如何计算我定义的变量的总和?
我有:
product_sale.rb
def totalprice
price*quantity
end
视图
%h1 Listing Product Sales
%table
%thead
%tr
%th Product name
%th Price
%th Quantity
%th Total price
%tbody
- @product_sales.each do |product_sale|
%tr
%td= product_sale.product_name
%td= product_sale.price
%td= product_sale.quantity
%td= product_sale.totalprice
%br
%h1
Total sum to be paid:
= Product_sale.sum(:totalprice)
= Product_sale.sum(:totalprice)
不起作用。我怎么计算呢?
答案 0 :(得分:0)
NavigationView navigationView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}
@Override
public boolean onNavigationItemSelected(MenuItem item) {
//here will scroll to top
((NavigationMenuView)navigationView.getChildAt(0)).smoothScrollToPosition(0);
return true;
}
答案 1 :(得分:0)
@product_sales.sum('price * quantity') # single query, efficient
P.S。该类的正确名称是snakecased ProductSale
答案 2 :(得分:0)
@product_sales.sum(&:totalprice)
我认为这应该适用于您只选择所选产品销售总价的
答案 3 :(得分:0)
@product_sales.sum('price * quantity')
答案 4 :(得分:0)
对我来说最好的解决方案是Max:
控制器索引视图:library(ggplot2)
ggplot(df_clean, aes(x = Factor, y = measure, fill = Factor)) +
geom_bar(stat = "identity") +
geom_errorbar(aes(ymin = measure - SD, ymax = measure + SD)) +
facet_wrap(~ measure_letter)
查看:@some_total = @product_sales.map(&:totalprice).sum