[sqlalchemy] round robin implementation issue
Hello guys,
I am implementing a round robin database for my project in SQLAlchemy and I
have some problems with TRIGGERS.
Everything works but for each INSERT OR REPLACE, the trigger is not called
at all so in this case I would have only 25 rows rather than 50.
Any suggestion to debug it?
Here's my code:
def InitRoundRobin(self):
Creates all the tables necessary one for the network swap
events and one for the motion
#print Creating database +self.__file_path
self.__file_event = Table('network', self.__metadata,
Column('rrd_key', Integer, Sequence('rrd_key_seq'),
primary_key=True),
Column('name', String, default=NONE),
Column('location', String, default=NONE),
Column('type', String,default=NUM),
Column('direction', String,default=INP),
Column('value', String,default=0),
Column('time', TIMESTAMP(), default=now()),
UniqueConstraint('name', 'time', name='name_time')
)
self.__file_event.create()
self.__file_rrd = Table('rrdkey', self.__metadata,
Column('rrd_key', Integer, Sequence('rrd_key_seq'),
primary_key=True)
)
self.__file_rrd.create()
operation = self.__file_rrd.insert()
## attempt an insert
result=operation.execute(rrd_key=0);
self.rrd_ins = DDL('''\
DROP TRIGGER IF EXISTS rrd_ins;
DELIMITER $$
CREATE TRIGGER rrd_ins
BEFORE INSERT ON network
FOR EACH ROW
BEGIN
SET @rrd_key = 0;
SET @rows = 10;
IF NEW.rrd_key = 0 THEN
SELECT rrd_key + 1
FROM rrdkey
INTO @rrd_key;
SET NEW.rrd_key = @rrd_key;
END IF;
IF (NEW.rrd_key % @rows) THEN
SET NEW.rrd_key = NEW.rrd_key % @rows;
ELSE
SET NEW.rrd_key = @rows;
END IF;
UPDATE network SET rrd_key = NEW.rrd_key;
END;
$$
DELIMITER;''')
event.listen(self.__file_event, 'after_create', self.rrd_ins)
And the REPLACE code:
def addEntryReplace(self, location,name,value,type):
#print Adding entry
#operation = self.__file_event.insert()
t = text(INSERT OR REPLACE INTO network
(location,name,value,type,time) VALUES
(:location,:name,:value,:type,:time))
print t
#operation.prefix_with(OR REPLACE);
result=self.__connection.execute(t, location=location,
name=name, value=value, type=type, time=now())
This is called like this:
def loopTest(self):
self.__connection=connection = self.__db.connect()
for i in range(0, 50):
self.addEntryReplace(CASA,PARAM,i,TYPE)
print Added entry , i
self.__connection.close()
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[sqlalchemy] SQLite rollback() fails
Hi, I've run into a rather interesting issue, where calling session.rollback() dies. The error I get with SQLA 0.7 is: class 'sqlalchemy.exc.InvalidRequestError': Can't attach instance Foo at 0x2acf68808710; another instance with key (class 'module.Foo', (342,)) is already present in this session. Traceback: sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:672:rollback sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:386:rollback sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:417:_rollback_impl sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:274:_restore_snapshot sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:1620:_update_impl sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:1648:_attach 0.8 gives a slightly different message, but I think it is essentially the same: type 'exceptions.AssertionError': A conflicting state is already present in the identity map for key (class 'module.Foo', (342,)) Traceback: sqlalchemy-default/lib/sqlalchemy/orm/session.py:637:rollback sqlalchemy-default/lib/sqlalchemy/orm/session.py:346:rollback sqlalchemy-default/lib/sqlalchemy/orm/session.py:377:_rollback_impl sqlalchemy-default/lib/sqlalchemy/orm/session.py:233:_restore_snapshot sqlalchemy-default/lib/sqlalchemy/orm/session.py:1578:_update_impl sqlalchemy-default/lib/sqlalchemy/orm/identity.py:115:add What I see when turning on query logging: - The Foo object with primary key 342 is loaded (using a non-primary mapper, if that makes any difference), and then deleted. The session is flushed. - A new object is created (this time using the primary mapper), and during INSERT, SQLite assigns the same primary key to it as the previously deleted object had (I can see that from subsequent SELECT statements referencing the new object; it would be nice if SQLA logged the primary key after an INSERT at debug level) - An application error (unrelated to SQLAlchemy) occurs, which causes rollback() to be called I have a reliable reproducer, but it is the unit test of a large application, so there are lots of possibly unrelated things going on. I've spent two days coming up with a standalone reproducer, but I've failed, that's why I'm sending this mail instead of opening a ticket. Any ideas? Gabor -- NOTICE: Morgan Stanley is not acting as a municipal advisor and the opinions or views contained herein are not