from django.dispatch import receiver
from django.db.models.signals import post_save, m2m_changed
from django.db.models import Value, TextField
from django.contrib.postgres.search import SearchVector
from django.db import transaction
from blog.models import BaseModel, Tag
import operator
from functools import reduce
@receiver(post_save)
def on_save(sender, **kwargs):
if not issubclass(sender, BaseModel):
return
transaction.on_commit(make_updater(kwargs["instance"]))
@receiver(m2m_changed)
def on_m2m_changed(sender, **kwargs):
instance = kwargs["instance"]
model = kwargs["model"]
if model is Tag:
transaction.on_commit(make_updater(instance))
elif isinstance(instance, Tag):
for obj in model.objects.filter(pk__in=kwargs["pk_set"]):
transaction.on_commit(make_updater(obj))
def make_updater(instance):
components = instance.index_components()
pk = instance.pk
def on_commit():
search_vectors = []
for weight, text in list(components.items()):
search_vectors.append(
SearchVector(Value(text, output_field=TextField()), weight=weight)
)
instance.__class__.objects.filter(pk=pk).update(
search_document=reduce(operator.add, search_vectors)
)
return on_commit
