Ruby，访问哈希中的嵌套值

Question

I have the following hash. Using ruby, I want to get the value of "runs". I can't figure out how to do it. If I do my_hash['entries'] , I can dig down that far. If I take that value and dig down lower, I get this error: no implicit conversion of String into Integer:

{"id"=>2582, "entries"=>[{"id"=>"7", "runs"=>[{"id"=>2588, ...

Answer 1

Assuming that you want to lookup values by id , Array#detect comes to the rescue:

h = {"id"=>2582, "entries"=>[{"id"=>"7", "runs"=>[{"id"=>2588}]}]}
#           ⇓⇓⇓⇓⇓⇓⇓ lookup element with id = 7 
h['entries'].detect { |e| e['id'] == 7 }['runs']
            .detect { |e| e['id'] == 2588 }
#⇒ { "id" => 2588 }

Answer 2

As you have an array inside the entries so you can access it using an index like this:

my_hash["entries"][0]["runs"]

You need to follow the same for accessing values inside the runs as it is also an array.

Hope this helps.

Answer 3

I'm not sure about your hash, as it's incomplete. So , guessing you have multiple run values like:

hash = {"id"=>2582, "entries"=>[{"id"=>"7", "runs"=>[{"id"=>2588}]},
                                {"id"=>"8", "runs"=>[{"id"=>2589}]},
                                {"id"=>"9", "runs"=>[{"id"=>2590}]}]}

Then, you can do

hash["entries"].map{|entry| entry["runs"]}

OUTPUT

[[{"id"=>2588}], [{"id"=>2589}], [{"id"=>2590}]]