Connection with third database using multidb implementing DB Router

[Ovnicraft]

Hi to all friends !

 

I am working in django project its has many apps with their default db configured.

So now i need to read (and possible write) to third DB (mysql) and i found a thread[1] here about it.

There are some suggestions about write ReadOnly objects, redefine save methods but i'm not totally convinced about it.

Reading documentation about multidb i found DB routes and it has allow_syndb[2] so my question is, if i code to dont allow sync any model in third db i can query (RAW SQL) without problems ? 

I dont want to write any dirty layer to connect to my third DB just re-use django engine.

I will appreciated your help !

Best regards, 

[1] https://groups.google.com/forum/#!msg/django-users/rv6D5Pqs7Fo/pkwinU7PGOQJ

[2] https://docs.djangoproject.com/en/1.4/topics/db/multi-db/#allow_syncdb

--
Cristian Salamea
@ovnicraft

[George Silva]

I only had to query external databases.

I've created my models as managed=False and implemented a custom manager that redefined the default database configuration. We did not had situations where depending on a certain condition the target database would change, but this worked just fine.

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George R. C. Silva
SIGMA Consultoria

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http://www.consultoriasigma.com.br/

[Ovnicraft]

On Fri, Nov 8, 2013 at 11:39 AM, George Silva <george...@gmail.com> wrote:

I only had to query external databases.

I've created my models as managed=False and implemented a custom manager that redefined the default database configuration. We did not had situations where depending on a certain condition the target database would change, but this worked just fine.

What database configuration did you change ?

Regards, 

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Cristian Salamea
@ovnicraft

[George Silva]

Let me explain this better.

I've created a custom manager, in which I replaced the default database alias it should connect.

class ExternalManager(models.Manager):

    """

    Manager customizado para buscar os dados no banco legado.

    """

    alias = None




    def __init__(self, alias=None):

        self.alias = alias

        super(LegadoManager, self).__init__()




    def get_query_set(self):

        """

        Retorna um query set conectando ao banco legado.

        """

        if not hasattr(self.model, '_db_alias'):

            self.model._db_alias = self.alias

        qs = QuerySet(self.model)

        if self.model._db_alias is not None:

            qs = qs.using(self.model._db_alias)

        return qs






Now, create your model and override the objects property, passing the name of the database configured in settings.py as the alias.

Like this:

class ModelInAnotherDatabase(models.Model):

    name = models.CharField()

    objects = ExternalManager(alias="external")

Where external is the database name configured in settings.py.

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[Ovnicraft]

I will check it ! thanks ! 

To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAGyPVTsDVY89bjLP2nkEDQ14vJ8K7xG21riFGj70b2HROm731w%40mail.gmail.com.

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Cristian Salamea
@ovnicraft