django-raw-sugar 0.1.18

Turns your raw sql into a QuerySet

django-raw-sugar

Turns your raw sql into a QuerySet.

Installation

Install using pip...

pip install django-raw-sugar

How to use

Basic usage

Attach RawManager instance to your model. Then use it's .from_raw() method.

RawManager.from_raw(raw_query=None, params=None, translations=None, null_fields=None, db_table=None)

You should provide either raw_query or db_table (but not both).

# models.py
from django.db import models
from raw_sugar import RawManager

class MySimpleModel(models.Model):
    name = models.TextField()
    number = models.IntegerField()
    source = models.ForeignKey(AnotherSimpleModel, models.DO_NOTHING)

    objects = RawManager()

# some other file
from .models import MySimpleModel

queryset = MySimpleModel.objects.from_raw(
    'SELECT Null as id, "my str" as name, 111 as number, Null as source_id')

The result of your raw sql must contain all the fields that are present in target model, including primary key and foreign keys. If you know your raw sql lacks some fields, you can provide the null_fields argument instead of modifying your query:

queryset = MySimpleModel.objects.from_raw(
    'SELECT "my str" as name, 111 as number', null_fields=['id', 'source_id'])

The resulting queryset is a regular models.QuerySet instance, and can be handled accordingly:

queryset = queryset.filter(number__gte=10)\
    .exclude(number__gte=1000)\
    .filter(name__contains='s')\
    .order_by('number')\
    .select_related('source')
print(queryset[0].name) # "my str"

Passing parameters

If you need to perform parameterized queries, you can use the params argument:

queryset = MySimpleModel.objects.from_raw(
    'SELECT "%s" as name, 111 as number', 
    params=['my str'],
    null_fields=['id', 'source_id'])

If you want to pass params deferred, you can use the with_params method:

queryset = MySimpleModel.objects.from_raw(
    'SELECT "%s" as name, 111 as number', 
    null_fields=['id', 'source_id'])
queryset = queryset.with_params('my str')

Using transtalions

If the field names of queried table differ from the model field names, you can map fields by using the translations argument:

queryset = MySimpleModel.objects.from_raw(
    'SELECT "%s" as name, 111 as inner_number', 
    params=['my str'],
    translations={'inner_number': 'number'},
    null_fields=['id', 'source_id'])

Pre defined source raw sql

You can define a model manager that uses your raw sql as query source by default. You can do this by passing a from_raw argument to RawManager, or by using the raw_manager decorator to method that returns a FromRaw instance:

from django.db import models
from raw_sugar import raw_manager, RawManager, FromRaw

class MySimpleModel(models.model):
    name = models.TextField()
    number = models.IntegerField()
    source = models.ForeignKey(AnotherSimpleModel, models.DO_NOTHING)

    my_raw_manager = RawManager(FromRaw('SELECT "my str" as name, 111 as number',
                                        null_fields=['id', 'source_id']))

    @raw_manager
    def my_raw_manager_2(cls):
        return FromRaw('SELECT "my str" as name, 111 as number',
                       null_fields=['id', 'source_id'])

    @raw_manager(is_callable=True)
    def my_callable_raw_manager(cls, name=""):
        return FromRaw('SELECT %s as name, 111 as number',
                       null_fields=['id', 'source_id'],
                       params=[name])

# some other file
from .models import MySimpleModel

queryset = MySimpleModel.my_raw_source.all()
queryset = MySimpleModel.my_raw_source_2.all()
queryset = MySimpleModel.my_callable_raw_source('my str').all()

print(queryset[0].name) # "my str"

The FromRaw class accepts all the arguments as the RawManager.from_raw: FromRaw(raw_query=None, params=None, translations=None, null_fields=None, db_table=None)

When you use the raw_manager decorator, the parameters you pass to with_params method will be passed into the decorated method, not into your raw. If you need this behavour, you can do it manually:

@raw_manager(is_callable=True)
def my_callable_raw_manager(cls, *args):
    assert len(args) == 2
    return FromRaw('SELECT %s as name, %s as number', null_fields=['id', 'source_id'], params=args)

Querying views / table functions

If you have a sql view or a sql table function in your database and want to query it, instead of passing sql like SELECT * from my_view you can use the db_table argument:

queryset = MySimpleModel.objects.from_raw(db_table='my_view')
queryset = MySimpleModel.objects.from_raw(db_table='my_func(%s, %s)', params=['param', 1])
queryset = MySimpleModel.objects.from_raw(db_table='my_func(%s, %s)').with_params('param', 1)

Use a QuerySet as a source

You can use a QuerySet instance as a source instead of raw sql by returning a FromQuerySet instance from decorated manager method:

class MySimpleModel(models.Model):
    name = models.TextField()
    number = models.IntegerField()
    source = models.ForeignKey(
        AnotherSimpleModel, models.DO_NOTHING, null=True)

    @raw_manager
    def my_qs_manager(cls):
        return FromQuerySet(
            cls.objects.values('source')\
                .annotate(_number=models.Sum('number')),
            translations={'_number': 'number'})

The FromQuerySet class accepts only a QuerySet and translations:

FromQuerySet(queryset, translations=None)

If the provided QuerySet lacks some fields, the Null will be returned. You don't need to specify null_fields as you would with the FromRaw.

Differences with Manager.raw()

Pros:

• The result of executing of your raw sql is a QuerySet (!!!), and can filter, order, annotate, union, etc. it.

Cons:

• The result of your FromRaw must contain all fields of target model, including primary and foreign keys. If you omit any, you get an OperationalError('no such column: ...') exception.
• If you don't provide some fields in source QuerySet when use the FromQuerySet, this fields are filled with Null, and can not be loaded on demand. The Django's RawQuerySet allows it.