Entity, Field and named_field usage

Entity usage

This class brings the build it in methods:

• to_dict: Will take all properties of the created class and will convert it into a dict instance.

• from_dict: This will take a dict instance and will set the values of every key into a model property with the same name.

• from_record: It takes an ordered Iterable object with the name of the fields that will be loaded into the model, and a tuple with the corresponding values

Entity models will be used with simple class properties or can be used with the Field descriptor of the package

Simple properties

from pydbrepo import Entity

class Model(Entity):
    id = None
    name = None

model = Model.from_dict({"id": 1, "name": "some"})
# Model({"id": 1, "name": "some"})

print(model.id) # => 1
print(model.name) # => some

Property decorators

from pydbrepo import Entity

class Model(Entity):
    def __init__(self):
        super().__init__()

        self.id = None
        self.name = None

    @property
    def id(self):
        return self._id

    @id.setter
    def id(self, value):
        self._id = value

    @property
    def name(self):
        return self._name

    @name.setter
    def name(self, value):
        self._name = value

model = Model.from_dict({"id": 1, "name": "some"})
# Model({"id": 1, "name": "some"})

print(model.id) # => 1
print(model.name) # => some

Field descriptor

from pydbrepo import Entity, Field, named_fields

@named_fields
class Model(Entity):
    id = Field(type_=int)
    name = Field(type_=str)

model = Model.from_dict({"id": 1, "name": "some"})
# Model({"id": 1, "name": "some"})

print(model.id) # => 1
print(model.name) # => some

Casting values with Field descriptor

from uuid import UUID
from pydbrepo import Entity, Field, named_fields

@named_fields
class Model(Entity):
    id = Field(type_=(UUID, str), cast_to=UUID, cast_if=str)
    name = Field(type_=str)

model = Model.from_dict({"id": '10620c02-d80e-4950-b0a2-34a5f2d34ae5', "name": "some"})
# Model({"id": UUID('10620c02-d80e-4950-b0a2-34a5f2d34ae5'), "name": "some"})

print(model.id) # => 10620c02-d80e-4950-b0a2-34a5f2d34ae5
print(model.name) # => some

Casting from a callback function

from datetime import date, datetime
from pydbrepo import Entity, Field, named_fields

def cast_epoch(value):
    if isinstance(value, date):
        return int(value.strftime("%s"))

    if isinstance(value, datetime):
        return int(value.timestamp())

@named_fields
class Model(Entity):
    name = Field(type_=str)
    epoch = Field(type_=(int, date, datetime), cast_to=cast_epoch, cast_if=(date, datetime))

model = Model.from_dict({"name": "some", "epoch": datetime.now()})
# Model({"name": "some", "epoch": 1231231231})

print(model.name) # => some
print(model.epoch) # => 1231231231

Iterable fields and casting with Field descriptor

from pydbrepo import Entity, Field, named_fields

@named_fields
class Item(Entity):
    name = Field(type_=str)
    price = Field(type_=float)

@named_fields
class Model(Entity):
    id = Field(type_=int)
    name = Field(type_=str)
    items = Field(type_=list, cast_items_to=Item)

model = Model.from_dict({
    "id": 1,
    "name": "some",
    "items": [
        {"name": "some", "price": 5.99},
        {"name": "nothing", "price": 6.99},
    ]
})
# Model({"id": 1, "name": "some", "items": [Item({"name": "some", "price": 5.99}), Item({"name": "nothing", "price": 6.99})]})

print(model.id) # => 1
print(model.name) # => some
print(model.items) # => [Item({"name": "some", "price": 5.99}), Item({"name": "nothing", "price": 6.99})]
print(model.items[0].price) # => 5.99