如何在Ruby中解析和查找JSON元素？

Question

I'm trying to return the lowest result number that it's name is my.name :

{
    "total_results"=>"73", 
    "results"=>
        {
        "28"=> {"description"=>"description_here", "name"=> "my.name"},
        "25"=> {"description"=>"description_here", "name"=> "other1.name"},
        "24"=> {"description"=>"description_here", "name"=> "my.name"},
        "21"=> {"description"=>"description_here", "name"=> "other2.name"}
        }
}

So in the example above it will return 24 . I'm fairly new to Ruby so I'm struggling to find a good way to do this.

Answer 1

Your example is a hash in Ruby

h = {
"total_results"=>"73", 
"results"=>
    {
    "28"=> {"description"=>"description_here", "name"=> "my.name"},
    "25"=> {"description"=>"description_here", "name"=> "other1.name"},
    "24"=> {"description"=>"description_here", "name"=> "my.name"},
    "21"=> {"description"=>"description_here", "name"=> "other2.name"}
    }
}

You can use select to get all matching values, then get min key of them like

h["results"].select{|k,v| v["name"] == "my.name"}.keys.map(&:to_i).min
# => 24

Answer 2

This is a solution. Definitely not the best, but I can at least show you how you can traverse through that hash..

foo = {
"total_results"=>"73", 
"results"=>
    {
    "28"=> {"description"=>"description_here", "name"=> "my.name"},
    "25"=> {"description"=>"description_here", "name"=> "other1.name"},
    "24"=> {"description"=>"description_here", "name"=> "my.name"},
    "21"=> {"description"=>"description_here", "name"=> "other2.name"}
    }
}

bar = nil

foo['results'].each do |k, v|
  if v['name'] == "my.name"
    if bar.nil? || k < bar
      bar = k
    end
  end
end


puts bar  #=> "24"

Answer 3

Try this:

h = {
    "total_results"=>"73", 
    "results"=>
        {
        "28"=> {"description"=>"description_here", "name"=> "my.name"},
        "25"=> {"description"=>"description_here", "name"=> "other1.name"},
        "24"=> {"description"=>"description_here", "name"=> "my.name"},
        "21"=> {"description"=>"description_here", "name"=> "other2.name"}
        }
}

To get the minimum key:

min_key = h["results"].keys.min

To get the min_key value

h["results"][min_key]

Answer 4

A One-Line Solution

Given your posted hash stored in h , you can do the following:

h['results'].select { |k,v| v['name'] == 'my.name' }.keys.min_by(&:to_i)
#=> "24"

Explanation

While this one-liner trades compactness for clarity, it's doing the following:

1. Sifting results with Enumerable#select for values with a nested hash key of 'name'.

2. Returning an interim hash containing hashes where the value assigned to the 'name' key contains your desired string value. For example:

    {"28"=>{"description"=>"description_here", "name"=>"my.name"}, "24"=>{"description"=>"description_here", "name"=>"my.name"}} 

3. Using Enumerable#min_by to coerce the keys to integers for the comparison, then find the smallest value and return it in the original format (eg as a string).

It only looks like magic. It's just Ruby. :)

Answer 5

h = {
    "total_results"=>"73", 
    "results"=>
        {
        "28"=> {"description"=>"description_here", "name"=> "my.name"},
        "25"=> {"description"=>"description_here", "name"=> "other1.name"},
        "24"=> {"description"=>"description_here", "name"=> "my.name"},
        "21"=> {"description"=>"description_here", "name"=> "other2.name"}
        }
} 

h["results"].select{|key,hash| [key, hash] if hash["name"]=="my.name"}.keys.map(&:to_i).min

=> 24

Answer 6

只需一行代码即可找到min_key ：

min_key = your_hash['results'].sort.to_h.invert['my.name']