add trade and position service

internal/database/portfolio.go

@@ -43,9 +43,9 @@ func GetTrades(db *sql.DB) ([]model.Trade, error) {
 }
 
 func GetPositions(db *sql.DB) ([]model.Position, error) {
-	rows, err := db.Query("SELECT company_id, symbol, shares, weight, CostBasis, currency_id, currency_code from position")
+	rows, err := db.Query("SELECT company_id, symbol, shares, weight, cost_basis, currency_id, currency_code from position")
 	if err != nil {
-		return nil, err
+		return []model.Position{}, err
 	}
 	defer rows.Close()
 
@@ -55,13 +55,13 @@ func GetPositions(db *sql.DB) ([]model.Position, error) {
 
 		err := rows.Scan(&t.CompanyID, &t.Symbol, &t.Shares, &t.Weight, &t.CostBasis, &t.CurrencyID, &t.CurrencyCode)
 		if err != nil {
-			return nil, err
+			return []model.Position{}, err
 		}
 
 		positions = append(positions, t)
 	}
 	if err = rows.Err(); err != nil {
-		return nil, err
+		return []model.Position{}, err
 	}
 
 	return positions, nil