Fix holding avg cost calculation

app/models/account/holding.rb

@@ -26,8 +26,12 @@ def weight
 
   # Basic approximation of cost-basis
   def avg_cost
-    avg_cost = account.holdings.for(security).where(currency: currency).where("date <= ?", date).average(:price)
-    Money.new(avg_cost, currency)
+    avg_cost = account.entries.account_trades
+                  .joins("INNER JOIN account_trades ON account_trades.id = account_entries.entryable_id")
+                  .where("account_trades.security_id = ? AND account_trades.qty > 0 AND account_entries.date <= ?", security.id, date)
+                  .average(:price)
+
+    Money.new(avg_cost || price, currency)
   end
 
   def trend

app/views/shared/_money_field.html.erb

@@ -36,7 +36,6 @@
         step: currency.step,
         data: {
           "money-field-target": "amount",
-          action: "change->money-field#handleAmountChange",
           "auto-submit-form-target": ("auto" if options[:auto_submit])
         }.compact,
         required: options[:required] %>

test/models/account/holding_test.rb

@@ -20,11 +20,20 @@ class Account::HoldingTest < ActiveSupport::TestCase
   end
 
   test "calculates simple average cost basis" do
+    create_trade(@amzn.security, account: @account, qty: 10, price: 212.00, date: 1.day.ago.to_date)
+    create_trade(@amzn.security, account: @account, qty: 15, price: 216.00, date: Date.current)
+
+    create_trade(@nvda.security, account: @account, qty: 5, price: 128.00, date: 1.day.ago.to_date)
+    create_trade(@nvda.security, account: @account, qty: 30, price: 124.00, date: Date.current)
+
     assert_equal Money.new((212.0 + 216.0) / 2), @amzn.avg_cost
     assert_equal Money.new((128.0 + 124.0) / 2), @nvda.avg_cost
   end
 
   test "calculates total return trend" do
+    @amzn.stubs(:avg_cost).returns(Money.new(214.00))
+    @nvda.stubs(:avg_cost).returns(Money.new(126.00))
+
     # Gained $30, or 0.93%
     assert_equal Money.new(30), @amzn.trend.value
     assert_in_delta 0.9, @amzn.trend.percent, 0.001