Hey Mike,
Yeah, I see the problem -- didn't mean it to come across as criticism of how
things are! :)
Personally, I'm a big fan of extreemly verbose error messages, with
suggestions, sample code, or even usage cases when possible -- either in the
error message itself or referenced by an error number somewhere in the docs.
I'm not saying it's critical, but are you in a position to offer any
constructive first-level advice like "Are all the tables explicitly related to
eachother?" or "Did you forget to add a secondary table to the 'relation()'
argument?" or something equivilent?
Maybe just having it note back to a specific place in the documentation for
future suggestions, steps to repro and solve?
-G
On Sunday, April 23, 2006, 11:09:44 PM, you wrote:
> hey gambit -
> a cohesive error message begins as what it literally is before it can
> be refined into a more descriptive case, based on observation of what
> actually makes it occur. when i wrote that message, i had no idea
> what conditions would create it. now we are getting a better idea so
> its a candidate for a text change, along the lines of "primary join
> does not contain required table 'X'". does that help ?
> On Apr 23, 2006, at 4:13 PM, Gambit wrote:
>> Hey Mike,
>>
>> Speaking from a debugging point of view, it might be useful if
>> error messages
>> get more text then just "it failed, and died". Even if you just
>> attached your
>> paragraph at the bottom starting "So when the..." either to the
>> error itself
>> (always useful!) or somewhere in the docs (which, docstrings or no,
>> don't have
>> any instances of 'syncrule' in them) it would put that snippet in
>> the first
>> couple of places someone encountering the error is going to look.
>> So maybe a
>> "Error Messages" section at the end of the docs?
>> -G
>>
>> On Sunday, April 23, 2006, 9:42:49 PM, you wrote:
>>> a syncrule is an object generated internally when you associate one
>>> Mapper with another Mapper via a relation(), which is actually an
>>> object called a PropertyLoader.
>>
>>> so lets use the Users/Address example. say we have classes User and
>>> Address. the join condition is
>>> users.c.user_id==addresses.c.user_id . When you attach the Address
>>> to the User and do a save, the "user_id" property of the User object
>>> is copied to the Address object. That is done by a syncrule. The
>>> syncrule is generated at mapper construction time by looking at the
>>> tables inside of "users.c.user_id==addresses.c.user_id", i.e. "users"
>>> and "addresses", matching those up to the mappers for the User and
>>> Address classes, and correlating the "user_id" column to the
>>> appropriate attribute in the User and Address class. the SyncRule
>>> then has an execute() method that is called at save time, which
>>> copies a single attribute from source to destination, in this case
>>> copying the "user_id" attribute from a User object to an Address
>>> object.
>>
>>> So when the relation system has that error with "no syncrules
>>> generated", its a sign that the join conditions of the relationship
>>> do not correspond to the tables represented by the mappers.
>>
>>> the code for this is pretty well isolated and docstring'ed in the
>>> module sqlalchemy.mapping.sync, containing the two objects
>>> ClauseSynchronizer and SyncRule.
>>
>>
>>> On Apr 23, 2006, at 1:50 PM, Gambit wrote:
>>
>>>> Hey All,
>>>>
>>>> For the line:
>>>> Customer.mapper.add_property('checkout_history', relation
>>>> (CheckoutEntry.mapper, t_customer_tours,
>>>> primaryjoin=Customer.c.cust_id==CustomerTour.c.cust_id,
>>>> secondaryjoin=and_(CustomerTour.c.start_date <=
>>>> CheckoutEntry.c.ts_checkout,
>>>>
>>>>
>>>> CoreDb.CustomerTour.c.finish_date >= CheckoutEntry.c.ts_checkout)))
>>>> it generates the following error:
>>>>
>>>> ArgumentError: No syncrules generated for join criterion
>>>> customer_tours.start_date <= checkout_trail.ts_checkout AND
>>>> customer_tours.finish_date >= checkout_trail.ts_checkout
>>>>
>>>> It turns out that that property is, well, not what I wanted in the
>>>> first place
>>>> (there's no explicit 1:1 relationship between Customer and
>>>> CustomerTour,
>>>> amongst other things) but I am pretty curious what a syncrule is,
>>>> what causes
>>>> it to be generated (or not generated), and, if I encounter it
>>>> again, what
>>>> should I look for?
>>>>
>>>> I'm sure it must make sense to /someone/, but as a user I'm left
>>>> scratching my
>>>> head :)
>>>>
>>>> Cheers,
>>>> -G
>>>>
>>>>
>>>>
>>>>
>>>> -------------------------------------------------------
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>>
>>
>>
>> -------------------------------------------------------
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>> Get stuff done quickly with pre-integrated technology to make your
>> job easier
>> Download IBM WebSphere Application Server v.1.0.1 based on Apache
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>> cmd=lnk&kid=120709&bid=263057&dat=121642
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> -------------------------------------------------------
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