Object model

Basic

Working with models can be working with objects

Let's create an object based on the model

from models_manager import Model, Field


class User(Model):
    id = Field(json='id', category=int)
    username = Field(json='username', category=str)
    email = Field(json='email', category=str)


user = User(id=1, username='some', email='other')

user.id
'<Field: 1>'

user.id.value
1

Warning

Note that user.id does not return an id value, but a field object that contains data about this field

Now let's take a closer look at how we can manipulate our object.

from models_manager import Model, Field


class User(Model):
    id = Field(json='id', category=int)
    username = Field(json='username', category=str)
    email = Field(json='email', category=str)


user = User(id=1, username='some', email='other')

user.manager.to_dict()
{'id': 1, 'username': 'some', 'email': 'other'}

From the example above, you can see that our object has a manager attribute. With which we can receive the object as a dictionary, generate a schema, use the object to interact with the database, and so on.

List of objects

Now let's complicate our model and add nested objects to it.

from typing import List

from models_manager import Model, Field


class Tenant(Model):
    id = Field(json='id', category=int)
    name = Field(json='name', category=str)


class User(Model):
    id = Field(json='id', category=int)
    username = Field(json='username', category=str)
    email = Field(json='email', category=str)
    tenants = Field(json='tenants', category=List[Tenant])


tenants = [Tenant(id=1, name='some'), Tenant(id=2, name='Other')]
user = User(id=1, username='some', email='other', tenants=tenants)

We have now added a tenants field to our user, which contains a list of Tenant objects. Now, when creating an object, we specify the tenants parameter and pass a list with Tenant objects there

Now let's try to get the value of the tenants field and generate a dictionary

from typing import List

from models_manager import Model, Field


class Tenant(Model):
    id = Field(json='id', category=int)
    name = Field(json='name', category=str)


class User(Model):
    id = Field(json='id', category=int)
    username = Field(json='username', category=str)
    email = Field(json='email', category=str)
    tenants = Field(json='tenants', category=List[Tenant])


tenants = [Tenant(id=1, name='some'), Tenant(id=2, name='Other')]
user = User(id=1, username='some', email='other', tenants=tenants)

user.tenants.value
'[<Model: Tenant>, <Model: Tenant>]'

user.manager.to_dict()
{
    'id': 1,
    'username': 'some',
    'email': 'other',
    'tenants': [
        {'id': 1, 'name': 'some'},
        {'id': 2, 'name': 'Other'}
    ]
}

From the example above, we see that inside the Users model there are a tenants attribute that contains a list of Tenant objects. When we serialize this object using the to_dict() method, we get a nested object structure

Dictionary with object

Now let's look at an example in which we will have a dictionary with an object inside

from typing import Dict

from models_manager import Model, Field


class Tenant(Model):
    id = Field(json='id', category=int)
    name = Field(json='name', category=str)


class User(Model):
    id = Field(json='id', category=int)
    username = Field(json='username', category=str)
    email = Field(json='email', category=str)
    tenant_ref = Field(json='tenantRef', category=Dict[str, Tenant])


tenant_ref = {'some': Tenant(id=1, name='some')}
user = User(id=1, username='some', email='other', tenantRef=tenant_ref)

Now we have added the tenant_ref field, which is a dictionary, and inside this dictionary we have a Tenant object. Let's generate a dictionary based on the User model and look at the value of the tenant_ref field

Warning

Notice that when we created the User object, we specified the tenantRef attribute, not the tenant_ref attribute. When generating a model object, the names of the attributes are passed in the form in which they appear in the json representation

from typing import Dict

from models_manager import Model, Field


class Tenant(Model):
    id = Field(json='id', category=int)
    name = Field(json='name', category=str)


class User(Model):
    id = Field(json='id', category=int)
    username = Field(json='username', category=str)
    email = Field(json='email', category=str)
    tenant_ref = Field(json='tenantRef', category=Dict[str, Tenant])


tenant_ref = {'some': Tenant(id=1, name='some')}
user = User(id=1, username='some', email='other', tenantRef=tenant_ref)

user.tenant_ref.value
"{'some': <Model: Tenant>}"

user.manager.to_dict()
{
    'id': 1,
    'username': 'some',
    'email': 'other',
    'tenantRef': {
        'some': {'id': 1, 'name': 'some'}
    }
}

From the example above, we can see that the dictionary with the object was serialized when the to_dict() method was called.