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https://github.com/draup/draup_django

Delete functionality for normalised models
https://github.com/draup/draup_django

cascade delete django django-framework foreign-keys normalised-models relational-databases

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Delete functionality for normalised models

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# draup_django

[![Downloads](https://pepy.tech/badge/draup-django)](https://pepy.tech/project/draup-django)

### Delete, Update functionality for normalised models

## Use-Case :

* `Draup Django` provide
stateful delete, update functionality at ORM(object relational mapping)level.

## Table of Content :

* [Stateful Delete/Update](#stateful)
* [Get Affected Objects](#get-affected-objects)
* [Delete Object](#delete-object)
* [Update Object](#update-object)
* [Installation](#installation)

## Stateful Delete/Update
* Below are functions inorder to get the stateful delete/update

### Get Affected Objects
* List out all dependent objects(Prompt-Messages).
* `getAffectedObjects` takes input dict with id as key and reference of model.

```
Sample Input : ({'id':1},model_reference)
Output : Error_list(list),prompt messages(list)
```

### Delete Object
* Delete object with all the dependent objects.
* `deleteObject` takes input dict with id and force_delete as key and reference of model.

```
Sample Input : ({'id':1,'force_delete':True},model_reference)
Output : Error_list(list)
```

### Update Object
* Transferring Object dependencies from one object to another object.
* `updateObjectDependencies` takes input source,destination objects.

```
Sample Input : (source,destination)
Output : Error_list(list)
```

## Installation
* Use Pip to install the module

```
pip install draup-django
```

## Usage :
* Sample model :

class parent(models.Model):
name = models.CharField(max_length=100)

class child(models.Model):
parent = models.ForeignKey(parent, on_delete=models.CASCADE)
name = models.CharField(max_length=100)

* Parent Table :

| id | Name |
| ------ | --------- |
| 1 | Alice |
| 2 | Tom |

* Child Table :

| id | Name | parent_id |
| ----------- | --------- |-------------- |
| 1 | Bob | 1 |
| 2 | Jack | 2 |


* Code :

from draup_django import utility
m = models.parent

"""
Get Prompt Message
"""

error_list,prompt_message = utility.getAffectedObjects({'id':1},m)

"""
Deletion with all dependent objects
"""
error_list = utility.deleteObject({'id':1,'force_delete':True},m)

"""
Transferring Object dependencies
"""

source = m.objects.filter(id=1).first()
destination = m.objects.filter(id=2).first()
error_list = utility.updateObjectDependencies(source,destination)

* Output :
Prompt Message of `getAffectedObjects` function

[{'message': 'This object has been used in child 1 times.', 'model_name': 'child', 'Parent models': '', 'count': 1}]

* **Note** :
- Every function returns the error_list, and hence only the operation is successful only if it is empty.
- According to above Child/Parent Table `updateObjectDependencies` function will transafer object dependency from `id:1` to `id:2` so parent_id of `Bob` will become `2`.

- Updated Child Table:

| id | Name | parent_id |
| ----------- | --------- |-------------- |
| 1 | Bob | 2 |
| 2 | Jack | 2 |

## Limitation :
* `updateObjectDependencies` will not work in case of unique constraint,one to one field in model.
* Please feel free to share your thoughts and feedback at info@draup.com .

## About Draup :

[Draup](https://draup.com) is an enterprise decision-making platform for global CXO leaders in sales and talent domains. Draup combines Artificial Intelligence with human curation to help organizations make data-driven strategic decisions. The platform is powered by machine- generated models, which are augmented by a team of analysts adding their learning-based insights to provide a 360-degree transactable view of their sales and talent ecosystem. We work on cutting edge technolgies and run highly complex algorithms on huge volumes of data. We also rely on open-sourcing which equips us with the right tools which allows us to find truly unique and innovate solutions to several problems.