InvenTree/InvenTree/stock/models.py

from __future__ import unicode_literals
from django.utils.translation import ugettext as _
from django.db import models, transaction
from django.core.validators import MinValueValidator
from django.contrib.auth.models import User

from supplier.models import SupplierPart
from supplier.models import Customer
from part.models import Part
from InvenTree.models import InvenTreeTree

from datetime import datetime

from django.db.models.signals import pre_delete
from django.dispatch import receiver


class StockLocation(InvenTreeTree):
    """ Organization tree for StockItem objects
    A "StockLocation" can be considered a warehouse, or storage location
    Stock locations can be heirarchical as required
    """

    def get_absolute_url(self):
        return '/stock/location/{id}/'.format(id=self.id)

    @property
    def items(self):
        stock_list = self.stockitem_set.all()
        return stock_list


@receiver(pre_delete, sender=StockLocation, dispatch_uid='stocklocation_delete_log')
def before_delete_stock_location(sender, instance, using, **kwargs):

    # Update each part in the stock location
    for item in instance.items.all():
        # If this location has a parent, move the child stock items to the parent
        if instance.parent:
            item.location = instance.parent
            item.save()
        # No parent location? Delete the stock items
        else:
            item.delete()

    # Update each child category
    for child in instance.children.all():
        child.parent = instance.parent
        child.save()


class StockItem(models.Model):
    """
    A 'StockItem' instance represents a quantity of physical instances of a part.
    It may exist in a StockLocation, or as part of a sub-assembly installed into another StockItem
    StockItems may be tracked using batch or serial numbers.
    If a serial number is assigned, then StockItem cannot have a quantity other than 1
    """

    def get_absolute_url(self):
        return '/stock/item/{id}/'.format(id=self.id)

    # The 'master' copy of the part of which this stock item is an instance
    part = models.ForeignKey(Part, on_delete=models.CASCADE, related_name='locations')

    # The 'supplier part' used in this instance. May be null if no supplier parts are defined the master part
    supplier_part = models.ForeignKey(SupplierPart, blank=True, null=True, on_delete=models.SET_NULL)

    # Where the part is stored. If the part has been used to build another stock item, the location may not make sense
    location = models.ForeignKey(StockLocation, on_delete=models.DO_NOTHING,
                                 related_name='items', blank=True, null=True)

    # If this StockItem belongs to another StockItem (e.g. as part of a sub-assembly)
    belongs_to = models.ForeignKey('self', on_delete=models.DO_NOTHING,
                                   related_name='owned_parts', blank=True, null=True)

    # The StockItem may be assigned to a particular customer
    customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, related_name='stockitems', blank=True, null=True)

    # Optional serial number
    serial = models.PositiveIntegerField(blank=True, null=True)

    # Optional URL to link to external resource
    URL = models.URLField(max_length=125, blank=True)

    # Optional batch information
    batch = models.CharField(max_length=100, blank=True)

    # Quantity of this stock item. Value may be overridden by other settings
    quantity = models.PositiveIntegerField(validators=[MinValueValidator(0)])

    # Last time this item was updated (set automagically)
    updated = models.DateField(auto_now=True)

    # last time the stock was checked / counted
    stocktake_date = models.DateField(blank=True, null=True)

    stocktake_user = models.ForeignKey(User, on_delete=models.SET_NULL, blank=True, null=True)

    review_needed = models.BooleanField(default=False)

    # Stock status types
    ITEM_OK = 10
    ITEM_ATTENTION = 50
    ITEM_DAMAGED = 55
    ITEM_DESTROYED = 60

    ITEM_STATUS_CODES = {
        ITEM_OK: _("OK"),
        ITEM_ATTENTION: _("Attention needed"),
        ITEM_DAMAGED: _("Damaged"),
        ITEM_DESTROYED: _("Destroyed")
    }

    status = models.PositiveIntegerField(
        default=ITEM_OK,
        choices=ITEM_STATUS_CODES.items(),
        validators=[MinValueValidator(0)])

    notes = models.CharField(max_length=100, blank=True)

    # If stock item is incoming, an (optional) ETA field
    # expected_arrival = models.DateField(null=True, blank=True)

    infinite = models.BooleanField(default=False)

    @property
    def has_tracking_info(self):
        return self.tracking_info.all().count() > 0

    @transaction.atomic
    def stocktake(self, count, user):
        """ Perform item stocktake.
        When the quantity of an item is counted,
        record the date of stocktake
        """

        count = int(count)

        if count < 0 or self.infinite:
            return

        self.quantity = count
        self.stocktake_date = datetime.now().date()
        self.stocktake_user = user
        self.save()

    @transaction.atomic
    def add_stock(self, amount):
        """ Add items to stock
        This function can be called by initiating a ProjectRun,
        or by manually adding the items to the stock location
        """

        amount = int(amount)

        if self.infinite or amount == 0:
            return

        amount = int(amount)

        q = self.quantity + amount
        if q < 0:
            q = 0

        self.quantity = q
        self.save()

    @transaction.atomic
    def take_stock(self, amount):
        self.add_stock(-amount)

    def __str__(self):
        return "{n} x {part} @ {loc}".format(
            n=self.quantity,
            part=self.part.name,
            loc=self.location.name)

    @property
    def is_trackable(self):
        return self.part.trackable


class StockItemTracking(models.Model):
    """ Stock tracking entry
    """

    # Stock item
    item = models.ForeignKey(StockItem, on_delete=models.CASCADE,
                             related_name='tracking_info')

    # Date this entry was created (cannot be edited)
    date = models.DateField(auto_now_add=True, editable=False)

    # Short-form title for this tracking entry
    title = models.CharField(max_length=250)

    # Optional longer description
    description = models.CharField(max_length=1024, blank=True)

    # Which user created this tracking entry?
    user = models.ForeignKey(User, on_delete=models.SET_NULL, blank=True, null=True)

    # TODO
    # image = models.ImageField(upload_to=func, max_length=255, null=True, blank=True)

    # TODO
    # file = models.FileField()