Re: query join tables

2014-10-13 Thread Jani Tiainen 
On Sun, 12 Oct 2014 22:01:51 -0700 (PDT)
dk  wrote:

> I have this 2 models
> 
> class Choice(models.Model):
> restaurant = models.ForeignKey(Restaurant)
> person = models.ForeignKey(Person)
> date = models.DateField("time published")
> time = models.TimeField("date published")
> 
> class Person(models.Model):
> name = models.CharField(max_length=100)
> last_name = models.CharField(max_length=100)
> email = models.EmailField()
> 
> and I would like to be able to see check if in a certain date, a certain 
> person does exist in the record.
> I am currently querying the date first.
> 
> date_query = Choice.objects.filter(date=dater)
> for i in date_query:
> if i.person_id == to_email_i_am_looking:
> 
> might be another way to chain the querys? 
> kinda
> 
> SELECT person  FROM choice JOIN people
> ON choice.person_ID=person+ID; 
> WHERE date= today and person=someone
> ?
> 
> I read about select_related that use the ForeignKey,  but I have 2 in my 
> case,  the person and the restaurant,  does it loop on bouth?

You can leverage reverse relation managers rather easily:

If you do have a person available already you can do the following:

choices_for_person_on_date = person.choice_set.filter(date=dater)

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Jani Tiainen

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Re: query join tables

2014-10-13 Thread Anderson 
HI there..

Looks like you already have the person ID , you don't need hit the database
every time  to call Person object.
You can make faster only check for ID not Person object.

instead this:

person = Person.objects.get(name=person_name)
choices_for_person_on_date =
Choice.objects.filter(date=dater).filter(person=person)


You can do this

choices_for_person_on_date = Choice.objects.get(date=dater,person_id =
to_email_i_am_looking)

and if you want the joins


Choice.objects.get(date=dater,person_id =
to_email_i_am_looking).select_related('person')




On Mon, Oct 13, 2014 at 4:21 AM, dk  wrote:

> I will give a try,   how does django know that have to join  using double
> filter? or it just auto-magically knows behind the hood?
> or filtering by another model/class django get the idea, and joins the
> tables?
>
> Thanks Tom =)
>
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Re: query join tables

2014-10-13 Thread dk 
I will give a try,   how does django know that have to join  using double 
filter? or it just auto-magically knows behind the hood?
or filtering by another model/class django get the idea, and joins the 
tables?

Thanks Tom =)

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Re: query join tables

2014-10-12 Thread Tom Lockhart 
On Oct 12, 2014, at 10:01 PM, dk  wrote:

> I have this 2 models
> 
> class Choice(models.Model):
> restaurant = models.ForeignKey(Restaurant)
> person = models.ForeignKey(Person)
> date = models.DateField("time published")
> time = models.TimeField("date published")
> 
> class Person(models.Model):
> name = models.CharField(max_length=100)
> last_name = models.CharField(max_length=100)
> email = models.EmailField()
> 
> and I would like to be able to see check if in a certain date, a certain 
> person does exist in the record.
> I am currently querying the date first.
> 
> date_query = Choice.objects.filter(date=dater)
> for i in date_query:
> if i.person_id == to_email_i_am_looking:
> 
> might be another way to chain the querys?

You can chain together the filters:

person = Person.objects.get(name=person_name)
choices_for_person_on_date = 
Choice.objects.filter(date=dater).filter(person=person)

hth

- Tom

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query join tables

2014-10-12 Thread dk 
I have this 2 models

class Choice(models.Model):
restaurant = models.ForeignKey(Restaurant)
person = models.ForeignKey(Person)
date = models.DateField("time published")
time = models.TimeField("date published")

class Person(models.Model):
name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100)
email = models.EmailField()

and I would like to be able to see check if in a certain date, a certain 
person does exist in the record.
I am currently querying the date first.

date_query = Choice.objects.filter(date=dater)
for i in date_query:
if i.person_id == to_email_i_am_looking:

might be another way to chain the querys? 
kinda

SELECT person  FROM choice JOIN people
ON choice.person_ID=person+ID; 
WHERE date= today and person=someone
?

I read about select_related that use the ForeignKey,  but I have 2 in my 
case,  the person and the restaurant,  does it loop on bouth?


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