Ruby on Rails doubts

I have this def in models, checked with pry and have values arriving normally, however they do not save in the @inventory variable and below I put the class Inventory too, I wanted to know if anyone could give a help, since jah thank you. p>

MODEL TRADE

        def survivor_owns_items(survivor, trade_items)
        trade_items.each do |trade_item|
            binding.pry 
            @inventory = Inventory.includes(:Survivor,:Item).where({Survivor: survivor, Item: trade_items})
            if @inventory.quantity < trade_items.quantity
                return false
            end
        end

CLASS INVENTORY

           class Inventory < ApplicationRecord
             belongs_to :survivor
             belongs_to :item
            validates :survivor, :item, presence: true
            validates :survivor, uniqueness: { scope: :item }
          end

JSON:

     {
     "trade": {
        "survivor_one_id": "1",        
         "survivor_two_id": "2",
         "survivor_two_items": [{"name": "Water", "quantity":"1"}],                       
         "survivor_one_items": [{"name":"Medication","quantity":"2"}]
        }
     }