CODEWITHSUNDEEP
rubyjsonsinatra
Todd Guerra
Todd Guerra

Reputation: 3

How to parse a more complicated JSON object in Ruby on Sinatra

I'm a Java guy, new to Ruby. I've been playing with it just to see what it can do, and I'm running into an issue that I can't solve.

I decided to try out Sinatra, again, just to see what it can do, and decided to play with the ESPN API and see if I can pull the venue of a team via the API.

I'm able to make the call and get the data back, but I am having trouble parsing it:

{"sports"=>[{"name"=>"baseball", "id"=>1, "uid"=>"s:1", "leagues"=>[{"name"=>"Major League Baseball", "abbreviation"=>"mlb", "id"=>10, "uid"=>"s:1~l:10", "groupId"=>9, "shortName"=>"MLB", "teams"=>[{"id"=>17, "uid"=>"s:1~l:10~t:17", "location"=>"Cincinnati", "name"=>"Reds", "abbreviation"=>"CIN", "color"=>"D60042", "venues"=>[{"id"=>83, "name"=>"Great American Ball Park", "city"=>"Cincinnati", "state"=>"Ohio", "country"=>"", "capacity"=>0}], "links"=>{"api"=>{"teams"=>{"href"=>"http://api.espn.com/v1/sports/baseball/mlb/teams/17"}, "news"=>{"href"=>"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news"}, "notes"=>{"href"=>"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news/notes"}}, "web"=>{"teams"=>{"href"=>"http://espn.go.com/mlb/team/_/name/cin/cincinnati-reds?ex_cid=espnapi_public"}}, "mobile"=>{"teams"=>{"href"=>"http://m.espn.go.com/mlb/clubhouse?teamId=17&ex_cid=espnapi_public"}}}}]}]}], "resultsOffset"=>0, "resultsLimit"=>50, "resultsCount"=>1, "timestamp"=>"2013-08-04T14:47:13Z", "status"=>"success"}

I want to pull the venues part of the object, specifically the name value. Every time I try to parse it I end up getting an error along the lines of "cannot change from nil to string" and then also I've gotten an integer to string error.

Here's what i have so far: 

get '/venue/:team' do

    id = ids[params[:team]]
    url = 'http://api.espn.com/v1/sports/baseball/mlb/teams/' + id + '?enable=venues&apikey=' + $key
    resp = Net::HTTP.get_response(URI.parse(url))
    data = resp.body
    parsed = JSON.parse(resp.body)
    #venueData = parsed["sports"]

    "Looking for the venue of the #{params[:team]}, which has id " + id + ", and here's the data returned: " + venueData.to_s

end

When I do parsed["sports"} I get:

 [{"name"=>"baseball", "id"=>1, "uid"=>"s:1", "leagues"=>[{"name"=>"Major League Baseball", "abbreviation"=>"mlb", "id"=>10, "uid"=>"s:1~l:10", "groupId"=>9, "shortName"=>"MLB", "teams"=>[{"id"=>17, "uid"=>"s:1~l:10~t:17", "location"=>"Cincinnati", "name"=>"Reds", "abbreviation"=>"CIN", "color"=>"D60042", "venues"=>[{"id"=>83, "name"=>"Great American Ball Park", "city"=>"Cincinnati", "state"=>"Ohio", "country"=>"", "capacity"=>0}], "links"=>{"api"=>{"teams"=>{"href"=>"http://api.espn.com/v1/sports/baseball/mlb/teams/17"}, "news"=>{"href"=>"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news"}, "notes"=>{"href"=>"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news/notes"}}, "web"=>{"teams"=>{"href"=>"http://espn.go.com/mlb/team/_/name/cin/cincinnati-reds?ex_cid=espnapi_public"}}, "mobile"=>{"teams"=>{"href"=>"http://m.espn.go.com/mlb/clubhouse?teamId=17&ex_cid=espnapi_public"}}}}]}]}]

But nothing else parses. Please help!

Like I said, I'm not trying to do anything fancy, just figure out Ruby a little for fun, but I have been stuck on this issue for days now. Any help would be appreciated!

