[IMP] estate: SQL and Python constrains

-Added SQL's CHECK and UNIQUE constrains on given fields.
-CHECK: selling, offer, expected prices should be strictly positive.
-UNIQUE: property type and tag should be unique.
-odoo's @api. constrains on selling & expected price to  make sure that selling
 price does not fall more lower than 90% of expected price

estate/models/estate_property.py

@@ -1,4 +1,4 @@
-from dateutil.relativedelta import relativedelta
+from odoo.tools import float_compare
 from odoo import api,fields, models, exceptions
 
 #Class of EstateProperty to define fields of database table
@@ -9,7 +9,7 @@ class EstateProperty(models.Model):
     name = fields.Char(string='Name',required=True)
     description = fields.Text(string='Description')
     postcode = fields.Char(string='Postcode')
-    date_availability = fields.Date(string='Available From', copy=False, default=fields.Date.add(fields.Date.today()+ relativedelta(months=3)))
+    date_availability = fields.Date(string='Available From', copy=False, default=fields.Date.add(fields.Date.today(), months=3))
     expected_price = fields.Float(string='Expected Price', required=True)
     selling_price = fields.Float(string='Selling Price ', readonly=True, copy=False)
     bedrooms = fields.Integer(string='Bedrooms', default=2)
@@ -43,6 +43,11 @@ class EstateProperty(models.Model):
     offer_ids = fields.One2many('estate.property.offer','property_id',string='Offers') #One2Many field
     best_prices = fields.Float(string='Best Offer',compute='_compute_best_offer')
 
+    _sql_constraints = [
+        ('check_expected_price','CHECK(expected_price > 0)','Expected Price must be positive'),
+        ('check_selling_price','CHECK(selling_price > 0)','Selling Price must be positive'),
+    ] 
+
     #Function of computing total area
     @api.depends('living_area','garden_area')
     def _compute_total_area(self):
@@ -83,3 +88,12 @@ def action_to_cancel_property(self):
             record.state = 'cancelled'
         return True
 
+    #constrain of selling price not fall more lower than 90% expected price
+    @api.constrains('selling_price','expected_price')
+    def _check_selling_price(self):
+        for record in self:
+            threshold = record.expected_price * 0.90
+            if float_compare(threshold,record.selling_price,2) == 1:
+                raise exceptions.ValidationError("The selling price must be at least 90% of the expected price!You must reduce the expected price if you want to accept this offer.")
+
+

estate/models/estate_property_offer.py

@@ -15,7 +15,14 @@ class EstatePropertyOffer(models.Model):
     partner_id = fields.Many2one("res.partner",string="Partner")
     property_id = fields.Many2one("estate.property",string="Property")
     validate = fields.Integer(string="Validity(days)",default=7)
-    date_deadline = fields.Date(string="Deadline",default=fields.Date.today(),compute="_compute_deadline",inverse="_update_validity")
+    date_deadline = fields.Date(string="Deadline",
+                default=fields.Date.today(),
+                compute="_compute_deadline",
+                inverse="_update_validity")
+
+    _sql_constraints = [
+        ('check_price','CHECK(price > 0)','Offer Price must be positive'),
+    ] 
 
     #Function of implementing comptue field and inverse function on validity days and date dadeline
     @api.depends("validate","create_date")
@@ -36,7 +43,7 @@ def _update_validity(self):
     #Function to perform action when offer accpeted
     def action_accept(self):
         for record in self:
-            if record.property_id.selling_price and (record.status == 'accepted' or record.status == 'refused'):
+            if record.status == 'accepted':
                 raise exceptions.UserError("This property has already accepted offer!")
 
             record.property_id.selling_price = record.price

estate/models/estate_property_tags.py

@@ -5,4 +5,7 @@ class EstatePropertyTyags(models.Model):
     _description = "Property Tags"
 
     name = fields.Char(string="Name", required=True)
-
+
+    _sql_constraints = [
+        ('name_uniq', 'unique (name)', "Tag name already exists!"),
+    ]

estate/models/estate_property_type.py

@@ -5,4 +5,7 @@ class EstatePropertyType(models.Model):
     _description =  "Property Types"
 
     name = fields.Char(string="Name", required=True)
-
+
+    _sql_constraints = [
+        ('name_uniq', 'unique (name)', "Type name already exists!"),
+    ]