zoo/zoo/zoo_data/models.py

from operator import __add__, __or__

from django.db import models, connection
from django.db.models import F, Value
from django.db.models.query import QuerySet, Q
from django.core.exceptions import ValidationError
from django.utils.translation import ugettext_lazy as _
from django.contrib.postgres.fields import JSONField
from django.contrib.postgres.search import TrigramDistance


from .search import Unaccent, Lower, JSONTextRef
from zoo.zoo_meta.validators import schema_validator


class Transaction(models.Model):
    created = models.DateTimeField(
        auto_now_add=True,
        verbose_name=_('created'))
    meta = JSONField(
        verbose_name=_('meta'),
        blank=True,
        null=True)
    content = JSONField(
        verbose_name=_('content'),
        blank=True,
        null=True)

    def __unicode__(self):
        return unicode(self.id)

    class Meta:
        ordering = ('id',)
        verbose_name = _('transaction')
        verbose_name_plural = _('transactions')


class EntityQuerySet(QuerySet):
    def content_search(self, schema, limit=0.3, **kwargs):
        qs = self
        qs = qs.filter(schema=schema)
        filters = []
        connection.cursor().execute('SELECT SET_LIMIT(%s)', (limit,))
        for key, value in kwargs.iteritems():
            filters.append(Q(**{
                'content__' + key + '__unaccent__lower__trigram_similar':
                Lower(Unaccent(Value(value))),
            }))
        qs = qs.filter(reduce(__or__, filters))
        expressions = []
        ordering = []
        for key, value in kwargs.iteritems():
            ordering.append(Lower(Unaccent(JSONTextRef(F('content'), *key.split('__')))))
            expressions.append(TrigramDistance(
                Lower(Unaccent(JSONTextRef(F('content'), *key.split('__')))),
                Lower(Unaccent(Value(value)))))
        expression = reduce(__add__, expressions)
        qs = qs.annotate(similarity=expression / len(kwargs))
        qs = qs.order_by('similarity', *ordering)
        return qs


class CommonData(models.Model):
    def clean(self):
        if self.schema:
            try:
                schema_validator(self.schema.schema)(self.content)
            except ValidationError, e:
                raise ValidationError({'content': e})

    def save(self, *args, **kwargs):
        # ensure we have a strict serialization of transactions
        # move elsewhere later
        with connection.cursor() as cursor:
            cursor.execute('LOCK TABLE %s' % Transaction._meta.db_table)
            tr = Transaction.objects.create()
            if self.id:
                self.modified = tr
            else:
                self.created = tr
        return super(CommonData, self).save(*args, **kwargs)

    def __unicode__(self):
        return unicode(self.id)

    class Meta:
        abstract = True


class Entity(CommonData):
    schema = models.ForeignKey(
        'zoo_meta.EntitySchema',
        verbose_name=_('schema'))
    created = models.ForeignKey(
        Transaction,
        blank=True,
        null=True,
        verbose_name=_('created'),
        related_name='created_entities')
    modified = models.ForeignKey(
        Transaction,
        blank=True,
        null=True,
        verbose_name=_('modified'),
        related_name='modified_entities')
    deleted = models.ForeignKey(
        Transaction,
        verbose_name=_('deleted'),
        blank=True,
        null=True,
        related_name='deleted_entities')
    meta = JSONField(
        blank=True,
        null=True,
        verbose_name=_('meta'))
    content = JSONField(
        blank=True,
        null=False,
        verbose_name=_('content'))

    objects = EntityQuerySet.as_manager()

    class Meta:
        ordering = ('created',)
        verbose_name = _('entity')
        verbose_name_plural = _('entities')


class Relation(CommonData):
    schema = models.ForeignKey(
        'zoo_meta.RelationSchema',
        verbose_name=_('schema'))
    left = models.ForeignKey(
        'Entity',
        verbose_name=_('left'),
        related_name='left_relations')
    right = models.ForeignKey(
        'Entity',
        verbose_name=_('right'),
        related_name='right_relations')
    created = models.ForeignKey(
        Transaction,
        blank=True,
        null=True,
        verbose_name=_('created'),
        related_name='created_relations')
    modified = models.ForeignKey(
        Transaction,
        blank=True,
        null=True,
        verbose_name=_('modified'),
        related_name='modified_relations')
    deleted = models.ForeignKey(
        Transaction,
        verbose_name=_('deleted'),
        blank=True,
        null=True,
        related_name='deleted_relations')
    meta = JSONField(
        blank=True,
        null=True,
        verbose_name=_('meta'))
    content = JSONField(
        blank=True,
        null=False,
        verbose_name=_('content'))

    class Meta:
        ordering = ('created',)
        verbose_name = _('relation')
        verbose_name_plural = _('relations')


class Log(models.Model):
    entity = models.ForeignKey(
        'Entity',
        verbose_name=_('entity'))
    transaction = models.ForeignKey(
        'Transaction',
        verbose_name=_('transaction'))
    timestamp = models.DateTimeField(
        auto_now_add=True,
        db_index=True,
        verbose_name=_('timestamp'))
    content = JSONField(
        blank=True,
        null=True,
        verbose_name=_('content'))
    url = models.URLField(
        blank=True,
        null=True,
        verbose_name=_('url'))

    class Meta:
        ordering = ('timestamp',)
        verbose_name = _('log')
        verbose_name_plural = _('logs')