Question

For my project, I need to connect to multiple databases and get information from them. I didn’t think this would be a problem with web2py, but it was. I thought maybe I need to rebuild the db from scratch, but still had problems. Finally, I went through the introductory ‘images’ tutorial and changed it to use an alternate mysql database. I still got the same errors, below is the code:

db.py

db = DAL("mysql://root:@localhost/web2py")
images_db = DAL("mysql://root:@localhost/images_test")


images_db.define_table('image',
   Field('title', unique=True),
   Field('file', 'upload'),
   format = '%(title)s')


images_db.define_table('comment',
   Field('image_id', images_db.image),
   Field('author'),
   Field('email'),
   Field('body', 'text'))

Then I went to the admin page for ‘images’ and clicked the ‘shell’ link under ‘controllers’ and did the following: (after I went to the index page to generate the ‘images’:

Shell:

In [1] : print db(images_db.image).select()
Traceback (most recent call last):
  File "/home/cody/Downloads/web2py/gluon/contrib/shell.py", line 233, in run
    exec compiled in statement_module.__dict__
  File "<string>", line 1, in <module>
  File "/home/cody/Downloads/web2py/gluon/dal.py", line 7577, in select
    fields = adapter.expand_all(fields, adapter.tables(self.query))
  File "/home/cody/Downloads/web2py/gluon/dal.py", line 1172, in expand_all
    for field in self.db[table]:
  File "/home/cody/Downloads/web2py/gluon/dal.py", line 6337, in __getitem__
    return dict.__getitem__(self, str(key))
KeyError: 'image'


In [2] : print images_db.has_key('image')
True


In [3] : print images_db
<DAL {'_migrate_enabled': True, '_lastsql': "SET sql_mode='NO_BACKSLASH_ESCAPES';", '_db_codec': 'UTF-8', '_timings': [('SET FOREIGN_KEY_CHECKS=1;', 0.00017380714416503906), ("SET sql_mode='NO_BACKSLASH_ESCAPES';", 0.00016808509826660156)], '_fake_migrate': False, '_dbname': 'mysql', '_request_tenant': 'request_tenant', '_adapter': <gluon.dal.MySQLAdapter object at 0x2b84750>, '_tables': ['image', 'comment'], '_pending_references': {}, '_fake_migrate_all': False, 'check_reserved': None, '_uri': 'mysql://root:@localhost/images_test', 'comment': <Table {'body': <gluon.dal.Field object at 0x2b844d0>, 'ALL': <gluon.dal.SQLALL object at 0x2b84090>, '_fields': ['id', 'image_id', 'author', 'email', 'body'], '_sequence_name': 'comment_sequence', '_plural': 'Comments', 'author': <gluon.dal.Field object at 0x2b84e10>, '_referenced_by': [], '_format': None, '_db': <DAL {...}>, '_dbt': 'applications/images/databases/e1e448013737cddc822e303fe20f8bec_comment.table', 'email': <gluon.dal.Field object at 0x2b84490>, '_trigger_name': 'comment_sequence', 'image_id': <gluon.dal.Field object at 0x2b84050>, '_actual': True, '_singular': 'Comment', '_tablename': 'comment', '_common_filter': None, 'virtualfields': [], '_id': <gluon.dal.Field object at 0x2b84110>, 'id': <gluon.dal.Field object at 0x2b84110>, '_loggername': 'applications/images/databases/sql.log'}>, 'image': <Table {'ALL': <gluon.dal.SQLALL object at 0x2b84850>, '_fields': ['id', 'title', 'file'], '_sequence_name': 'image_sequence', 'file': <gluon.dal.Field object at 0x2b847d0>, '_plural': 'Images', 'title': <gluon.dal.Field object at 0x2b84610>, '_referenced_by': [('comment', 'image_id')], '_format': '%(title)s', '_db': <DAL {...}>, '_dbt': 'applications/images/databases/e1e448013737cddc822e303fe20f8bec_image.table', '_trigger_name': 'image_sequence', '_loggername': 'applications/images/databases/sql.log', '_actual': True, '_tablename': 'image', '_common_filter': None, 'virtualfields': [], '_id': <gluon.dal.Field object at 0x2b848d0>, 'id': <gluon.dal.Field object at 0x2b848d0>, '_singular': 'Image'}>, '_referee_name': '%(table)s', '_migrate': True, '_pool_size': 0, '_common_fields': [], '_uri_hash': 'e1e448013737cddc822e303fe20f8bec'}>

Now I don’t quite understand why I am getting errors here, everything appears to be in order. I thought web2py supported multiple databases? Am I doing it wrong? The appadmin works fine, perhaps I’ll edit it and get it to raise an error with the code it’s generating… any help would be appreciated.

• Cody

UPDATE:

I just tried this:

MODELS/DB.PY

db = DAL("mysql://root:@localhost/web2py")

images_db = DAL("mysql://root:@localhost/images_test")


images_db.define_table('image',
   Field('title', unique=True),
   Field('file', 'upload'),
   format = '%(title)s')


images_db.define_table('comment',
   Field('image_id', images_db.image),
   Field('author'),
   Field('email'),
   Field('body', 'text'))

CONTROLLERS/DEFAULT.PY

def index():
    """
    example action using the internationalization operator T and flash
    rendered by views/default/index.html or views/generic.html
    """
    if images_db.has_key('image'):
        rows = db(images_db.image).select()
    else:
        rows = 'nope'
    #rows = dir(images_db)
    return dict(rows=rows)

VIEWS/DEFAULT/INDEX.HTML

{{left_sidebar_enabled,right_sidebar_enabled=False,True}}
{{extend 'layout.html'}}


these are the rows:
{{=rows }}

Again, very confused by all of this. Appreciate any help.

Answer 1

If you want to query the images_db connection, you have to call images_db(), not db(). So, it would be:

images_db(images_db.image).select()