Metadata-Version: 2.1
Name: django-bulk-sync
Version: 1.1.2
Summary: Combine bulk add, update, and delete into a single call.
Home-page: https://github.com/mathandpencil/django-bulk-sync
Author: Scott Stafford
Author-email: scott.stafford+bulksync@gmail.com
License: UNKNOWN
Description: # django-bulk-sync
        Combine bulk create, update, and delete into a single call.
        
        `django-bulk-sync` is a package for the Django ORM that combines bulk_create, bulk_update, and delete into a single method call to `bulk_sync`. 
        
        It manages all necessary creates, updates, and deletes with as few database calls as possible to maximize performance.
        
        ## Installation
        
        The package is available on pip as [django-bulk-sync][django-bulk-sync].  Run:
        
        `pip install django-bulk-sync`
        
        then import via:
        
        `from bulk_sync import bulk_sync`
        
        ## A Usage Scenario
        
        Companies have zero or more Employees. You want to efficiently sync the names of all employees for a single `Company` from an import from that company, but some are added, updated, or removed.  The simple approach is inefficient -- read the import line by line, and:
        
        For each of N records:
        
        - SELECT to check for the employee's existence
        - UPDATE if it exists, INSERT if it doesn't
        
        Then figure out some way to identify what was missing and delete it.  As is so often the case, the speed of this process is controlled mostly by the number of queries run, and here it is about two queries for every record, and so O(N).
        
        Instead, with `bulk_sync`, we can avoid the O(N) number of queries, and simplify the logic we have to write as well. 
        	
        ## Example Usage
        
        ```python
        from django.db.models import Q
        from bulk_sync import bulk_sync
        
        new_models = []
        for line in company_import_file:
        	# The `.id` (or `.pk`) field should not be set. Instead, `key_fields` 
        	# tells it how to match.
        	e = Employee(name=line['name'], phone_number=line['phone_number'], ...)
        	new_models.append(e)
        
        # `filters` controls the subset of objects considered when deciding to 
        # update or delete.
        filters = Q(company_id=501)  
        # `key_fields` matches an existing object if all `key_fields` are equal.
        key_fields = ('name', )  
        ret = bulk_sync(
                new_models=new_models,
                filters=filters,
                key_fields=key_fields)
        
        print("Results of bulk_sync: "
              "{created} created, {updated} updated, {deleted} deleted."
              		.format(**ret['stats']))
        ```
        
        Under the hood, it will atomically call `bulk_create`, `bulk_update`, and a single queryset `delete()` call, to correctly and efficiently update all fields of all employees for the filtered Company, using `name` to match properly. 
        
        ## Argument Reference
        
        `def bulk_sync(new_models, key_fields, filters, batch_size=None):`
        - `new_models`: An iterable of Django ORM `Model` objects that you want stored in the database. They may or may not have `id` set, but you should not have already called `save()` on them.
        - `key_fields`: Identifying attribute name(s) to match up `new_models` items with database rows.  If a foreign key is being used as a key field, be sure to pass the `fieldname_id` rather than the `fieldname`.
        - `filters`: Q() filters specifying the subset of the database to work in.
        - `batch_size`: passes through to Django `bulk_create.batch_size` and `bulk_update.batch_size`, and controls how many objects are created/updated per SQL query.
            """
        
Platform: UNKNOWN
Classifier: Programming Language :: Python :: 3
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Framework :: Django
Description-Content-Type: text/markdown
