CRUD operations

Let's create a simple table and use it as an example to analyze the operations of reading, creating, updating, deleting

Our "user" database table

id	username	email
1	some1	email1
2	some2	email2
3	some3	email3

Our python model

from models_manager import Model, Field
from models_manager.utils import random_number, random_string


class User(Model):
    identity = 'users'
    database = 'stuff'

    id = Field(default=random_number, category=int)
    username = Field(default=random_string, category=str)
    email = Field(default=random_string, category=str)

    def __str__(self):
        return f'<User: {self.id}>'

Get

Get always returns a single object. If the requested object is not in the database, it will raise an error

User.manager.get(id=1)  # returns python dict
{
    'id': 1,
    'username': 'some1',
    'email': 'email1'
}

User.manager.get(id=1, as_json=False)  # returns user object
'<User: 1>'

User.manager.get(id=100)  # user with id 100 does not exists
"ModelDoesNotExists: 'User' with {'id': 100} does not exists"

Filter

Filter returns a list of objects. If the objects are not found in the database, it will return an empty list

User.manager.filter(id=1)  # returns python list of dicts
[
    {
        'id': 1,
        'username': 'some1',
        'email': 'email1'
    }
]

User.manager.filter(id__in=(1, 2), as_json=False)  # returns list of user objects
['<User: 1>', '<User: 2>']

# no such users in our database, filter will return empty list
User.manager.filter(id__in=(100, 200))
[]

Create

Creates an object and returns the created object. Values for creation are taken from the fields of the model

User.manager.create()  # create user with some random values
{
    'id': 9,
    'username': 'pF8i78S0ncdatjR5UDYE6uMDg5yxEwLk',
    'email': 'i7KbUPGrNGBr5yW9mu6lD6JPMxX3FnKCaTQlSuwR9fLM'
}

# override username with custom value, instead of random
User.manager.create(username='custom')
{
    'id': 32,
    'username': 'custom',
    'email': 'BzpzI8cc54ztqJLCgo7gUCYe8BhGzZxgt7c63l'
}

User.manager.create(id=100, as_json=False)  # returns user object
'<User: 100>'

Update

Allows you to update the object. Returns the updated object

user = User.manager.get(id=1, as_json=False)
user = user.manager.update(username='new_username', as_json=False)

user  # returns user object
'<User: 1>'

user.username  # updated username value
'new_username'

Delete

Removes an object from the database. Returns nothing

user = User.manager.get(id=1, as_json=False)
user.manager.delete()  # deleting user object with id=1

Is exists

Return a boolean, True if the entities are present in the database, False if the entities are not in the database. Recommended to use to check the presence of an entity in the database

is_user_exists = User.manager.is_exists(id=1)

is_user_exists  # user with id=1 exists, True
True

is_user_exists = User.manager.is_exists(id=100)

is_user_exists  # user with id=100 does not exists, False
False