my mistake, the alias should be for table location.
location_one = db.location.with_alias('location_one')
location_two = db.location.with_alias('location_two')
I hope this works.
Am Dienstag, 27. August 2013 21:51:56 UTC+2 schrieb Apple Mason:
>
> Hey Alex,
>
> Thanks for the suggestion. The problem with the query is that
> 'location_one.geom.st_equals(point_x_y)' won't work. That's because the
> table db.item_location doesn't have a field called 'geom'. This is the
> error:
>
> AttributeError: 'Table' object has no attribute 'geom'
>
>
> Is there a way to implicitly reference the fields in another table so that
> it will work?
>
> On Tuesday, August 27, 2013 3:15:10 PM UTC-4, Alex wrote:
>>
>> try something like this:
>>
>>
>> location_one = db.item_location.with_alias('location_one')
>> location_two = db.item_location.with_alias('location_two')
>> rows = db((db.item_location.item == db.item.id) & (db.item.id != itemid)
>> & (db.item_location.location_one == location_one.id) &
>> (db.item_location.location_two
>> == location_two.id) &
>> (location_one.geom.st_equals(point_x_y)) & (location_two.geom.
>> st_equals(point_n_m))).select(db.item.ALL)
>>
>> Alex
>>
>> Am Dienstag, 27. August 2013 19:43:08 UTC+2 schrieb Apple Mason:
>>>
>>> I have this many to many relationship example:
>>>
>>> db.define_table('location',
>>> Field('geom', 'geometry()'))
>>>
>>> db.define_table('item',
>>> Field('name'))
>>>
>>> db.define_table('item_location',
>>> Field('item', db.item),
>>> Field('location_one', db.location),
>>> Field('location_two', db.location))
>>>
>>>
>>>
>>> The goal is to find all items that are NOT the given item.id, but
>>> matches locations.
>>> An example query would be:
>>>
>>> Given: item.id==1 and two points POINT(x,y) and POINT(n,m),
>>> Result: "get all items that are not item.id==1, but has
>>> location_one==POINT(x,y) and location_two==POINT(n,m)"
>>>
>>> I am able to get it matching one of the points, but not the other with
>>> this:
>>>
>>>
>>> point_x_y = "POINT(1,2)"
>>> point_n_m = "POINT(3,4)"
>>> itemid = 1
>>>
>>> t = db( (db.item.id==db.item_location.item) &
>>> ( (db.location.id==db.item_location.location_one) & (db.
>>> location.geom.st_equals(point_x_y))))
>>>
>>> result = t( db.item.id != itemid ).select()
>>>
>>>
>>> This will successfully match all items that do not have an id=1, and has
>>> location_one as point_x_y.
>>>
>>> The problem is I do not know how to match location_two with point_n_m. I
>>> tried this, but it doesn't make sense (it also returns in nothing):
>>>
>>> t = db( (db.item.id==db.item_location.item) &
>>> ( (db.location.id==db.item_location.location_one) & (db.
>>> location.geom.st_equals(point_x_y)))
>>> ( (db.location.id==db.item_location.location_two) & (db.
>>> location.geom.st_equals(point_n_m))))
>>>
>>> Any help would be great!
>>>
>>
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