如何检查params [：some] [：field]是否为零？

I tried code, that plused a lot of people - How to test if parameters exist in rails, but it didn't work():

我尝试了很多人的代码 - 如何测试rails中是否存在参数，但它不起作用（）：

     if ( params.has_key?([:start_date]) && params.has_key?([:end_date]) )

I think, that is because of complicated params and if I write this:

我想，那是因为复杂的参数，如果我写这个：

       if ( params.has_key?([:report][:start_date]) && params.has_key?([:report][:end_date]) )

gives me error

给我错误

        can't convert Symbol into Integer

this doesn't work too:

这也行不通：

           if ( params[:report][:start_date] && params[:report][:end_date] )

gives me error:

给我错误：

        undefined method `[]' for nil:NilClass

It always go into else statement.

它总是进入其他声明。

Here are my params:

这是我的参数：

    report: 
    start_date: 01/08/2012
    end_date: 10/08/2012

Can someone help me ?

有人能帮我吗？

5 个解决方案

#1

 if params[:report] && params[:report][:start_date] && params[:report][:end_date]

#2

Cross-post answer from here:

来自这里的交叉答案：

Ruby 2.3.0 makes this very easy to do with #dig.

Ruby 2.3.0使用#dig非常容易。

h = { foo: {bar: {baz: 1}}}

h.dig(:foo, :bar, :baz)           #=> 1
h.dig(:foo, :zot, :baz)           #=> nil

#3

It would seem you need the following

看起来你需要以下内容

    params[:report].present?

要么

    params[:report].nil?

要么

    params[:report].empty?

depending on what you are trying to check for

取决于您要检查的内容

#4

I have been looking for a better solution too. I found this one:

我一直在寻找更好的解决方案。我找到了这个：

Is there a clean way to avoid calling a method on nil in a nested params hash?

是否有一种干净的方法可以避免在嵌套的params哈希中调用nil上的方法？

params[:some].try(:[], :field)

You get the value or nil if it does not exist.

如果不存在，则获得值或nil。

So I figured let's use try a different way:

所以我认为让我们尝试一种不同的方式：

params[:some].try(:has_key?, :field)

It's not bad. You get nil vs. false if it's not set. You also get true if the param is set to nil.

不算太差。如果没有设置，你会得到零而不是假。如果param设置为nil，也会得到true。

#5

This works to:

这适用于：

if params[:report].has_key?(:start_date)

And maybe add this so you also check if it is not empty:

也许添加这个，所以你也检查它是否为空：

&& !params[:report][:start_date].empty?

#1

 if params[:report] && params[:report][:start_date] && params[:report][:end_date]

#2