Re: [web2py] Re: Modules: how to access db
Thanks for that! I've never tested it in a multi-threaded environment. On Sat, Feb 11, 2012 at 4:41 AM, nick name wrote: > This solution will lead to a race condition. Do not use it! > > If you have multiple threads, they might update your commons at the same > time and you'll get request from one session, and session from another, and > db from a third. > > "current" is a thread-local thing, guaranteed not to be touched by any > other part - use "current", not "common" (or whatever your own module is > called) > -- Sathvik Ponangi
Re: [web2py] Re: Modules: how to access db
other ways to do it without using current. in the module (ex. tools.py): def regte_verwysing(regte, tabel, veld, db): lys = db(db[tabel].article == regte).select(db[tabel][veld]) verwysings = [x[veld] for x in lys] return verwysings in the model (ex. db.py): import tools.py def regte_verwysing(regte, tabel, veld): return tools.regte_verwysing(regte, tabel, veld, db) If you like closures. in the module (ex. tools.py): def regte_verwysing(db): def f(regte, tabel, veld): lys = db(db[tabel].article == regte).select(db[tabel][veld]) verwysings = [x[veld] for x in lys] return verwysings return f in the model (ex. db.py): import tools.py regte_verwysing = tools.regte_verwysing(db) #<- returns a callable with args (regte, tabel, veld) you can then call regte_verwysing(regte, tabel, veld) in your code mic 2012/2/10 Johann Spies : > On 9 February 2012 18:14, Bruno Rocha wrote: >> >> I dont know exactly how it works, but I had problems serializing db in to >> current, so Massimo said to always pass it explicitly to classes ad >> functions, I remember that SQLITE worked, but not Postgres. > > > Anthony's advice to me earlier in this thread is working with PostgreSQL: > > In db.py: > > > from gluon import current > current.db = db > > and in the module: > > from gluon import * > def regte_verwysing(regte, tabel, veld): > db = current.db > lys = db(db[tabel].article == regte).select(db[tabel][veld]) > verwysings = [x[veld] for x in lys] > return verwysings > > Regards > Johann > -- > Because experiencing your loyal love is better than life itself, > my lips will praise you. (Psalm 63:3) >
Re: [web2py] Re: Modules: how to access db
On 9 February 2012 18:14, Bruno Rocha wrote: > I dont know exactly how it works, but I had problems serializing db in to > current, so Massimo said to always pass it explicitly to classes ad > functions, I remember that SQLITE worked, but not Postgres. Anthony's advice to me earlier in this thread is working with PostgreSQL: In db.py: from gluon import current current.db = db and in the module: from gluon import * def regte_verwysing(regte, tabel, veld): db = current.db lys = db(db[tabel].article == regte).select(db[tabel][veld]) verwysings = [x[veld] for x in lys] return verwysings Regards Johann -- Because experiencing your loyal love is better than life itself, my lips will praise you. (Psalm 63:3)
Re: [web2py] Re: Modules: how to access db
I dont know exactly how it works, but I had problems serializing db in to current, so Massimo said to always pass it explicitly to classes ad functions, I remember that SQLITE worked, but not Postgres. -- Bruno Rocha [http://rochacbruno.com.br]
Re: [web2py] Re: Modules: how to access db
Now that is a lot nicer then passing in the db to every module class. Does this only work with trunk? Or the latest stable release? On Thu, Feb 9, 2012 at 7:30 AM, omicron wrote: > With the last version, you can do this : > > from gluon import current > > dba = current.globalenv['db'] > > -- -- Regards, Bruce Wade http://ca.linkedin.com/in/brucelwade http://www.wadecybertech.com http://www.warplydesigned.com http://www.fitnessfriendsfinder.com
Re: [web2py] Re: Modules: how to access db
On Thu, Feb 9, 2012 at 11:45 AM, Anthony wrote: > from gluon import current > current.db = db > I dont think that adding db to current will work properly, it can work in SQLITE, but for sure will raise problems with another databases. I realized that db needs to be instantiated inside a module or passed explicitly as an arg, it is not possible to serialize it in to current. It works in the first request, but not for the subsequents. Another advice is that you never have to assign variables to current outside functions and methods Example. *Module.py* from gluon import current > request = current.request > > def myfunction(db): > if request.args... # HERE BE THE DRAGONS! > To work you need to do *Module.py* from gluon import current def myfunction(db): request = current.request if request.args # IT WORKS It happens because if you assign outside the function, it will be evaluated only at the first request, and for the subsequents, the request object will always be the same. -- Bruno Rocha [http://rochacbruno.com.br]
Re: [web2py] Re: Modules: how to access db
On 9 February 2012 15:45, Anthony wrote: > I do not understand this properly. >> >> After explicitly importing 'current' in the controller, I made some >> progress. But why is the class definition necessary and how does it >> initialise db when db is not available in the module? >> > > You don't necessarily need a class. The point is just that you need to > pass in the db instance, either via an __init__ method of a class, or > simply as an argument to your function. In your case: > > def number_of_records(db, table): > > And when you call that function, pass in your db object as the first > argument. Another option is to add the db object to "current" -- for > example, in the db.py model file: > > from gluon import current > current.db = db > > Then when you import current in your module, you can refer to current.db. > > Thanks Anthony. That clears up a few things for me. Regards Johann -- Because experiencing your loyal love is better than life itself, my lips will praise you. (Psalm 63:3)
Re: [web2py] Re: Modules: how to access db
> > I do not understand this properly. > > After explicitly importing 'current' in the controller, I made some > progress. But why is the class definition necessary and how does it > initialise db when db is not available in the module? > You don't necessarily need a class. The point is just that you need to pass in the db instance, either via an __init__ method of a class, or simply as an argument to your function. In your case: def number_of_records(db, table): And when you call that function, pass in your db object as the first argument. Another option is to add the db object to "current" -- for example, in the db.py model file: from gluon import current current.db = db Then when you import current in your module, you can refer to current.db. Anthony
Re: [web2py] Re: Modules: how to access db
Thanks Ross. On 9 February 2012 14:39, Ross Peoples wrote: > from gluon import * > > This should give you the "current" object which has these: > > current.request > current.response > current.cache > > You must initialize your modules with a db instance though. So I usually > do this: > > class MyModule(object): > def __init__(self, db, ...) > I do not understand this properly. After explicitly importing 'current' in the controller, I made some progress. But why is the class definition necessary and how does it initialise db when db is not available in the module? Regards Johann -- Because experiencing your loyal love is better than life itself, my lips will praise you. (Psalm 63:3)
