Re: Possible to see sql for queryset before database gets it?

[phoebebright]

Thanks for those tips.  Great help.

On Jan 19, 12:37 am, Malcolm Tredinnick 
wrote:
> On Sun, 2009-01-18 at 17:46 -0200, Ramiro Morales wrote:
>
> []
>
>
>
> > or if you are using a recent trunk version (more recent than two weeks or 
> > so)
> > you might want to try printing the output of:
>
> > .as_sql()
>
> Please don't recommend that one, it's very likely to change in the near
> future (like, this week some time), as I'm becoming unhappy with the
> name choice for the reasons given below.
>
> I was trying to keep the internal code clean by not having to if-case
> yet another method name.. The problem with the current method name is
> that it leaks the "SQL" concept into QuerySets, which should, ideally,
> be agnostic about what the storage method is. Unnecessarily leaky
> abstraction and it's keeping me awake at night.
>
> Every QuerySet that has some kind of backing store should have a "query"
> attribute and, if it supports SQL, will have an as_sql() method. (The
> previous sentence is written in a very future-proof fashion. It's
> trivially true for Django at the moment.) The queryset.query.as_sql()
> method is the best way to look at the generated SQL.
>
> Regards,
> Malcolm
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Re: Possible to see sql for queryset before database gets it?

[Malcolm Tredinnick]

On Sun, 2009-01-18 at 17:46 -0200, Ramiro Morales wrote:
[]
> 
> or if you are using a recent trunk version (more recent than two weeks or so)
> you might want to try printing the output of:
> 
> .as_sql()

Please don't recommend that one, it's very likely to change in the near
future (like, this week some time), as I'm becoming unhappy with the
name choice for the reasons given below.

I was trying to keep the internal code clean by not having to if-case
yet another method name.. The problem with the current method name is
that it leaks the "SQL" concept into QuerySets, which should, ideally,
be agnostic about what the storage method is. Unnecessarily leaky
abstraction and it's keeping me awake at night.

Every QuerySet that has some kind of backing store should have a "query"
attribute and, if it supports SQL, will have an as_sql() method. (The
previous sentence is written in a very future-proof fashion. It's
trivially true for Django at the moment.) The queryset.query.as_sql()
method is the best way to look at the generated SQL.

Regards,
Malcolm


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Re: Possible to see sql for queryset before database gets it?

[Ramiro Morales]

On Sun, Jan 18, 2009 at 5:27 PM, phoebebright  wrote:
>
> I have a problem with the sql being generated by this:
>
>tasks = Task.objects.filter(status='open').order_by('-priority')
>tasks = tasks.extra(where=['list IN %s'], params=
> [settings.MY_LISTS])
>
> Is there a command where I can say something like 'print tasks.sql'
> that would generate the sql but not send it to the database, so I can
> see exactly why the sql is failing?

First, you can try what's suggested at this Django FAQ entry:

http://docs.djangoproject.com/en/dev/faq/models/#how-can-i-see-the-raw-sql-queries-django-is-running

For another option, try printing the output of:

.query.as_sql()

or if you are using a recent trunk version (more recent than two weeks or so)
you might want to try printing the output of:

.as_sql()

They should print the complete SQL query generated by the
QuerySet.

Both the query  attribute  and as_sql() method are internal implementation
details of QuerySet. That's why they are not documented, but you can count
on them being present for the foreseeable future.

HTH

-- 
 Ramiro Morales

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