = Column(Integer, primary_key=True)
port_no = Column(Integer)
src_address = Column(String,index=True)
#-----------------------------------------
def __init__(self, src_address,port_no):
""""""
self.src_address = src_address
self.port_no = port_no
I want to create the database itself in a remote machine.I came across this document.
http://www.sqlalchemy.org/doc_pdfs/sqlalchemy_0_6_3.pdf
In the explanation they mentioned the lines given below.
engine = create_engine(’postgresql://scott:tiger#localhost:5432/mydatabase’)
My first question is
1) does sqlite support remote database creation?
2) How do I keep the connection to the remote machine open always? I don't want to initiate an ssh connection every time I have to insert an entry or make a query.
These question may sound stupid but I am very new to python and sqlalchemy.Any help is appreciated.
Answering your questions:
SQLite doesn't support remote database connection - you'll have to implement this by yourself - like putting sqlite database file on shared by network filesystem, but it would make your solution less reliable
My suggestion - do not try to use user remote sqlite database but switch to traditional RDBMS. Please see below for more details.
Sounds like your application had overgrown SQLite. And it is good time to switch to using traditional RDBMS like MySQL or PosgreSQL where network connections are supporting out of the box.
SQLite is local database. SQLite has a page explaining when to use it. It says:
If you have many client programs accessing a common database over a
network, you should consider using a client/server database engine
instead of SQLite.
The good thing is that your application might be database agnostic as you are using SQLAlchemy for generating queries.
So I would do the following:
install database system to machine (it doesn't matter - local or
remote, you can always repeat move your database to remote machine) and configure permissions for your user (create database, alter, select, update and insert)
create database schema and populate data - to clone your existing. There are some tools available for doing so - i.e. Copying Databases across Platforms with SQLAlchemy
sqlite database.
update db connection string in your application from using sqlite to use remote database of your choice
Times have changed.
If one wishes to make a SQLite database available over the web, one option would be to use CubeSQL as a server, and SQLiteManager for SQLite as its client. For details, see e.g. https://www.sqlabs.com/
Another option might be to use Valentina Server similarly: see https://www.valentina-db.com/en/valentina-server-overview
(These options will probably only be suitable if there is at most one client with write-access at a time.)
Are there any others?