Encapulated object creation in python

Question

I am working with flask and redis. I've decided to try the rom redis orm (http://pythonhosted.org/rom/) to manage some mildly complex data structures. I have a list of objects, lets say:

urls = ['www.google.com', 'www.example.com', 'www.python.org']

I also have the rom model:

class Stored_url(rom.Model):
    url = rom.String(required=True, unique=True, suffix=True)
    salt = rom.String()
    hash = rom.String()
    created_at = rom.Float(default=time.time)

What is the best way to cycle through my urls, turning each into a Stored_url object?

For example the first object would look like:

url = "google.com"
salt = ""
hash = ""
created_at = "the current time"

Edit: the example in the docs has:

user = User(email='[email protected]')
user.salt, user.hash = gen_hash(password)
user.save()

# session.commit() or session.flush() works too

Matt Habel · Accepted Answer · 2015-07-20 17:15:15Z

1

You can do this using list comprehensions, something like:

objects = [Stored_url(url=u) for u in urls]

This will create a new list with one Stored_url object for each url in the original urls list.

To then save these objects, you need to loop through the object list and call save() on each of them:

for o in objects:
    o.save()

edited Jul 20, 2015 at 17:15

answered Jul 20, 2015 at 15:34

Matt Habel

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5 Comments

user1592380 Over a year ago

Matt, thank you. One question in your approach: I will need to save each object (please see my edit above). Can this be incorporated into your method or do I need to iterate through the objects list and save each one?

Matt Habel Over a year ago

Do you need to have access to the objects after you save them or can you discard them? If you need to have access you just need to loop over the objects list and save them, but if you can discard the created objects you can just change that comprehension to [Stored_url(url=u).save() for u in urls]

user1592380 Over a year ago

I need to save them, for later use.

Matt Habel Over a year ago

Then the best way to go about it is to use the method in the original post and then afterwards, loop through the objects list and call save on each object. I'll edit my post

user1592380 Over a year ago

Ok, that helps. Thank you.

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