如何在jbuilder視圖中返回空字符串而不是null？

Question

我有簡單的JBuilder視圖

json.id pharmaceutic.id 
json.name pharmaceutic.name 
json.dosage pharmaceutic.dosage.name 

當pharmaceutic.dosage => nil

我的渲​​染JSON看起來象下面這樣：

{"id":1,"name":"HerzASS ratiopharm","dosage":null} 

我想設置爲所有JBuilder的意見，當某些屬性是nil它應該呈現爲空字符串。

{"id":1,"name":"HerzASS ratiopharm","dosage":""} 

如何做到這一點？

Answer 1

nil.to_s #=> ""所以，你可以簡單地添加.to_s

json.id pharmaceutic.id 
json.name pharmaceutic.name.to_s 
json.dosage pharmaceutic.dosage.name.to_s 

Answer 2

要延長接受的答案，這裏有一個簡單的代理類來做到這一點：

class Proxy 

    def initialize(object) 
    @object = object 
    end 

    def method_missing method, *args, &block 
    if @object.respond_to? method 
     @object.send(method, *args, &block).to_s 
    else 
     super method, *args, &block 
    end 
    end 

    def respond_to? method, private = false 
    super(method, private) || @object.respond_to?(method, private) 
    end 

end 

class Roko < Struct.new(:a, :b, :c) 
end 

# instantiate the proxy instance by giving it the reference to the object in which you don't want nils 
roko = Proxy.new(Roko.new) 

puts roko.a.class # returns String even though :a is uninitialized 
puts roko.a  # returns blank 

Answer 3

json.dosage藥用。 dose.name.to_s

這是行不通的製藥是零。你可以簡單地做

json.dosage pharmaceutic.dosage.name unless pharmaceutic.dosage.nil?