Re: How to use subqueries in django

[Radhikavk]

thank you sir i found the solution
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Re: How to use subqueries in django

[Karen Tracey]

On Wed, Nov 18, 2009 at 2:15 AM, Radhikavk  wrote:

>
> in one query they have giver or conditions
> but i need
> i wil have one common query like
> list=rooms.objects.all()  # this is common query i m using
>
> and if the condition given like room status,type etc then i need to append
> those where conditions to the common query
> if room_type
>  append where room_type=this
> else
> nothing
>
> i have so many search criteria , i think this appending is useful but it is
> giving error queryset has no attribute append
>

Certainly it is useful, but in the Django ORM it is not done by calling a
method named append.  It is done by chaining filter calls.  Please read:

http://docs.djangoproject.com/en/dev/topics/db/queries/#id1

Karen

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Re: How to use subqueries in django

[Radhikavk]

in one query they have giver or conditions 
but i need
i wil have one common query like 
list=rooms.objects.all()  # this is common query i m using

and if the condition given like room status,type etc then i need to append
those where conditions to the common query  
if room_type
  append where room_type=this
else
 nothing

i have so many search criteria , i think this appending is useful but it is
giving error queryset has no attribute append

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Re: How to use subqueries in django

[Adam Knight]

On Nov 17, 2009, at 7:49 AM, Radhikavk wrote:

> 
> hi,
> 
> how to use search criteria using OR and AND in queries
> user can search room by no,room_type, block etc i need the combination 
> 
> 
> Please can you refer the tutorial

http://docs.djangoproject.com/en/dev/topics/db/queries/#complex-lookups-with-q-objects

Adam Knight
codepoetry - http://www.codepoetry.net/products/




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Re: How to use subqueries in django

[Radhikavk]

hi,

how to use search criteria using OR and AND in queries
user can search room by no,room_type, block etc i need the combination 


Please can you refer the tutorial
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Re: How to use subqueries in django

[Radhikavk]

Karen Tracey-2 wrote:
> 
> On Tue, Nov 17, 2009 at 6:43 AM, Radhikavk <radhi3...@gmail.com> wrote:
> 
>>
>> I tried this i dis not get solution
>>
>> i m getting a list from rooms table
>>
>> room_list=rooms.objects.all()
>>
>> This will give me the room type id when i print room_list.room_type_id
>> but
>> for this id i need a name which is in room_types table
>>
> 
> room_list as you have assigned it above won't have a room_type_id so I'm
> confused by what you are saying you can do -- what you say you can do
> would
> produce an error.
> 
> room_list is a QuerySet, you first need to pull an individual instance of
> a
> rooms model out of the set before you can access any of its attributes
> such
> as room_type.  Once you have a rooms instance, it will have a rooms_type
> instance in its room_type attribute.  From the rooms_type instance you can
> access any of its attributes using standard Python dot notation.  For eg:
> 
> for room in room_list:
> print 'Room type is: %s' % room.room_type.room_type_name
> 
> If you have not worked through the tutorial I encourage you to do so:
> 
> http://docs.djangoproject.com/en/dev/intro/tutorial01/
> 
> Also you might find this section of the documentation helpful:
> 
> http://docs.djangoproject.com/en/dev/topics/db/queries/#related-objects
> 
> Karen
> 
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> 
> 
> 
> 

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Re: How to use subqueries in django

[Radhikavk]

ok i got it 

Thanks
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Re: How to use subqueries in django

[Karen Tracey]

On Tue, Nov 17, 2009 at 6:43 AM, Radhikavk  wrote:

>
> I tried this i dis not get solution
>
> i m getting a list from rooms table
>
> room_list=rooms.objects.all()
>
> This will give me the room type id when i print room_list.room_type_id but
> for this id i need a name which is in room_types table
>

room_list as you have assigned it above won't have a room_type_id so I'm
confused by what you are saying you can do -- what you say you can do would
produce an error.