EDIT:

JSON straight from the API:

{"sports" :[{"name" :"baseball","id" :1,"uid" :"s:1","leagues" :[{"name" :"Major League Baseball","abbreviation" :"mlb","id" :10,"uid" :"s:1~l:10","groupId" :9,"shortName" :"MLB","teams" :[{"id" :17,"uid" :"s:1~l:10~t:17","location" :"Cincinnati","name" :"Reds","abbreviation" :"CIN","color" :"D60042","venues" :[{"id" :83,"name" :"Great American Ball Park","city" :"Cincinnati","state" :"Ohio","country" :"","capacity" :0}],"links" :{"api" :{"teams" :{"href" :"http://api.espn.com/v1/sports/baseball/mlb/teams/17"},"news" :{"href" :"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news"},"notes" :{"href" :"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news/notes"}},"web" :{"teams" :{"href" :"http://espn.go.com/mlb/team/_/name/cin/cincinnati-reds?ex_cid=espnapi_public"}},"mobile" :{"teams" :{"href" :"http://m.espn.go.com/mlb/clubhouse?teamId=17&ex_cid=espnapi_public"}}}}]}]}],"resultsOffset" :0,"resultsLimit" :50,"resultsCount" :1,"timestamp" :"2013-08-05T19:44:32Z","status" :"success"}

The result of data.inspect:

"{\"sports\" :[{\"name\" :\"baseball\",\"id\" :1,\"uid\" :\"s:1\",\"leagues\" :[{\"name\" :\"Major League Baseball\",\"abbreviation\" :\"mlb\",\"id\" :10,\"uid\" :\"s:1~l:10\",\"groupId\" :9,\"shortName\" :\"MLB\",\"teams\" :[{\"id\" :17,\"uid\" :\"s:1~l:10~t:17\",\"location\" :\"Cincinnati\",\"name\" :\"Reds\",\"abbreviation\" :\"CIN\",\"color\" :\"D60042\",\"venues\" :[{\"id\" :83,\"name\" :\"Great American Ball Park\",\"city\" :\"Cincinnati\",\"state\" :\"Ohio\",\"country\" :\"\",\"capacity\" :0}],\"links\" :{\"api\" :{\"teams\" :{\"href\" :\"http://api.espn.com/v1/sports/baseball/mlb/teams/17\"},\"news\" :{\"href\" :\"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news\"},\"notes\" :{\"href\" :\"http://api.espn.com/v1/sports/baseball/mlb/teams/17/news/notes\"}},\"web\" :{\"teams\" :{\"href\" :\"http://espn.go.com/mlb/team/_/name/cin/cincinnati-reds?ex_cid=espnapi_public\"}},\"mobile\" :{\"teams\" :{\"href\" :\"http://m.espn.go.com/mlb/clubhouse?teamId=17&ex_cid=espnapi_public\"}}}}]}]}],\"resultsOffset\" :0,\"resultsLimit\" :50,\"resultsCount\" :1,\"timestamp\" :\"2013-08-05T19:44:24Z\",\"status\" :\"success\"}"

Upvotes: 0

Views: 368

Answers (2)

ian
ian

Reputation: 12251

With the data you've provided in the question, you can get to the venues information like this:

require 'json'

json = JSON.parse data

json["sports"].first["leagues"].first["teams"].first["venues"]
# => [{"id"=>83, "name"=>"Great American Ball Park", "city"=>"Cincinnati", "state"=>"Ohio", "country"=>"", "capacity"=>0}]

By replacing each of the first calls with an iterator, you can search through without knowing where the data is:

json["sports"].each{|h|
  h["leagues"].each{|h|
    h["teams"].each{|h|
      venues = h["venues"].map{|h| h["name"]}.join(", ")
      puts %Q!name: #{h["location"]} #{h["name"]} venues: #{venues}!
    }
  }
}

This outputs:

name: Cincinnati Reds venues: Great American Ball Park

Depending on how stable the response data is you may be able to cut out several of the iterators:

json["sports"].first["leagues"]
              .first["teams"]
              .each{|h|
                venues = h["venues"].map{|h| h["name"] }.join(", ")
                puts %Q!name: #{h["location"]} #{h["name"]} venues: #{venues}!
              }

and you'll most likely want to save the data, so something like each_with_object is helpful:

team_and_venues = json["sports"].first["leagues"]
              .first["teams"]
              .each_with_object([]){|h,xs|
                venues = h["venues"].map{|h| h["name"]}.join(", ")
                xs << %Q!name: #{h["location"]} #{h["name"]} venues: #{venues}!
              }
# => ["name: Cincinnati Reds venues: Great American Ball Park"]

team_and_venues
# => ["name: Cincinnati Reds venues: Great American Ball Park"]

Notice that when an iterator declares variables, even if there is a variable with the same name outside the block, the scope of the block is respected and the block's variables remain local.

That's some pretty ugly code if you ask me, but it's a place to start.

Upvotes: 0

kwarunek
kwarunek

Reputation: 12577

parsed["sports"] does not exist, parse your input and inspect it/ dump it

Upvotes: 1

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