Dict

Generating dynamic json object based on model. This is one of the most powerful feature of using models

Generating json based on model

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Let's imagine that we have a user object, and we need to get this object with random values each time

{
  "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "username": "some random username",
  "email": "some random email"
}

So let's create a model which will generate us json above

Note

Id should be dynamic value. Usually when we write auto tests, we use dynamic values. Just like our API can't always accept static values, and vice versa they must be unique each time

import uuid

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


class User(Model):
    id = Field(default=uuid.uuid4, json='id', category=str)
    username = Field(default=random_string, json='username', category=str)
    email = Field(default=random_string, json='email', category=str)

Let's see what's going on here

import uuid

from models_manager.utils import random_string

callable(uuid.uuid4)  # True
callable(random_string)  # True

callable(uuid.uuid4())  # False 
callable(random_string())  # False 

In this case, uuid4, random_string are callable objects. When generating json, these objects will be called and return values will be obtained from them

Let's try to use our user model and generate random json

import uuid

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


class User(Model):
    id = Field(default=uuid.uuid4, json='id', category=str)
    username = Field(default=random_string, json='username', category=str)
    email = Field(default=random_string, json='email', category=str)


User.manager.to_dict()
{
    'id': '992ae8a2-ab6d-4d16-a7fd-e009bdcbff4c',
    'username': 'P8aNC414bqfSZEyUVpgZZQt',
    'email': 'UDxG3bKhvlLuM8n1LFCtfbZqwlKihogkL6BM8gfVIVk28'
}

User.manager.to_dict()
{
    'id': 'b3a02f98-7691-4a30-a42d-a1a3c600b584',
    'username': 'XUzl4QLP5mENis0tadeqacSSHf0vwaySeGQgV7S64R2M',
    'email': 'h1OnsjE5s1UXwTeEpuB5GbPPLF8'
}

Now we get random json values every time we call the to_dict() method

Json key

The json_key argument is used to control the keys that will be used when serializing the object into a dictionary

Consider an example where the field names differ from their names in json view

from typing import Optional

from models_manager import Model, Field


class User(Model):
    id = Field(json='Id', category=Optional[str])
    username = Field(json='Username', category=Optional[str])


User.manager.to_dict(json_key=False)
{'id': None, 'username': None}

User.manager.to_dict(json_key=True)
{'Id': None, 'Username': None}

From the example above, we see that if json_key=True, then we get a dictionary with json keys, otherwise we get the original field names

Exclude

To exclude fields that will be in the model dictionary, you can use the exclude parameter. The arguments are a list of Field objects or a list of fields as strings

from models_manager import Model, Field


class User(Model):
    id = Field(json='id', category=int, default=1)
    username = Field(json='username', category=str, default='some')


User.manager.to_dict(exclude=[User.id])
{'username': 'some'}

User.manager.to_dict(exclude=['id'])
{'username': 'some'}

Now we can see that the id field has been excluded from the model dictionary

You can also exclude fields when creating an object

from models_manager import Model, Field


class User(Model):
    id = Field(json='id', category=int, default=1)
    username = Field(json='username', category=str, default='some')


user = User(exclude_dict=[User.id])
user.manager.to_dict()
{'username': 'some'}

user = User(exclude_dict=['id'])
user.manager.to_dict()
{'username': 'some'}

If you specify the fields to be excluded as strings, then you must specify their format in json