Saving and Deleting Objects in in DRF

How to Save Objects in Django Rest Framework?

In the Django REST framework (DRF), you can use the built-in views and serializers to save objects to the database. Saving objects in the Django REST framework (DRF) typically involves several steps:

• Define a serializer class: that specifies how the object should be converted to and from JSON. This serializer class should be a subclass of serializers.ModelSerializer and should define the fields of the object that should be exposed in the API, as well as any validation rules for those fields.
• Create a view class: that handles the creation of new objects. The view class should be a subclass of one of DRF's built-in views, such as APIView or ModelViewSet. In the view class, you should specify the serializer class that should be used for handling the data, and the POST method should be overridden to handle the creation of the object.
• Add the view to your URL routing configuration: so that it's accessible to clients.
• Test the endpoint: by sending a POST request to the appropriate endpoint with a JSON payload that contains the data for the object to be created.

Here's an example of how you might implement this in code:

In this example, when a client sends a POST request with a JSON payload to the endpoint /person/, the post method of the PersonCreateView is invoked. The post method uses the PersonSerializer to validate the data, and if the data is valid, it calls the save method on the serializer to save the data to the database and return the object created in the API response.

Saving Multiple Objects

Saving and Deleting Objects in django includes saving multiple objects is typically done by iterating over a list of data and saving each object individually. However, when working with many objects, this approach can be inefficient, as it results in multiple database queries.

One way to optimize this process is to use the bulk_create() method, which allows you to create multiple objects in a single database query. The bulk_create() method is available on the manager of your model, and it takes a list of objects as its argument.

Here's an example of how you might use the bulk_create() method to create multiple objects of the same model:

This will create multiple MyModel instances in a single query, this way it's faster than creating objects one by one. Also, you can use the django-bulk-update library that provides more efficient bulk operations than the bulk_create of Django ORM.

In Django REST Framework (DRF), you can save multiple objects in a single request using the ListSerializer class. You can define a serializer that inherits from ListSerializer and use it to validate and save multiple objects in the request data.

Here's an example of how you might use a ListSerializer to create multiple objects:

You can use MyModelCreateSerializer in your view to handle the creation of multiple MyModel instances in a single request. You also need to put many=True in the serializer argument of views.

How to Safely Delete Objects?

Saving and Deleting Objects in Django REST Framework (DRF) provides safe delete objects by using the destroy() method of the views. This method handles the deletion of a single object and automatically sends a 204 No Content response to the client.

When using the destroy() method, it's important to handle the deletion of related objects correctly. By default, when you delete a parent object, any related child objects will also be deleted. This is known as "cascading deletion". Depending on your use case, this may not be the desired behavior.

Here are a few ways you can handle cascading deletion in Django REST Framework:

• Use models.SET_NULL or models.SET_DEFAULT on the ForeignKey fields, this way the related object will not be deleted but rather set to null or default value.
• Override the perform_destroy() method of the view, and handle the deletion of related objects explicitly.
• Use the django-softdelete library that provides a soft-delete feature for models, which allows you to mark an object as deleted, but not remove it from the database. This will keep any related objects intact.
• Set on_delete=models.PROTECT on ForeignKey fields, this will prevent the deletion of an object if it is still related to other objects

In any case, it's important to consider the potential impact of deleting objects and to handle related objects correctly to avoid data loss or integrity errors.

Batch Deletes

In Saving and Deleting Objects in Django Rest Framework (DRF), batch deletes can be implemented using the destroy method on a ViewSet. This method should be overridden to provide custom behavior for handling the deletion of multiple objects at once. To perform a batch delete, the client should send a DELETE request with a list of object IDs in the request body. The destroy method should then iterate through the list of IDs and delete the corresponding objects.

Additionally, it is a good practice to wrap the delete operations in the atomic transaction for Data Consistency.

You could also use the destroy() method in an APIView, you should ensure you got proper permissions to delete multiple rows and pass in the IDs to be deleted in the request data, or use the ids parameter in query_params. You can create an endpoint that accepts a list of object IDs in the request data, then use the queryset associated with the view to retrieve and delete the specified objects.

Here's an example of how you might create a batch_destroy endpoint in your views:

You can also use queryset.filter(id__in=ids).update(is_deleted=True) as an alternative to delete() if you're using the soft delete approach. Also, you need to add the endpoint to your urls.py file, to map the new endpoint to a URL.

It's important to be very careful when performing batch deletes, as it can have a significant impact on your data.

Recovery

In Saving and Deleting Objects in Django Rest Framework (DRF), the process of recovering a deleted resource typically involves creating a new endpoint or route that will handle the recovery logic. The endpoint should be accessible only to users with the proper permissions and should be able to handle the unique identifier of the resource to be recovered.

• One way to accomplish this is to create a new "recover" method on the ViewSet, which can be called when a PUT or PATCH request is sent to the endpoint. The recover method should take the ID of the resource to be recovered and update its "deleted" status to "False". The method should also handle any errors that may occur during the recovery process, such as if the resource is not found or if the user does not have permission to recover the resource.

• Another way is to use the soft-delete technique, Using this method you set a deleted flag on the model, rather than deleting it from the database, so it could be recovered later on. This flag could be set to False when calling the recovery endpoint, or when calling a custom recover manager method on the model. Here's an example of how you might implement resource recovery in a Django Rest Framework (DRF) ViewSet:

In this example, we've created a custom recover method on the ViewSet that takes in a request and the primary key of the resource to be recovered. It retrieves the instance of the model that corresponds to the given primary key, set the deleted attribute to False, and saves it. And then respond with a 204 NO_CONTENT status code.

You would also need to add the recover endpoint to your urls.py file and add permission checks so that only users with the proper permissions can recover resources.

This is just one example, there are many ways you could implement this, depending on your specific use case. But it gives you an idea of what a basic resource recovery endpoint in DRF might look like.