[PonyORM-list] what is the best way to export sqlite database to csv file with pony ?

[Вадим Бажов]

Hi Alexander. Thank you so lot ! I'll try to_dict() method soon and i 
think that's what i need.
You have a really rapid development workflow there, guys !


08.08.2014 22:16, Alexander Kozlovsky пишет:
> Hi Vadim!
>
> I'd like to inform you that I just added the to_dict() method, which 
> can be useful for converting Pony objects to CSV, JSON or any other 
> format. I want to show you how this method can be used.
>
> At first, let's import a module from Pony ORM examples and get an 
> object which we want to convert to dictionary:
>
>     >>> from pony.orm.examples.presentation import *
>     >>> populate_database()
>     >>> s = Student[1]
>
> Now we can convert this object to a dictionary by the following way:
>
>     >>> s.to_dict()
>     {'group': 101, 'name': u'John Smith', 'dob': datetime.date(1991, 
> 3, 20), 'gpa': 3.0, 'tel': '123-456', 'id': 1}
>
> If we want to extract specific fields only, we can specify the list of 
> attributes:
>
>     >>> s.to_dict(['id', 'name', 'group'])
>     {'group': 101, 'id': 1, 'name': u'John Smith'}
>
> or
>
>     >>> s.to_dict("id name group")
>     {'group': 101, 'id': 1, 'name': u'John Smith'}
>
> By default the related objects are represented by its primary keys, 
> but it is possible to get full objects by specifying 
> `related_objects=True`. This way you can convert related objects 
> recursively:
>
>     >>> s.to_dict(['id', 'name', 'group'], related_objects=True)
>     {'group': Group[101], 'id': 1, 'name': u'John Smith'}
>
> By default, collections and lazy attributes (such as BLOBs) are not 
> included to the to_dict() result. It can be changed by specifying 
> `with_collections=True` and `with_lazy=True`.
>
> Now I want to show how you can store database data to CSV format using 
> standard python csv module and new to_dict() method. Let's store the 
> content of the Student table to the CSV file:
>
>     from pony.orm.examples.presentation import Student
>     import csv
>     fields = ['id', 'name', 'group', 'gpa', 'tel']
>     csv_file = open('students.csv', 'w')
>     writer = csv.DictWriter(csv_file, fields)
>     writer.writeheader()
>     for s in Student.select():
>         writer.writerow(s.to_dict(fields))
>     csv_file.close()
>
> If you want to export all entity attributes in the same order as they 
> defined, you can write universal function like this:
>
>     def export_to_csv(entity, filename):
>         fields = [ attr.name <http://attr.name> for attr in 
> entity._attrs_with_columns_ if not attr.lazy ]
>         with open(filename, 'wb') as f:
>             writer = csv.DictWriter(f, fields)
>             writer.writeheader()
>             for obj in entity.select():
>                 writer.writerow(obj.to_dict(fields))
>
> Then you can use this function in the following way:
>
>     export_to_csv(Student, 'students.csv')
>
> to_dict() method is available in Pony ORM development version which 
> can be taken from GitHub:
> https://github.com/ponyorm/pony
>
> We plan to release the new version Pony ORM 0.5.2 on Monday which 
> includes to_dict() method, and you will be able to install it from 
> PyPI using
> pip install pony --upgrade
>
>
> Regards,
> Alexander
>
>
>
> On Mon, Aug 4, 2014 at 6:53 PM, Вадим Бажов <vadim at ideco.ru
> <mailto:vadim at ideco.ru>> wrote:
>
>     Hi, folks !
>     I created and filled an sqlite db with data using Pony ORM. It's
>     clean and easy.
>     Now i need to be able to convert the database to windows
>     Excell-friendly representation for the hiegher autority.
>     As i suppose, the csv is the most easy and suitable file format
>     for that case.
>     So, please, share your experiences with me what is the best way to
>     do such an export with Pony? If pony hasn't such export ability
>     (what i didn't find), tell me what tools do you usually use for
>     that task?
>
>     -- 
>     С уважением,
>     Бажов Вадим,
>     Инженер отдела технической поддержки,
>     Компания Айдеко
>     --
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>
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>
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-- 
С уважением,
Бажов Вадим,
Инженер отдела технической поддержки,
Компания Айдеко
--
Телефоны: +7 (495) 987-32-70; +7 (495) 662-87-34 (тех. поддержка); +7 (343) 345-15-75; Факс: +7 (343) 383-75-13

Электронная почта:
Вопросы по приобретению: sales at ideco.ru
Технические вопросы: support at ideco.ru
Партнерство: partners at ideco.ru
Общие вопросы: info at ideco.ru

Сайт: http://www.ideco.ru/
Форум: http://www.ideco.ru/forum/

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