Handful utils to work with raw queries in Django
Project description
PostgreSQL locks
Django already exposes row-level locks with QuerySet.select_for_update()
method.
What's missing is table-level and advisory locks:
from django_query_utils.postgres.locks import table_lock, LockMode
with table_lock("auth_user", "auth_group", mode=LockMode.Exclusive, timeout=10):
""" Perform some esclusive operations on locked tables """
# Set a lock for Django model tables
from django.contrib.auth import models
with table_lock.for_model(models.User, models.Group, **kwargs):
...
from django_query_utils.postgres.locks import advisory_lock
lock_id = 42
with advisory_lock(lock_id, using="default", nowait=True):
""" Perform some actions with locked resources """
# Create a more meaningful lock.
# Postgres spports either a single `bigint` or (`int`, `int`) pair as a lock_id.
# `advisory_lock` tries to convert any strings (or bigger ints) to postgres format
# either with hashing and bit shifts.
from django.db import transaction
from django.contrib.auth.models import User
user = User.objects.get(id=42)
with transaction.atomic(), advisory_lock("user:act", user.id, timeout=10):
""" Perform some actions with locked resources.
Timeout is only awailable within a transaction block. """
PostgreSQL full-text search support for django-filter
from django_query_utils.postgres.filters import FullTextSearchFilter
class MyFilterSet(django_filters.FilterSet):
search = FullTextSearchFilter(
vector=("field_1", "field__subfield"), # or `SearchVector` instance
search_type="phrase",
config="french",
)
With search_type="custom"
you may pass custom query expressions
class MyFilterSet(django_filters.FilterSet):
search = FullTextSearchFilter(
vector=("first_name", "last_name", "email"), # or `SearchVector` instance
search_type="custom",
)
qs = User.objects.all()
filters = MyFilterSet({"search": "(John | Mike | Dan) Doe"}, qs)
Raw Query wrappers:
from django_query_utils import Query, query_context
query = Query("select first_name, last_name from auth_user where email = %(email)s", {"email": "jdoe@example.com"})
with query_context(using="default") as c:
results = list(c.execute(query))
assert results == [{"first_name": "John", "last_name": "Doe"}]
Different result materializers:
from django_query_utils import PlainMaterializer, Query, query_context
query = Query(
"select first_name, last_name from auth_user where email = %(email)s",
{"email": "jdoe@example.com"},
materializer=PlainMaterializer(),
)
with query_context(using="default") as c:
results = list(c.execute(query))
assert results == [("John", "Doe")]
More sophisticated transformers to kwarg classes:
from dataclasses import dataclass
@dataclass
class MyUser:
first_name: str
last_name: str
with query_context() as c:
results = c.execute(query.as_type(MyUser))
assert list(results) == [MyUser(first_name="John", last_name="Doe")]
(PostgreSQL only) psycopg2.sql
query formatting support:
from psycopg2 import sql
raw_q = sql.SQL("select first_name, last_name from auth_user where email = {}")
query = Query(raw_q.format(sql.Literal("jdoe@example.com")))
...
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