intended to be, and do not constitute, advice within the meaning of Section 975 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. If you have received this communication in error, please destroy all electronic and paper copies and notify the sender immediately. Mistransmission is not intended to waive confidentiality or privilege. Morgan Stanley reserves the right, to the extent permitted under applicable law, to monitor electronic communications. This message is subject to terms available at the following link: http://www.morganstanley.com/disclaimers. If you cannot access these links, please notify us by reply message and we will send the contents to you. By messaging with Morgan Stanley you consent to the foregoing. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
RE: [sqlalchemy] SQLite rollback() fails
I've tested the 0.7 0.8 snapshots, and both work fine now. Thanks! From: sqlalchemy@googlegroups.com [mailto:sqlalchemy@googlegroups.com] On Behalf Of Michael Bayer Sent: 03 October 2012 17:20 To: sqlalchemy@googlegroups.com Subject: Re: [sqlalchemy] SQLite rollback() fails On Oct 3, 2012, at 10:34 AM, Michael Bayer wrote: Catching both of these is easy enough and a patch is added to #2583: http://www.sqlalchemy.org/trac/ticket/2583 The SQLite case you describe isn't exactly like either of these; if the object were flushed by the session and received the same PK, that case is already handled since the object would be in ._new. So my only guess is that, that's not the trigger of the issue.So at the very least you need to try that patch and see if it clears things up. Assuming that's the fix, I don't know that there's a clean way to patch this in, except for patching your install or monkeypatching a new Session class in. I should have it committed in both 0.7/0.8 within 30, unless I hit some snags in the tests. OK those are in tip for default + 0.7, so you can get those fixes now from the snapshot releases. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.commailto:sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.commailto:sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- NOTICE: Morgan Stanley is not acting as a municipal advisor and the opinions or views contained herein are not intended to be, and do not constitute, advice within the meaning of Section 975 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. If you have received this communication in error, please destroy all electronic and paper copies and notify the sender immediately. Mistransmission is not intended to waive confidentiality or privilege. Morgan Stanley reserves the right, to the extent permitted under applicable law, to monitor electronic communications. This message is subject to terms available at the following link: http://www.morganstanley.com/disclaimers. If you cannot access these links, please notify us by reply message and we will send the contents to you. By messaging with Morgan Stanley you consent to the foregoing. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] SQLALCHEMY query.
Hi- I have a sql query which is returning 2 rows. But when is transformed to ORM query, its not returning any rows. My SQL Statement: select distinct(inst.hostname) as server_name, fip.address as fixed_ip_address, vif.address as fixed_ip_mac_address from instances inst, instance_metadata mtd, virtual_interfaces vif, fixed_ips fip where inst.id = mtd.instance_id and mtd.instance_id = vif.instance_id and vif.instance_id = fip.instance_id and inst.project_id = 'e216fcb54dc944a8ab16e4e325299643' and mtd.key = 'Server Group' and mtd.value = 'DOM1' group by mtd.key,mtd.value; SQL +-+--+--+ | server_name | fixed_ip_address | fixed_ip_mac_address | +-+--+--+ | serverpoc | 172.15.1.2 | fa:16:3e:56:47:71| | serverpoc2 | 172.15.1.3 | fa:16:3e:4f:3c:9b| +-+--+--+ I have written the ORM query as result = session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\ join((models.InstanceMetadata, models.InstanceMetadata.instance_id == models.Instance.id http://models.instance.id/)).\ join ((models.FixedIp, models.FixedIp.instance_id == models.InstanceMetadata.instance_id)).\ join ((models.VirtualInterface, models.VirtualInterface.instance_id == models.FixedIp.instance_id)).\ filter(and_(models.Instance.project_id == search_opts['project_id'])).\ filter(and_(models.InstanceMetadata.key == str(search_opts['key']) )).\ filter(and_(models.InstanceMetadata.value == str(search_opts['value']))).\ all() Can any one help me find the fault in the ORM query. Thanks in advance. - Trinath -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To view this discussion on the web visit https://groups.google.com/d/msg/sqlalchemy/-/a-nPCWf-HTEJ. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] SQLALCHEMY query.
