[web-devel] [Yesod] Teach me how to write to access

Greg Weber greg at gregweber.info
Tue Mar 1 15:36:00 CET 2011

The default scaffolding site creates a connection pool at startup and stores
it in the foundation type.
You can access the foundation type in your handler with:

  y <- getYesod

Look at the runDB function. It accesses the connection pool from the
foundation type.
Without knowing any more specifics of your situation,
you probably just want to write a function runDB2 that runs against a
different connection pool (to your other database) that you also create at

Greg Weber


> This might not be the correct answer to your problem, but I asked

about how to pass a hashtable to the application in a prevoius mail.

> The answer was to pass the ioref in the data constructor - Michael

wrote a very good example at:


> It might be you can connect to the database, and then pass it on and

handle this second db-connection manually?

> Cheers,

> Petter Egesund

> On Mon, Feb 28, 2011 at 10:05 AM, Katsutoshi Itoh <cutsea110 at gmail.com>
> wrote:

> Hi


> I write an application, which must to access 2 databases.

> 1st is main database for this application.

> 2nd database is used as main database by another application.


> Could you teach me how to write to access 2nd database?

> Since there is no access to the 2nd database only partially, I'm a

> little problem in an ad hoc way.
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