避免在多(9)个条件下使用过多的if、else if语句

Question

我的if else语句有9个条件，我在想有没有其他的替代方案可以让代码变得简洁干净。所有9个条件都为asp.net mvc视图执行不同的计算。我已经包括了代码和一个图像，其中显示了一些条件的视图，希望它有意义，我正在寻找任何更好的和健壮的解决方案来解决这种情况。谢谢

//Condition 1
//when no selection is made for the 2 dropdownlist (garages & helmets)
if (formvalues["helmets"] == "" && formvalues["garages"] == "")
{
    ViewBag.hideHelmet = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedHelmets = 1;//
    ViewBag.SelectedGarages = 1;//
    ViewBag.TotalHelmets = 1;
    ViewBag.TotalGarages = 1;
    ViewBag.TotalAmount = 1;
    ViewBag.TotalAmount =  trackEventCost.UnitCost;
}
//Condition 2
//When garages are selected from dropdown & helmets are not selected
else if ((formvalues["helmets"] == "") && (Convert.ToInt32(formvalues["garages"]) > 0))
{
    ViewBag.hideHelmet = 0;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedHelmets = 1;
    ViewBag.SelectedGarages = Convert.ToInt32(formvalues["garages"]);
    ViewBag.TotalHelmets = 1;
    ViewBag.TotalGarages = Convert.ToInt32(formvalues["garages"]) * getGarages.UnitCost;
    ViewBag.TotalAmount = ViewBag.TotalGarages + trackEventCost.UnitCost;
}
//Condition 3
//When helmets are selected from dropdown & garages are not selected
else if ((formvalues["garages"] == "") && (Convert.ToInt32(formvalues["helmets"]) > 0))
{
    ViewBag.hideHelmet = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 0;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedGarages = 1;
    ViewBag.SelectedHelmets = Convert.ToInt32(formvalues["helmets"]);
    ViewBag.TotalGarages = 1;
    ViewBag.TotalHelmets = Convert.ToInt32(formvalues["helmets"]) * getGarages.UnitCost;
    ViewBag.TotalAmount = ViewBag.TotalHelmets + trackEventCost.UnitCost;
}
//Condition 4
//When garages are not selected from dropdown & helmets dropdownlist is hidden on the view due to unavailablity of helmets for that event
else if (formvalues["garages"] == "" && (formvalues["helmets"] == null))
{
    ViewBag.hideHelmet = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.TotalAmount = trackEventCost.UnitCost;
}
//Condition 5
//When helmets are not selected from dropdown & garages dropdownlist is hidden on the view due to unavailablity of garages for that event
else if ((formvalues["garages"] == null) && (formvalues["helmets"] == ""))
{
    ViewBag.hideHelmet = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedHelmets = 1;
    ViewBag.TotalAmount = trackEventCost.UnitCost;
}
//Condition 6
//When both helmets and garages dropdown list is not displayed on the view as they are not present in the database
else if (formvalues["helmets"] == null && formvalues["garages"] == null)
{
    ViewBag.SelectedHelmets = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedGarages = 1;//for jquery, This value is passed to jquery script which then decides which field to hide/show
    ViewBag.TotalHelmets = 1;
    ViewBag.TotalGarages = 1;
    ViewBag.hideHelmet = 1;
    ViewBag.hideGarages = 1;
    ViewBag.TotalAmount = trackEventCost.UnitCost;
}
//Condition 7
//When garages are selected from dropdown & helmets dropdownlist is hidden on the view due to unavailablity of helmets for that event
else if (formvalues["helmets"] == null && Convert.ToInt32(formvalues["garages"]) > 0)
{
    ViewBag.hideHelmet = 0; //for jquery , This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 1; //for jquery , This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedGarages = Convert.ToInt32(formvalues["garages"]);
    ViewBag.TotalGarages = Convert.ToInt32(formvalues["garages"]) * getGarages.UnitCost;
    ViewBag.TotalAmount = ViewBag.TotalGarages + trackEventCost.UnitCost;
}
//Condition 8
//When helmets are selected from dropdown & garages dropdownlist is hidden on the view due to unavailablity of garages for that event
else if (Convert.ToInt32(formvalues["helmets"]) > 0 && formvalues["garages"] == null)
{
    ViewBag.hideHelmet = 1; //for jquery , This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 0; //for jquery , This value is passed to jquery script which then decides which field to hide/show
    ViewBag.TotalHelmets = Convert.ToInt32(formvalues["helmets"]) * getHelmets.UnitCost;
    ViewBag.TotalAmount = ViewBag.TotalHelmets + trackEventCost.UnitCost;
}
//Condition 9
//When garages and helmet both dropdown are selected
 else
{
    ViewBag.hideHelmet = 0;//for jquery , This value is passed to jquery script which then decides which field to hide/show
    ViewBag.hideGarages = 0;//for jquery , This value is passed to jquery script which then decides which field to hide/show
    ViewBag.SelectedHelmets = Convert.ToInt32(formvalues["helmets"]);
    ViewBag.SelectedGarages = Convert.ToInt32(formvalues["garages"]);
    ViewBag.TotalHelmets = Convert.ToInt32(formvalues["helmets"]) * getHelmets.UnitCost;
    ViewBag.TotalGarages = Convert.ToInt32(formvalues["garages"]) * getGarages.UnitCost;
    ViewBag.TotalAmount = ViewBag.TotalHelmets + ViewBag.TotalGarages + trackEventCost.UnitCost;
}

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Answer 1

首先，将表单值的提取移到方法的开头，例如：

int? helmets = formvalues["helmets"] == null ?
  null : Convert.ToInt32(formvalues["helmets"];
int? garages = formvalues["garages"] == null ?
  null : Convert.ToInt32(formvalues["garages"];

然后，您可能可以非常容易地设置属性，而无需任何ifs/else ifs，例如：

ViewBag.hideHelmet = helmets;
// or
someOtherProperty = helmets == null ? ... : ...

更新(关于您的评论/问题)：

• 语句x = condition ? value1 : value2中的?:运算符称为conditional operator。如果condition为true，并且value2 value1为nullable integer，则返回null，该值可以是整数值，也可以是null。

Answer 2

当然，你可以做的一件事就是改进你写条件句的方式。我认为将条件提取到方法中来描述检查的实际操作可能会更好，而不是到处添加注释。

Answer 3

为什么你不关注分配目标，而不是条件呢？

条件看起来很简单，而且是重复的。一个例子：

ViewBag.hideHelmet = formvalues["helmets"] == ""? 1 : 0;

这不需要任何分支逻辑。