On Wed, Oct 3, 2012 at 5:02 PM, Trinath Somanchi trinath.soman...@gmail.com wrote: Hi- I have a sql query which is returning 2 rows. But when is transformed to ORM query, its not returning any rows. My SQL Statement: select distinct(inst.hostname) as server_name, fip.address as fixed_ip_address, vif.address as fixed_ip_mac_address from instances inst, instance_metadata mtd, virtual_interfaces vif, fixed_ips fip where inst.id = mtd.instance_id and mtd.instance_id = vif.instance_id and vif.instance_id = fip.instance_id and inst.project_id = 'e216fcb54dc944a8ab16e4e325299643' and mtd.key = 'Server Group' and mtd.value = 'DOM1' group by mtd.key,mtd.value; SQL +-+--+--+ | server_name | fixed_ip_address | fixed_ip_mac_address | +-+--+--+ | serverpoc | 172.15.1.2 | fa:16:3e:56:47:71| | serverpoc2 | 172.15.1.3 | fa:16:3e:4f:3c:9b| +-+--+--+ I have written the ORM query as result = session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\ join((models.InstanceMetadata, models.InstanceMetadata.instance_id == models.Instance.id)).\ join ((models.FixedIp, models.FixedIp.instance_id == models.InstanceMetadata.instance_id)).\ join ((models.VirtualInterface, models.VirtualInterface.instance_id == models.FixedIp.instance_id)).\ filter(and_(models.Instance.project_id == search_opts['project_id'])).\ filter(and_(models.InstanceMetadata.key == str(search_opts['key']) )).\ filter(and_(models.InstanceMetadata.value == str(search_opts['value']))).\ all() Can any one help me find the fault in the ORM query. Thanks in advance. Have you tried turning on SQL logging (eg. by passing echo=True to create_engine), and comparing the query with your original? If the query looks ok, maybe the parameters you are passing aren't exactly what you think they should be. (Also, I'm not sure if it makes any difference, but those and_() calls inside filter() are unnecessary - filtering a query already implies that you are AND-ing the condition with all the previous conditions) Simon -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] SQLALCHEMY query.
Hi Simon-
I have update my ORM query this way
result =
session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\
join((models.InstanceMetadata,
models.InstanceMetadata.instance_id ==
models.Instance.id)).\
join ((models.FixedIp,
models.FixedIp.instance_id ==
models.InstanceMetadata.instance_id)).\
join ((models.VirtualInterface,
models.VirtualInterface.instance_id ==
models.FixedIp.instance_id)).\
filter(and_(models.Instance.project_id == search_opts['project_id'],
models.InstanceMetadata.key ==
search_opts['key'],
models.InstanceMetadata.value ==
search_opts['value'])).\
all()
I have received an Programming error
ProgrammingError: (ProgrammingError) (1064, 'You have an error in your SQL
syntax; check the manual that corresponds to your MySQL server version for
the right syntax to use near \') AND instance_metadata.value =
(\'DOM1\',)\' at line 3') 'SELECT DISTINCT instances.hostname AS anon_1,
fixed_ips.address AS fixed_ips_address, virtual_interfaces.address AS
virtual_interfaces_address \nFROM instances INNER JOIN instance_metadata ON
instance_metadata.instance_id = instances.id INNER JOIN fixed_ips ON
fixed_ips.instance_id = instance_metadata.instance_id INNER JOIN
virtual_interfaces ON virtual_interfaces.instance_id =
fixed_ips.instance_id \nWHERE instances.project_id = %s AND
instance_metadata.`key` = %s AND instance_metadata.value = %s'
('e216fcb54dc944a8ab16e4e325299643', ['Server Group'], ['DOM1'])
Can you help me troubleshoot the issue.
Thanks a lot for the reply.
-
Trinath
On Wednesday, 3 October 2012 21:47:23 UTC+5:30, Simon King wrote:
On Wed, Oct 3, 2012 at 5:02 PM, Trinath Somanchi
trinath@gmail.com javascript: wrote:
Hi-
I have a sql query which is returning 2 rows. But when is transformed to
ORM
query, its not returning any rows.
