cannot have more than 1 script sorting

[jiajiawang]

In elasticsearch, you can have as many script sorting as you want.
For example, there is a test index with two keyword fields "region" and "country", to sort by region and country alphabetically, by using script sorting you can do

{
  "sort": [
    {
      "_script": {
        "type": "string",
        "script": {
          "inline": "doc['region'].value"
        },
        "order": "desc"
      }
    },
    {
      "_script": {
        "type": "string",
        "script": {
          "inline": "doc['country'].value"
        },
        "order": "desc"
      }
    }
  ]
}

(In real world, you can simply do { "sort": ["region", "country"] }, this example is just to explain the issue)
However, when I use the order method of chewy I can't add more than 1 script sorting

TestsIndex.order([
    {
      "_script": {
        "type": "string",
        "script": {
          "inline": "doc['region'].value"
        },
        "order": "desc"
      }
    },
    {
      "_script": {
        "type": "string",
        "script": {
          "inline": "doc['country'].value"
        },
        "order": "desc"
      }
    }
  ])

it returns

<TestsIndex::Query {:index=>["tests"], :type=>["user"], :body=>{:sort=>[{"_script"=>{:type=>"string", :script=>{:inline=>"doc['country'].value"}, :order=>"desc"}}]}}>

The region script sorting part is gone.

---

Expected behavior

Expect query to be like

<TestsIndex::Query {:index=>["tests"], :type=>["user"], :body=>{:sort=>[{"_script"=>{:type=>"string", :script=>{:inline=>"doc['region'].value"}, :order=>"desc"}}, {"_script"=>{:type=>"string", :script=>{:inline=>"doc['country'].value"}, :order=>"desc"}}]}}>

Actual behavior

Actual query is

<TestsIndex::Query {:index=>["tests"], :type=>["user"], :body=>{:sort=>[{"_script"=>{:type=>"string", :script=>{:inline=>"doc['country'].value"}, :order=>"desc"}}]}}>

Steps to reproduce the problem

Define index

class TestsIndex < Chewy::Index
  define_type User do
    field :region, type: :keyword
    field :country, type: :keyword
  end
end

Then in console do

TestsIndex.order([
    {
      "_script": {
        "type": "string",
        "script": {
          "inline": "doc['region'].value"
        },
        "order": "desc"
      }
    },
    {
      "_script": {
        "type": "string",
        "script": {
          "inline": "doc['country'].value"
        },
        "order": "desc"
      }
    }
  ])

Version Information

Chewy 5.0.0 and 6.0.0 and 7.0.0
Elasticsearch 6.4
ruby 2.6.6p146 (2020-03-31 revision 67876) [x86_64-darwin19]
Rails 5.1.7

---

By looking into the source code, I found that the value of Chewy::Search::Parameters::Order is a hash and the issue is because the key of script sorting must always be "_script".

=> #<Chewy::Search::Parameters:0x00007fa76fb3c950
 @storages=
  {:order=>#<Chewy::Search::Parameters::Order:0x00007fa76fb3c6a8 @value={"_script"=>{:type=>"string", :script=>{:inline=>"doc['country'].value"}, :order=>"desc"}}>,
   :types=>#<Chewy::Search::Parameters::Types:0x00007fa76fb4f438 @value=[]>,
   :none=>#<Chewy::Search::Parameters::None:0x00007fa76fb4ea60 @value=false>,
   :filter=>#<Chewy::Search::Parameters::Filter:0x00007fa76fb4ea38 @value=#<Chewy::Search::Parameters::QueryStorage::Bool:0x00007fa76fb4e7e0 @minimum_should_match=nil, @must=[], @must_not=[], @should=[]>>,
   :query=>#<Chewy::Search::Parameters::Query:0x00007fa76fb4e3d0 @value=#<Chewy::Search::Parameters::QueryStorage::Bool:0x00007fa76fb4e1c8 @minimum_should_match=nil, @must=[], @must_not=[], @should=[]>>}>

[rabotyaga]

Hey @jiajiawang 👋 !
Thanks for the report. Are you interested in submitting a PR with a fix?

[jiajiawang]

Hey @jiajiawang 👋 !
Thanks for the report. Are you interested in submitting a PR with a fix?

Hey @rabotyaga, Yes, I'm interested in it.
Not sure how hard it would be, but I'm happy to give a try.
In term of the fix, I assume we'll have to change to use array as the storage of Order param.
Would love to hear your thoughts and ideas on it first.

[rabotyaga]

Hey @jiajiawang 👋 !

Hey @rabotyaga, Yes, I'm interested in it.

Great! And thanks!

Not sure how hard it would be, but I'm happy to give a try.
In term of the fix, I assume we'll have to change to use array as the storage of Order param.
Would love to hear your thoughts and ideas on it first.

Yep, I believe we should change the Chewy::Search::Parameters::Order implementation to use Array under the hood.