How to store the same key multi times in a Hash ?

rubyonrails-talk
1

given an Arra tags

I need to produce a resulting Hash as following ..

{ "$in" => [tags[0]], "$in" =>[tags[1], ...}

in which the key should be always the same and the value being an Array

I tried this :

         myHash = {}          tags.each do |tag|            h = {"$in" => [tag]}            myHash.merge!(h)          end

but the merge! is only changing the value ... (as the key is always the same ..) (there is no += as with Array class ...)

thanks for your feedback

2

By definition, a hash stores a single value for a given key. The closest you'll get is to make the value an array of all the things for the key in question.

Fred

3

I agree with Frederick Cheung.

Your code will be like this :

  myHashes =   tags.each do |tag|     h = {"$in" => [tag]}     myHash << h   end

and myHashes will contains :

  [{ "$in" => [tags[0]]}, {"$in" =>[tags[1]}, ...]

which myHashes is an array of hashes.

Hope this can help you :slight_smile:

4

thanks a lot .. !!!

5

this is to be used with MongoID as a criteria

criteria.where(:tags => { "$in" => [tags[0]], "$in" =>[tags[1]] }).to_a

any suggestion with json structure ?

thanks Fred

6

this is to be used with MongoID as a criteria

criteria.where(:tags => { "$in" => [tags[0]], "$in" =>[tags[1]] }).to_a

any suggestion with json structure ?

You can't repeat keys in a json hash either. What are you actually trying to do?

Fred

7

I need to write a Mongoid criteria

criteria.where(:tags => myStruct ).to_a

in which myStruct will have this structure { "$in" => [check_tags[0]], "$in" =>[check_tags[1]] , .. } built from a check_tags Array

it's a sequence of .in criteria I am checking if ALL of the elements of check_tags are included in a Mongoid record Array field :tags

the simplest Mongoid criteria: criteria.in(:tags => tags) just perform a checking on ANY element included, not ALL

8

Thanks fred .. found how to do it.... there is a specific criteria for it ( I did not fully understand when reading it the first time...)

Criteria#all_in: Matches if all values provided match, useful for doing exact matches on arrays.

so writing : criteria.all_in(:tags => tags ).to_a

did it ...

I'll try to give an eye to the underlaying Mongoid ruby code in charge of doing that ....