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CRUD example

CRUD - Create, Retrieve, Update, Delete are the four basic functions of persistent storage.

This example will show you how to implement these functions with Django Ninja.

Let's say you have the following Django models that you need to perform these operations on:

class Department(models.Model):
    title = models.CharField(max_length=100)

class Employee(models.Model):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    department = models.ForeignKey(Department)
    birthdate = models.DateField(null=True, blank=True)

Now let's create CRUD operations for the Employee model.

Create

To create an employee lets define an INPUT schema:

from datetime import date
from ninja import Schema

class EmployeeIn(Schema):
    first_name: str
    last_name: str
    department_id: int = None
    birthdate: date = None

This schema will be our input payload:

@api.post("/employees")
def create_employee(request, payload: EmployeeIn):
    employee = Employee.objects.create(**payload.dict())
    return {"id": employee.id}

Tip

Schema objects have .dict() attribute with all the schema attributes represented as a dict.

You can pass it as **kwargs to the Django model's create method (or model __init__).

Retrieve

Single object

Now to get employee we will define a schema that will describe what our responses will look like. Here we will basically use the same schema as EmployeeIn, but will add an extra attribute id:

class EmployeeOut(Schema):
    id: int
    first_name: str
    last_name: str
    department_id: int = None
    birthdate: date = None

Note

Defining response schemas are not really required, but when you do define it you will get results validation, documentation and automatic ORM objects to JSON conversions.

We will use this schema as the response type for our GET employee view:

@api.get("/employees/{employee_id}", response=EmployeeOut)
def get_employee(request, employee_id: int):
    employee = get_object_or_404(Employee, id=employee_id)
    return employee

Notice that we simply returned an employee ORM object, without a need to convert it to a dict. The response schema does automatic result validation and conversion to JSON:

@api.get("/employees/{employee_id}", response=EmployeeOut)
def get_employee(request, employee_id: int):
    employee = get_object_or_404(Employee, id=employee_id)
    return employee

List of objects

To output a list of employees, we can reuse the same EmployeeOut schema. We will just set the response schema to a List of EmployeeOut.

from typing import List

@api.get("/employees", response=List[EmployeeOut])
def list_employees(request):
    qs = Employee.objects.all()
    return qs

Another cool trick - notice we just returned a Django ORM queryset:

@api.get("/employees", response=List[EmployeeOut])
def list_employees(request):
    qs = Employee.objects.all()
    return qs

It automatically gets evaluated, validated and converted to a JSON list!

Update

Update is pretty trivial. We just use the PUT method and also pass employee_id:

@api.put("/employees/{employee_id}")
def update_employee(request, employee_id: int, payload: EmployeeIn):
    employee = get_object_or_404(Employee, id=employee_id)
    for attr, value in payload.dict().items():
        setattr(employee, attr, value)
    employee.save()
    return {"success": True}

Note

Here we used the payload.dict method to set all object attributes:

for attr, value in payload.dict().items()

You can also do this more implicit:

employee.first_name = payload.first_name
employee.last_name = payload.last_name
employee.department_id = payload.department_id
employee.birthdate = payload.birthdate

Delete

Delete is also pretty simple. We just get employee by id and delete it from the DB:

@api.delete("/employees/{employee_id}")
def delete_employee(request, employee_id: int):
    employee = get_object_or_404(Employee, id=employee_id)
    employee.delete()
    return {"success": True}

Final code

Here's a full CRUD example:

from datetime import date
from typing import List
from ninja import NinjaAPI, Schema
from django.shortcuts import get_object_or_404
from employees.models import Employee


api = NinjaAPI()


class EmployeeIn(Schema):
    first_name: str
    last_name: str
    department_id: int = None
    birthdate: date = None


class EmployeeOut(Schema):
    id: int
    first_name: str
    last_name: str
    department_id: int = None
    birthdate: date = None


@api.post("/employees")
def create_employee(request, payload: EmployeeIn):
    employee = Employee.objects.create(**payload.dict())
    return {"id": employee.id}


@api.get("/employees/{employee_id}", response=EmployeeOut)
def get_employee(request, employee_id: int):
    employee = get_object_or_404(Employee, id=employee_id)
    return employee


@api.get("/employees", response=List[EmployeeOut])
def list_employees(request):
    qs = Employee.objects.all()
    return qs


@api.put("/employees/{employee_id}")
def update_employee(request, employee_id: int, payload: EmployeeIn):
    employee = get_object_or_404(Employee, id=employee_id)
    for attr, value in payload.dict().items():
        setattr(employee, attr, value)
    employee.save()
    return {"success": True}


@api.delete("/employees/{employee_id}")
def delete_employee(request, employee_id: int):
    employee = get_object_or_404(Employee, id=employee_id)
    employee.delete()
    return {"success": True}