My SQL Statement:
select distinct(inst.hostname) as server_name,
fip.address as fixed_ip_address,
vif.address as fixed_ip_mac_address
from instances inst, instance_metadata mtd, virtual_interfaces vif,
fixed_ips fip
where inst.id = mtd.instance_id and
mtd.instance_id = vif.instance_id and
vif.instance_id = fip.instance_id and
inst.project_id = 'e216fcb54dc944a8ab16e4e325299643' and
mtd.key = 'Server Group' and
mtd.value = 'DOM1'
group by mtd.key,mtd.value;
SQL
+-+--+--+
| server_name | fixed_ip_address | fixed_ip_mac_address |
+-+--+--+
| serverpoc | 172.15.1.2 | fa:16:3e:56:47:71|
| serverpoc2 | 172.15.1.3 | fa:16:3e:4f:3c:9b|
+-+--+--+
I have written the ORM query as
result =
session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\
join((models.InstanceMetadata,
models.InstanceMetadata.instance_id ==
models.Instance.id)).\
join ((models.FixedIp,
models.FixedIp.instance_id ==
models.InstanceMetadata.instance_id)).\
join ((models.VirtualInterface,
models.VirtualInterface.instance_id ==
models.FixedIp.instance_id)).\
filter(and_(models.Instance.project_id ==
search_opts['project_id'])).\
filter(and_(models.InstanceMetadata.key ==
str(search_opts['key']) )).\
filter(and_(models.InstanceMetadata.value ==
str(search_opts['value']))).\
all()
Can any one help me find the fault in the ORM query.
Thanks in advance.
Have you tried turning on SQL logging (eg. by passing echo=True to
create_engine), and comparing the query with your original? If the
query looks ok, maybe the parameters you are passing aren't exactly
what you think they should be.
(Also, I'm not sure if it makes any difference, but those and_()
calls inside filter() are unnecessary - filtering a query already
implies that you are AND-ing the condition with all the previous
conditions)
Simon
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Re: [sqlalchemy] SQLALCHEMY query.
On Wed, Oct 3, 2012 at 5:23 PM, Trinath Somanchi
trinath.soman...@gmail.com wrote:
Hi Simon-
I have update my ORM query this way
result =
session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\
join((models.InstanceMetadata,
models.InstanceMetadata.instance_id ==
models.Instance.id)).\
join ((models.FixedIp,
models.FixedIp.instance_id ==
models.InstanceMetadata.instance_id)).\
join ((models.VirtualInterface,
models.VirtualInterface.instance_id ==
models.FixedIp.instance_id)).\
filter(and_(models.Instance.project_id == search_opts['project_id'],
models.InstanceMetadata.key ==
search_opts['key'],
models.InstanceMetadata.value ==
search_opts['value'])).\
all()
I have received an Programming error
ProgrammingError: (ProgrammingError) (1064, 'You have an error in your SQL
syntax; check the manual that corresponds to your MySQL server version for
the right syntax to use near \') AND instance_metadata.value =
(\'DOM1\',)\' at line 3') 'SELECT DISTINCT instances.hostname AS anon_1,
fixed_ips.address AS fixed_ips_address, virtual_interfaces.address AS
virtual_interfaces_address \nFROM instances INNER JOIN instance_metadata ON
instance_metadata.instance_id = instances.id INNER JOIN fixed_ips ON
fixed_ips.instance_id = instance_metadata.instance_id INNER JOIN
virtual_interfaces ON virtual_interfaces.instance_id = fixed_ips.instance_id
\nWHERE instances.project_id = %s AND instance_metadata.`key` = %s AND
instance_metadata.value = %s' ('e216fcb54dc944a8ab16e4e325299643', ['Server
Group'], ['DOM1'])
Can you help me troubleshoot the issue.
The parameters you are passing to the query are:
('e216fcb54dc944a8ab16e4e325299643', ['Server Group'], ['DOM1'])
but I suspect they should be
('e216fcb54dc944a8ab16e4e325299643', 'Server Group', 'DOM1')
ie. the last 2 elements should be strings, not single-element lists.
If you are getting these from a web form, are they perhaps
multiple-selection fields? In which case you'll probably want to
change the search conditions to be something like:
models.InstanceMetadata.key.in_(search_opts['key'])
However, you should only add that condition if search_opts['key'] is
not empty. (I *think* SA warns you if you pass an empty list to in_)
Simon
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Re: [sqlalchemy] SQLALCHEMY query.
Hi-
I have solved the issue mysql.
Just converted the LIST to string for key and value..
and the query is working fine.
Thanks a lot guys for the help..
