Create the Asset Database (#363)

assets/models.py

@@ -0,0 +1,141 @@
+import re
+from django.core.exceptions import ValidationError
+from django.db import models, connection
+from django.urls import reverse
+
+
+class AssetCategory(models.Model):
+    class Meta:
+        verbose_name = 'Asset Category'
+        verbose_name_plural = 'Asset Categories'
+
+    name = models.CharField(max_length=80)
+
+    def __str__(self):
+        return self.name
+
+
+class AssetStatus(models.Model):
+    class Meta:
+        verbose_name = 'Asset Status'
+        verbose_name_plural = 'Asset Statuses'
+
+    name = models.CharField(max_length=80)
+    should_show = models.BooleanField(default=True, help_text="Should this be shown by default in the asset list.")
+
+    def __str__(self):
+        return self.name
+
+
+class Supplier(models.Model):
+    name = models.CharField(max_length=80)
+
+    class Meta:
+        permissions = (
+            ('view_supplier', 'Can view a supplier'),
+        )
+
+    def get_absolute_url(self):
+        return reverse('supplier_list')
+
+    def __str__(self):
+        return self.name
+
+
+class Connector(models.Model):
+    description = models.CharField(max_length=80)
+    current_rating = models.DecimalField(decimal_places=2, max_digits=10, help_text='Amps')
+    voltage_rating = models.IntegerField(help_text='Volts')
+    num_pins = models.IntegerField(blank=True, null=True)
+
+    def __str__(self):
+        return self.description
+
+
+class Asset(models.Model):
+    class Meta:
+        ordering = ['asset_id']
+        permissions = (
+            ('asset_finance', 'Can see financial data for assets'),
+            ('view_asset', 'Can view an asset')
+        )
+
+    parent = models.ForeignKey(to='self', related_name='asset_parent', blank=True, null=True, on_delete=models.SET_NULL)
+    asset_id = models.CharField(max_length=10, unique=True)
+    description = models.CharField(max_length=120)
+    category = models.ForeignKey(to=AssetCategory, on_delete=models.CASCADE)
+    status = models.ForeignKey(to=AssetStatus, on_delete=models.CASCADE)
+    serial_number = models.CharField(max_length=150, blank=True)
+    purchased_from = models.ForeignKey(to=Supplier, on_delete=models.CASCADE, blank=True, null=True)
+    date_acquired = models.DateField()
+    date_sold = models.DateField(blank=True, null=True)
+    purchase_price = models.DecimalField(blank=True, null=True, decimal_places=2, max_digits=10)
+    salvage_value = models.DecimalField(blank=True, null=True, decimal_places=2, max_digits=10)
+    comments = models.TextField(blank=True)
+    next_sched_maint = models.DateField(blank=True, null=True)
+
+    # Cable assets
+    is_cable = models.BooleanField(default=False)
+    plug = models.ForeignKey(Connector, on_delete=models.SET_NULL, related_name='plug', blank=True, null=True)
+    socket = models.ForeignKey(Connector, on_delete=models.SET_NULL, related_name='socket', blank=True, null=True)
+    length = models.DecimalField(decimal_places=1, max_digits=10, blank=True, null=True, help_text='m')
+    csa = models.DecimalField(decimal_places=2, max_digits=10, blank=True, null=True, help_text='mm^2')
+    circuits = models.IntegerField(blank=True, null=True)
+    cores = models.IntegerField(blank=True, null=True)
+
+    def get_available_asset_id():
+        sql = """
+        SELECT MIN(CAST(a.asset_id AS int))+1
+        FROM assets_asset a
+        LEFT OUTER JOIN assets_asset b ON
+            (CAST(a.asset_id AS int) + 1 = CAST(b.asset_id AS int))
+        WHERE b.asset_id IS NULL AND CAST(a.asset_id AS int) >= %s;
+        """
+        with connection.cursor() as cursor:
+            cursor.execute(sql, [9000])
+            row = cursor.fetchone()
+            if row[0] is None:
+                return 9000
+            else:
+                return row[0]
+
+    def get_absolute_url(self):
+        return reverse('asset_detail', kwargs={'pk': self.asset_id})
+
+    def __str__(self):
+        out = str(self.asset_id) + ' - ' + self.description
+        if self.is_cable:
+            out += '{} - {}m - {}'.format(self.plug, self.length, self.socket)
+        return out
+
+    def clean(self):
+        errdict = {}
+        if self.date_sold and self.date_acquired > self.date_sold:
+            errdict["date_sold"] = ["Cannot sell an item before it is acquired"]
+
+        self.asset_id = self.asset_id.upper()
+        if re.search("^[a-zA-Z0-9]+$", self.asset_id) is None:
+                errdict["asset_id"] = ["An Asset ID can only consist of letters and numbers"]
+
+        if self.purchase_price and self.purchase_price < 0:
+            errdict["purchase_price"] = ["A price cannot be negative"]
+
+        if self.salvage_value and self.salvage_value < 0:
+            errdict["salvage_value"] = ["A price cannot be negative"]
+
+        if self.is_cable:
+            if not self.length or self.length <= 0:
+                errdict["length"] = ["The length of a cable must be more than 0"]
+            if not self.csa or self.csa <= 0:
+                errdict["csa"] = ["The CSA of a cable must be more than 0"]
+            if not self.circuits or self.circuits <= 0:
+                errdict["circuits"] = ["There must be at least one circuit in a cable"]
+            if not self.cores or self.cores <= 0:
+                errdict["cores"] = ["There must be at least one core in a cable"]
+            if self.socket is None:
+                errdict["socket"] = ["A cable must have a socket"]
+            if self.plug is None:
+                errdict["plug"] = ["A cable must have a plug"]
+
+        if errdict != {}:  # If there was an error when validation
+            raise ValidationError(errdict)