mirror of
https://github.com/carrotquest/django-clickhouse.git
synced 2025-10-26 05:31:31 +03:00
66 lines
3.1 KiB
Markdown
66 lines
3.1 KiB
Markdown
# Making queries
|
|
|
|
QuerySet system used by this library looks very similar to django, but it is implemented separately.
|
|
You can read reasons for this design [here](motivation.md#separate-from-django-database-setting-queryset-and-migration-system).
|
|
|
|
## Usage
|
|
Library query system extends [infi.clickhouse-orm QuerySet system](https://github.com/Infinidat/infi.clickhouse_orm/blob/develop/docs/querysets.md) and supports all it features.
|
|
In most cases you have no need to create querysets explicitly - just use `objects` attribute or `objects_in(db)` method of `ClickHouseModel`.
|
|
At the same time `django-clickhouse` adds some extra features to `QuerySet` and `AggregateQuerySet`.
|
|
They are available if your model inherits `django_clickhouse.clickhouse_models.ClickHouseModel`.
|
|
|
|
## Extra features
|
|
### Django-like routing system
|
|
There's no need to set database object explicitly with `objects_in(...)` method, as original QuerySet expects.
|
|
Database is determined based on library configuration and [router](routing.md#router) used.
|
|
|
|
If you want to set database explicitly you can use any of approaches:
|
|
* [infi approach](https://github.com/Infinidat/infi.clickhouse_orm/blob/develop/docs/querysets.md#querysets)
|
|
* Django like `QuerySet.using(db_alias)` method
|
|
|
|
Example:
|
|
```python
|
|
from django_clickhouse.database import connections
|
|
from my_app.clickhouse_models import ClickHouseUser
|
|
|
|
# This query will choose database using current router.
|
|
# By default django_clickhouse.routers.DefaultRouter is used.
|
|
# It gets one random database, from ClickHouseUser.read_db_aliases for read queries
|
|
ClickHouseUser.objects.filter(id__in=[1,2,3]).count()
|
|
|
|
# These queries do the same thing, using 'secondary' connection from CLICKHOUSE_DATABASES setting
|
|
ClickHouseUser.objects_in(connections['secondary']).filter(id__in=[1,2,3]).count()
|
|
ClickHouseUser.objects.filter(id__in=[1,2,3]).using('secondary').count()
|
|
|
|
# You can get database to use with get_database(for_write: bool = False) method
|
|
# Note that it if you have multiple database in model settings,
|
|
# DefaultRouter can return any of them each time function is called, function is stateless
|
|
ClickHouseUser.objects.get_database(for_write=False)
|
|
```
|
|
|
|
### QuerySet create methods
|
|
This library adds methods to add objects like django does without direct Database object usage.
|
|
|
|
Example:
|
|
```python
|
|
from datetime import date
|
|
from my_app.clickhouse_models import ClickHouseUser
|
|
|
|
# This queries will choose database using current router.
|
|
# By default django_clickhouse.routers.DefaultRouter is used.
|
|
# It gets one random database, from ClickHouseUser.write_db_aliases for write queries
|
|
# You can set database explicitly with using(...) or objects_in(...) methods
|
|
instance = ClickHouseUser.objects.create(id=1, first_name='Alice', visits=1, birthday=date(2003, 6, 1))
|
|
objs = ClickHouseUser.objects.bulk_create([
|
|
ClickHouseUser(id=2, first_name='Bob', visits=2, birthday=date(2001, 5, 1)),
|
|
ClickHouseUser(id=3, first_name='Jhon', visits=3, birthday=date(2002, 7, 11))
|
|
], batch_size=10)
|
|
```
|
|
|
|
### Getting all objects
|
|
`QuerySet.all()` method returns copy of current QuerySet:
|
|
```python
|
|
from my_app.clickhouse_models import ClickHouseUser
|
|
|
|
qs = ClickHouseUser.objects.all()
|
|
``` |