how to pass variable from a class to another class in ruby - ruby

Question

I'm trying to extract data from mongodb to Elasticsearch, getMongodoc = coll.find().limit(10)
will find the first 10 entries in mongo.
As you can see , result = ec.mongoConn should get result from method mongoConn() in class MongoConnector. when I use p hsh(to examine the output is correct), it will print 10 entires, while p result = ec.mongoConn will print #<Enumerator: #<Mongo::Cursor:0x70284070232580 #view=#<Mongo::Collection::View:0x70284066032180 namespace='mydatabase.mycollection' #filter={} #options={"limit"=>10}>>:each>
I changed p hsh to return hsh, p result = ec.mongoConn will get the correct result, but it just prints the first entry not all 10 entries. it seems that the value of hsh did not pass to result = ec.mongoConn correctly, Can anyone tell me what am I doing wrong? is this because I did something wrong with method calling?
class MongoConncetor
def mongoConn()
BSON::OrderedHash.new
client = Mongo::Client.new([ 'xx.xx.xx.xx:27017' ], :database => 'mydatabase')
coll = client[:mycollection]
getMongodoc = coll.find().limit(10)
getMongodoc.each do |document|
hsh = symbolize_keys(document.to_hash).select { |hsh| hsh != :_id }
return hsh
# p hsh
end
end
class ElasticConnector < MongoConncetor
include Elasticsearch::API
CONNECTION = ::Faraday::Connection.new url: 'http://localhost:9200'
def perform_request(method, path, params, body)
puts "--> #{method.upcase} #{path} #{params} #{body}"
CONNECTION.run_request \
method.downcase.to_sym,
path,
((
body ? MultiJson.dump(body) : nil)),
{'Content-Type' => 'application/json'}
end
ec = ElasticConnector.new
p result = ec.mongoConn
client = ElasticConnector.new
client.bulk index: 'myindex',
type:'test' ,
body: result
end

Answer 1

You are calling return inside a loop (each). This will stop the loop and return the first result. Try something like:
getMongodoc.map do |document|
symbolize_keys(document.to_hash).select { |hsh| hsh != :_id }
end
Notes:
In ruby you usually don't need the return keyword as the last value is returned automatically. Usually you'd use return to prevent some code from being executed
in ruby snake_case is used for variable and method names (as opposed to CamelCase or camelCase)
map enumerates a collection (by calling the block for every item in the collection) and returns a new collection of the same size with the return values from the block.
you don't need empty parens () on method definitions
UPDATE:
The data structure returned by MongoDB is a Hash (BSON is a special kind of serialization). A Hash is a collection of keys ("_id", "response") that point to values. The difference you point out in your comment is the class of the hash key: string vs. symbol
In your case a document in Mongo is represented as Hash, one hash per document
If you want to return multiple documents, then an array is required. More specifically an array of hashes: [{}, {}, ...]
If your target (ES) does only accept one hash at a time, then you will need to loop over the results from mongo and add them one by one:
list_of_results = get_mongo_data
list_of_results.each do |result|
add_result_to_es(result)
end