[Enhancement] POS

erpnext/controllers/accounts_controller.py

@@ -33,6 +33,7 @@ class AccountsController(TransactionBase):
 
 		if self.meta.get_field("currency"):
 			self.calculate_taxes_and_totals()
+
 			if not self.meta.get_field("is_return") or not self.is_return:
 				self.validate_value("base_grand_total", ">=", 0)
 
@@ -54,17 +55,19 @@ class AccountsController(TransactionBase):
 			if not self.get("__islocal"):
 				validate_recurring_document(self)
 				convert_to_recurring(self, self.get("posting_date") or self.get("transaction_date"))
-		
-		self.validate_paid_amount()
-	
+
+		if self.doctype == 'Purchase Invoice':
+			self.validate_paid_amount()
+
 	def validate_paid_amount(self):
 		if hasattr(self, "is_pos") or hasattr(self, "is_paid"):
 			is_paid = self.get("is_pos") or self.get("is_paid")
 			if cint(is_paid) == 1:
-				if flt(self.paid_amount) == 0:
+				if flt(self.paid_amount) == 0 and flt(self.outstanding_amount) > 0:
 					if self.cash_bank_account:
 						self.paid_amount = flt(flt(self.grand_total) - flt(self.write_off_amount), 
 							self.precision("paid_amount"))
+						self.base_paid_amount = flt(self.paid_amount * self.conversion_rate, self.precision("base_paid_amount"))
 					else:
 						# show message that the amount is not paid
 						self.paid_amount = 0
@@ -72,9 +75,6 @@ class AccountsController(TransactionBase):
 			else:
 				frappe.db.set(self,'paid_amount',0)
 
-			frappe.db.set(self, 'base_paid_amount',
-				flt(self.paid_amount*self.conversion_rate, self.precision("base_paid_amount")))
-
 	def on_update_after_submit(self):
 		if self.meta.get_field("is_recurring"):
 			validate_recurring_document(self)
@@ -510,7 +510,7 @@ class AccountsController(TransactionBase):
 							elif asset.status in ("Scrapped", "Cancelled", "Sold"):
 								frappe.throw(_("Row #{0}: Asset {1} cannot be submitted, it is already {2}")
 									.format(d.idx, d.asset, asset.status))
-						
+
 @frappe.whitelist()
 def get_tax_rate(account_head):
 	return frappe.db.get_value("Account", account_head, "tax_rate")

erpnext/controllers/taxes_and_totals.py

@@ -435,13 +435,39 @@ class calculate_taxes_and_totals(object):
 					- flt(self.doc.base_write_off_amount), self.doc.precision("grand_total"))
 
 		if self.doc.doctype == "Sales Invoice":
+			self.calculate_paid_amount()
 			self.doc.round_floats_in(self.doc, ["paid_amount"])
 			paid_amount = self.doc.paid_amount \
 				if self.doc.party_account_currency == self.doc.currency else self.doc.base_paid_amount
-			self.doc.outstanding_amount = flt(total_amount_to_pay - flt(paid_amount),
-				self.doc.precision("outstanding_amount"))
+
+			self.doc.outstanding_amount = 0
+			if total_amount_to_pay > paid_amount:
+				self.doc.outstanding_amount = flt(total_amount_to_pay - flt(paid_amount),
+					self.doc.precision("outstanding_amount"))
+			self.change_amount()
+
 		elif self.doc.doctype == "Purchase Invoice":
 			self.doc.outstanding_amount = flt(total_amount_to_pay, self.doc.precision("outstanding_amount"))
+		
+	def calculate_paid_amount(self):
+		paid_amount = base_paid_amount = 0.0
+		for payment in self.doc.get('payments'):
+			payment.base_amount = flt(payment.amount * self.doc.conversion_rate)
+			paid_amount += payment.amount
+			base_paid_amount += payment.base_amount
+
+		self.doc.paid_amount = flt(paid_amount, self.doc.precision("paid_amount"))
+		self.doc.base_paid_amount = flt(base_paid_amount, self.doc.precision("base_paid_amount"))
+
+	def change_amount(self):
+		change_amount = 0.0
+		if self.doc.paid_amount > self.doc.grand_total:
+			change_amount = flt(self.doc.paid_amount - self.doc.grand_total, 
+				self.doc.precision("change_amount"))
+
+		self.doc.change_amount = change_amount;
+		self.doc.base_change_amount = flt(change_amount * self.doc.conversion_rate, 
+			self.doc.precision("base_change_amount"))
 
 	def calculate_margin(self, item):
 		total_margin = 0.0