Thanks a lot Simon...for the precious help./
-
Trinath
On Wednesday, 3 October 2012 21:53:05 UTC+5:30, Trinath Somanchi wrote:
Hi Simon-
I have update my ORM query this way
result =
session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\
join((models.InstanceMetadata,
models.InstanceMetadata.instance_id ==
models.Instance.id)).\
join ((models.FixedIp,
models.FixedIp.instance_id ==
models.InstanceMetadata.instance_id)).\
join ((models.VirtualInterface,
models.VirtualInterface.instance_id ==
models.FixedIp.instance_id)).\
filter(and_(models.Instance.project_id == search_opts['project_id'],
models.InstanceMetadata.key ==
search_opts['key'],
models.InstanceMetadata.value ==
search_opts['value'])).\
all()
I have received an Programming error
ProgrammingError: (ProgrammingError) (1064, 'You have an error in your SQL
syntax; check the manual that corresponds to your MySQL server version for
the right syntax to use near \') AND instance_metadata.value =
(\'DOM1\',)\' at line 3') 'SELECT DISTINCT instances.hostname AS anon_1,
fixed_ips.address AS fixed_ips_address, virtual_interfaces.address AS
virtual_interfaces_address \nFROM instances INNER JOIN instance_metadata ON
instance_metadata.instance_id = instances.id INNER JOIN fixed_ips ON
fixed_ips.instance_id = instance_metadata.instance_id INNER JOIN
virtual_interfaces ON virtual_interfaces.instance_id =
fixed_ips.instance_id \nWHERE instances.project_id = %s AND
instance_metadata.`key` = %s AND instance_metadata.value = %s'
('e216fcb54dc944a8ab16e4e325299643', ['Server Group'], ['DOM1'])
Can you help me troubleshoot the issue.
Thanks a lot for the reply.
-
Trinath
On Wednesday, 3 October 2012 21:47:23 UTC+5:30, Simon King wrote:
On Wed, Oct 3, 2012 at 5:02 PM, Trinath Somanchi
trinath@gmail.com wrote:
Hi-
I have a sql query which is returning 2 rows. But when is transformed
to ORM
query, its not returning any rows.
My SQL Statement:
select distinct(inst.hostname) as server_name,
fip.address as fixed_ip_address,
vif.address as fixed_ip_mac_address
from instances inst, instance_metadata mtd, virtual_interfaces vif,
fixed_ips fip
where inst.id = mtd.instance_id and
mtd.instance_id = vif.instance_id and
vif.instance_id = fip.instance_id and
inst.project_id = 'e216fcb54dc944a8ab16e4e325299643' and
mtd.key = 'Server Group' and
mtd.value = 'DOM1'
group by mtd.key,mtd.value;
SQL
+-+--+--+
| server_name | fixed_ip_address | fixed_ip_mac_address |
+-+--+--+
| serverpoc | 172.15.1.2 | fa:16:3e:56:47:71|
| serverpoc2 | 172.15.1.3 | fa:16:3e:4f:3c:9b|
+-+--+--+
I have written the ORM query as
result =
session.query(models.Instance.hostname.distinct(),models.FixedIp.address,models.VirtualInterface.address).\
join((models.InstanceMetadata,
models.InstanceMetadata.instance_id ==
models.Instance.id)).\
join ((models.FixedIp,
models.FixedIp.instance_id ==
models.InstanceMetadata.instance_id)).\
join ((models.VirtualInterface,
models.VirtualInterface.instance_id ==
models.FixedIp.instance_id)).\
filter(and_(models.Instance.project_id ==
search_opts['project_id'])).\
filter(and_(models.InstanceMetadata.key ==
str(search_opts['key']) )).\
filter(and_(models.InstanceMetadata.value ==
str(search_opts['value']))).\
all()
Can any one help me find the fault in the ORM query.
Thanks in advance.
Have you tried turning on SQL logging (eg. by passing echo=True to
create_engine), and comparing the query with your original? If the
query looks ok, maybe the parameters you are passing aren't exactly
what you think they should be.
