Rails，如何循环散列数组或仅散列

Question

I am connecting to an API and I get array of hashes or only 1 hash for the data. So when the data comes as array of hashes;

"extras"=>{"extra"=>[{"id"=>"529216700000100800", "name"=>"Transfer Trogir - Dubrovnik (8 persons max)", "price"=>"290.0", "currency"=>"EUR", "timeunit"=>"0", "customquantity"=>"0", "validdatefrom"=>"1970-01-01", "validdateto"=>"2119-07-20", "sailingdatefrom"=>"1970-01-01", "sailingdateto"=>"2119-07-20", "obligatory"=>"0", "perperson"=>"0", "includedinbaseprice"=>"0", "payableoninvoice"=>"1", "availableinbase"=>"-1", "includesdepositwaiver"=>"0", "includedoptions"=>""}, {"id"=>"528978430000100800", "name"=>"Gennaker + extra deposit (HR)", "price"=>"150.0", "currency"=>"EUR", "timeunit"=>"604800000", "customquantity"=>"0", "validdatefrom"=>"1970-01-01", "validdateto"=>"2119-07-19", "sailingdatefrom"=>"1970-01-01", "sailingdateto"=>"2119-07-19", "obligatory"=>"0", "perperson"=>"0", "includedinbaseprice"=>"0", "payableoninvoice"=>"1", "availableinbase"=>"-1", "includesdepositwaiver"=>"0", "includedoptions"=>""}]

I'am looping through the array to get the values as;

b["extras"]["extra"].each do |extra|
  puts extra["id"]
  puts extra["name"]
end

But when this is not array; only 1 hash, then this is not working, adding each loop makes it array but not array of hashes;

"extras"=>{"extra"=>{"id"=>"640079840000100800", "name"=>"Comfort package (GRE)", "price"=>"235.0", "currency"=>"EUR", "timeunit"=>"0", "customquantity"=>"0", "validdatefrom"=>"1970-01-01", "validdateto"=>"2120-03-25", "sailingdatefrom"=>"2015-01-01", "sailingdateto"=>"2120-03-25", "obligatory"=>"1", "perperson"=>"0", "includedinbaseprice"=>"0", "payableoninvoice"=>"1", "availableinbase"=>"-1", "includesdepositwaiver"=>"0", "includedoptions"=>""}}


b["extras"]["extra"].each do |extra|
  puts extra["id"]
  puts extra["name"]
end

This time, that gives error TypeError (no implicit conversion of String into Integer);

When I type puts extra.inspect ; I get ["id", "640079840000100800"] . So to make it work I should pass extra[1] to get the id number.

But I can not predict either array of hashes or only hash. Is there any easy way to solve this issue that works either array of hashes or just a hash?

Answer 1

Naïve solution: one might check the object's type upfront:

case b["extras"]["extra"]
when Array
    # handle array
when Hash
    # handle hash
end

Proper solution: produce an array of hashes no matter what came.

[*[input]].flatten

and deal with it as with an array having at least one hash element (with each .)

Please also refer to valuable comment by @Stefan below if you have no allergy using Rails helpers.

Answer 2

You could try to use Object#kind_of? to determine whether it is an Array or a Hash instance.

if b["extras"]["extra"].kind_of? Array
    # handle array
elsif b["extras"]["extra"].kind_of? Hash
    # handle hash
end