#15: stored function for cash-based stock replenishment transaction

brmbar3/brmbar/Shop.py

@@ -119,13 +119,17 @@ class Shop:
         #self.withdraw_credit(amount, userfrom)
 
     def buy_for_cash(self, item, amount = 1):
+        cost = self.db.execute_and_fetch(
+            "SELECT public.buy_for_cash(%s, %s, %s, %s, %s)",
+            [self.cash.id, item.id, amount, self.currency.id, item.name]
+        )[0]
         # Buy: Currency conversion from item currency to shop currency
-        (buy, sell) = item.currency.rates(self.currency)
+        #(buy, sell) = item.currency.rates(self.currency)
-        cost = amount * buy
+        #cost = amount * buy
 
-        transaction = self._transaction(description = "BrmBar stock replenishment of {}x {} for cash".format(amount, item.name))
+        #transaction = self._transaction(description = "BrmBar stock replenishment of {}x {} for cash".format(amount, item.name))
-        item.debit(transaction, amount, "Cash")
+        #item.debit(transaction, amount, "Cash")
-        self.cash.credit(transaction, cost, item.name)
+        #self.cash.credit(transaction, cost, item.name)
         self.db.commit()
 
         return cost

brmbar3/schema/0015-shop-buy-for-cash.sql

@@ -0,0 +1,82 @@
+--
+-- 0015-shop-buy-for-cash.sql
+--
+-- #15 - stored function for cash-based stock replenishment transaction
+--
+-- ISC License
+--
+-- Copyright 2023-2025 Brmlab, z.s.
+-- TMA <tma+hs@jikos.cz>
+--
+-- Permission to use, copy, modify, and/or distribute this software
+-- for any purpose with or without fee is hereby granted, provided
+-- that the above copyright notice and this permission notice appear
+-- in all copies.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+-- WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+-- WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+-- AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+-- CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+-- OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+-- NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+--
+
+-- To require fully-qualified names
+SELECT pg_catalog.set_config('search_path', '', false);
+
+DO $upgrade_block$
+BEGIN
+
+IF brmbar_privileged.has_exact_schema_version(9) THEN
+
+CREATE OR REPLACE FUNCTION public.buy_for_cash(
+	i_cash_account_id public.accounts.id%TYPE,
+	i_item_id public.accounts.id%TYPE,
+	i_amount INTEGER,
+	i_target_currency_id public.currencies.id%TYPE,
+	i_item_name TEXT
+) RETURNS NUMERIC
+LANGUAGE plpgsql
+AS $$
+DECLARE
+	v_buy_rate NUMERIC;
+	v_cost NUMERIC;
+	v_transaction_id public.transactions.id%TYPE;
+BEGIN
+	-- this could fail and it would generate exception in python
+	-- FIXME: convert v_buy_rate < 0 into python exception
+	v_buy_rate := public.find_buy_rate(i_item_id, i_target_currency_id);
+	-- this could fail and it would generate exception in python, even though it is not used
+	--v_sell_rate := public.find_sell_rate(i_item_id, i_target_currency_id);
+
+	-- Calculate cost and profit
+	v_cost := i_amount * v_buy_rate;
+
+	-- Create a new transaction
+	v_transaction_id := brmbar_privileged.create_transaction(NULL,
+		'BrmBar stock replenishment of ' || i_amount || 'x ' || i_item_name || ' for cash');
+
+	-- the item
+	INSERT INTO public.transaction_splits (transaction, side, account, amount, memo)
+	VALUES (i_transaction_id, 'debit', i_item_id, i_amount,
+	'Cash');
+
+	-- the cash
+	INSERT INTO public.transaction_splits (transaction, side, account, amount, memo)
+	VALUES (i_transaction_id, 'credit', i_cash_account_id, v_cost,
+	i_item_name);
+
+	-- Return the cost
+	RETURN v_cost;
+END;
+$$;
+
+PERFORM brmbar_privileged.upgrade_schema_version_to(10);
+END IF;
+
+END;
+$upgrade_block$;
+
+-- vim: set ft=plsql :