room_list is a QuerySet, you first need to pull an individual instance of a
rooms model out of the set before you can access any of its attributes such
as room_type.  Once you have a rooms instance, it will have a rooms_type
instance in its room_type attribute.  From the rooms_type instance you can
access any of its attributes using standard Python dot notation.  For eg:

for room in room_list:
print 'Room type is: %s' % room.room_type.room_type_name

If you have not worked through the tutorial I encourage you to do so:

http://docs.djangoproject.com/en/dev/intro/tutorial01/

Also you might find this section of the documentation helpful:

http://docs.djangoproject.com/en/dev/topics/db/queries/#related-objects

Karen

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Re: How to use subqueries in django

[Radhikavk]

I tried this i dis not get solution 

i m getting a list from rooms table 

room_list=rooms.objects.all()

This will give me the room type id when i print room_list.room_type_id but
for this id i need a name which is in room_types table

how to get this

Thanks
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Re: How to use subqueries in django

[Daniel Roseman]

On Nov 17, 10:26 am, Radhikavk <radhi3...@gmail.com> wrote:
> Hi ,
>
> I have 2 tables room_types and room
>
> the table structure
>
> class room_types(models.Model):
>     room_type_id = models.AutoField(primary_key=True,null=False,blank=False)
>     room_type_name =
> models.CharField(max_length=100,unique=True,null=False,blank=False)
>     room_type_desc = models.TextField(null=True)
>     standard_occupancy = models.IntegerField()
>     higher_occupancy = models.IntegerField()
>     base_price = models.DecimalField(max_digits=8, decimal_places=2)
>     higher_price = models.DecimalField(max_digits=8, decimal_places=2)
>     status = models.ForeignKey('common.status')
>
> class rooms(models.Model):
>     room_no
> =models.IntegerField(primary_key=True,null=False,blank=False,unique=True)
>     room_desc=models.TextField(null=True)
>     room_type=models.ForeignKey('room_types')
>     block=models.ForeignKey('blocks')
>     floor=models.IntegerField()
>     room_status=models.ForeignKey('room_status')
>
> Here room_type_id is pk in room_types and is fk in rooms table
>
> and to display the list of rooms the quesry should be
>
> select r.room_type_id,r.room_no,rt.room_type_name from room_types rt,rooms r
> where rt.room_type_id=r.room_type_id
>
> How to give this query in django
>
> Thanks in advance
>
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> View this message in 
> context:http://old.nabble.com/How-to-use-subqueries-in-django-tp26387486p2638...
> Sent from the django-users mailing list archive at Nabble.com.

You don't need to do anything. Every room has a 'room_type' field so
room.room_type. room_type_name will give you the room type name.

You can make it a bit more efficient by using select_related when you
get the initial queryset.
--
DR.

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How to use subqueries in django

[Radhikavk]

Hi ,

I have 2 tables room_types and room

the table structure

class room_types(models.Model):
room_type_id = models.AutoField(primary_key=True,null=False,blank=False)
room_type_name =
models.CharField(max_length=100,unique=True,null=False,blank=False)
room_type_desc = models.TextField(null=True)
standard_occupancy = models.IntegerField()
higher_occupancy = models.IntegerField()
base_price = models.DecimalField(max_digits=8, decimal_places=2)
higher_price = models.DecimalField(max_digits=8, decimal_places=2)
status = models.ForeignKey('common.status')


class rooms(models.Model):
room_no
=models.IntegerField(primary_key=True,null=False,blank=False,unique=True)
room_desc=models.TextField(null=True)
room_type=models.ForeignKey('room_types')
block=models.ForeignKey('blocks')
floor=models.IntegerField()
room_status=models.ForeignKey('room_status')


Here room_type_id is pk in room_types and is fk in rooms table

and to display the list of rooms the quesry should be

select r.room_type_id,r.room_no,rt.room_type_name from room_types rt,rooms r
where rt.room_type_id=r.room_type_id

How to give this query in django 

Thanks in advance


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