(Also, I'm not sure if it makes any difference, but those and_()
calls inside filter() are unnecessary - filtering a query already
implies that you are AND-ing the condition with all the previous
conditions)
Simon
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RE: [sqlalchemy] live access to postgis database to use in ExtJS, OpenLayers, etc
thanks a lot for the answer, I didn't expect that, nice from you. I'll take a look at that and see what I keep doing, in fact I have set all the backend and client part, the only thing I need is to leave the door open to my pg tables, so I can (at first) search inside them and plot the features in OL. Through the postgis_geojson.php script and extjs I'm trying that because it allows what I need, it's just to find a way to pass the two variables I need and overwrite the default ext-comp104 of the xtype. But yes, this is beyond the scope of this forum. BTW my question (live access to postgis database) was related to what the MapFish guys did in the MapFish demo (great project btw, these guys are geniuses), they just use an url to do the search function, I know there is bunch of things behind (Pylons, etc), but I just wanted to know if it's possible to do it easier than that, perhaps with just SqlAlchemy, but I think a RESTful framework could work also. Many thanks also Michael for your email, helpful as always. Cheers, Gery __ Piensa en el medio ambiente - mantenlo en la pantalla. NO lo imprimas si NO es necesario. Think green - keep it on the screen. Do NOT print if it is NOT necessary. Denken Sie an die Umwelt - bewahren Sie es auf dem Bildschirm. Drucken Sie NICHT, wenn es NICHT notwendig ist. From: si...@simonking.org.uk Date: Wed, 3 Oct 2012 10:18:47 +0100 Subject: Re: [sqlalchemy] live access to postgis database to use in ExtJS, OpenLayers, etc To: sqlalchemy@googlegroups.com On Tue, Oct 2, 2012 at 7:26 PM, Gery . gameji...@hotmail.com wrote: thanks for the email, it seems that you know a lot about this stuff, it'd be great if you could share what you know so in that way we will learn from you, but as expected you won't do it, your Sorry I can't be more help, is very clear as always. But hey anyway, I appreciate that you demostrate how you really are. I was just trying to demonstrate that what you are trying to do is complicated, with a lot of interactions between different technologies. You need to break it down into smaller tasks that you can test, and get each piece working before starting on the next. I recommend that you start by taking the example GeoJSON file from http://www.geojson.org/geojson-spec.html#examples and saving that on your web server. Change your javascript to load that file, and check that you can actually see the data from the file in your application. If you can't get this working you'll need to talk to someone who knows about OpenLayers (I don't know anything about it) Once you've done that, put a python script in the cgi-bin directory of your web server that looks something like this: -- #!/usr/bin/env python # CGI scripts start by sending the HTTP headers. The only # one you absolutely need is the Content-type header. # I'm not sure if OpenLayers requires a specific content type # so you may need to experiment here. print Content-type: application/json # In HTTP, a blank line separates the headers from the body # of the response print # Anything else that you print forms the body of the response. # In this case, we just want to send the example GeoJSON data. print include the example GeoJSON file here -- Visit http://localhost/cgi-bin/yourscript.py in your web browser and verify that you see the GeoJSON data. If that doesn't work, you'll probably need to contact the Python mailing list. Update your Javascript to point to that URL. You should still be able to see the data within your application. Once you've got all that working, you can start adding SQLAlchemy into the python script. Let us know when you get there and we might be able to help. Simon -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] live access to postgis database to use in ExtJS, OpenLayers, etc
It sounds like you are trying to do at least 6 quite complicated things all at once, without really understanding any of them. This will not be easy. Sigh. The story of my life in one sentence. On Tue, Oct 2, 2012 at 8:43 AM, Simon King si...@simonking.org.uk wrote: On Mon, Oct 1, 2012 at 11:38 PM, Gery . gameji...@hotmail.com wrote: thanks but I want to use that live access to search at first through ExtJS/GeoExtJS/OpenLayers and through them there is only a url available (protocol HTTP), I also need to get the data as GeoJSON, so I think GeoAlchemy might not be the right solution, I think. If I'm wrong, please I'd love some points about it, thanks. It sounds like you are trying to do at least 6 quite complicated things all at once, without really understanding any of them. This will not be easy. 1. The client side of your application is presumably written in Javascript and HTML, using javascript libraries such as ExtJS and OpenLayers. You need to fully understand how these work. 2. The application will then make HTTP requests to a web server. You need to understand at least the basics of HTTP. 3. The web server might be a single python script, or it could be something running behind Apache. You need to understand your web server. 4. The server side of your application might be using any of a number of libraries to connect to the web server (such as Django/Pyramid/Flask/cgi/mod_wsgi etc.). You need to understand whatever mechanism your application is using to speak HTTP. 5. Your application can use SQLAlchemy and GeoAlchemy to retrieve data from postgis into Python data structures. You will need to understand postgis, SQLAlchemy, GeoAlchemy and Python. 6. Your application can then convert those Python data structures into GeoJSON. You will need to understand GeoJSON. The SQLAlchemy mailing list can help you with exactly one part of this (step 5). SQLAlchemy (and GeoAlchemy) is perfectly capable of querying multiple tables and retrieving results. But how you accept the HTTP request, and how you pass the results back, are completely outside the scope of this list and I'm afraid you are unlikely to find much help here with it. Sorry I can't be more help, Simon -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
