Ruby - Filter nested JSON based on uniqueness and push to array-CodePudding

I have a json with a main key called section and nested objects of each product within products array.

My json:

{
  "data": [
      {
          "section": 0,
          "products": [
              {
                  "product": "Name 1",
                  "rate": 79.96
              },
              {
                  "product": "Name 2",
                  "rate": 45.96
              }
          ]
      },
      {
          "section": 1,
          "products": [
              {
                  "product": "Name 1",
                  "rate": 86.06
              },
              {
                  "product": "Name 2",
                  "rate": 98.96
              }
          ]
      },
      {
          "section": 2,
          "products": [
              {
                  "product": "Name 1",
                  "rate": 78.95
              },
              {
                  "product": "Name 2",
                  "rate": 24.96
              }
          ]
      },
      {
          "section": 3,
          "products": [
              {
                  "product": "Name 1",
                  "rate": 76.11
              },
              {
                  "product": "Name 2",
                  "rate": 74.96
              }
          ]
      },
      {
          "section": 4,
          "products": [
              {
                  "product": "Name 1",
                  "rate": 76.07
              },
              {
                  "product": "Name 2",
                  "rate": 58.96
              }
          ]
      },
      {
          "section": 5,
          "products": [
              {
                  "product": "Name 1",
                  "rate": 81.15
              },
              {
                  "product": "Name 2",
                  "rate": 15.96
              }
          ]
      }
  ]
}

How am I able to search within the products in all the sections and find the lowest rate for a product with the uniqueness of each product name within the whole data and push to its own object or array?

result example:

{
  "data": [
    {
      "product": "Name 1",
      "rate": 76.07,
      "section": 4
    },
    {
        "product": "Name 2",
        "rate": 15.96,
        "section": 5
    }
  ]
}

I would of course show what I've done so far, but I'm not sure even where and how to start.

Thank you in advance!

CodePudding user response：

The best thing to do is break this down into smaller problems. You can reaily use #each_with_object to build a flat array of "products" and add a :section key to each product info hash.

json[:data].each_with_object([]) { |h, arr|
  h[:products].each { |prod|
    arr << { :section => h[:section], **prod }
  }
}

These can be grouped by product name.

json[:data].each_with_object([]) { |h, arr|
  h[:products].each { |prod|
    arr << { :section => h[:section], **prod }
  }
}.group_by { |h| 
  h[:product] 
}

Now we have a hash containing arrays. We really only need the values.

json[:data].each_with_object([]) { |h, arr|
  h[:products].each { |prod|
    arr << { :section => h[:section], **prod }
  }
}.group_by { |h| 
  h[:product] 
}.values

And for each of these, we need the minimum element by the :rate value.

json[:data].each_with_object([]) { |h, arr|
  h[:products].each { |prod|
    arr << { :section => h[:section], **prod }
  }
}.group_by { |h| 
  h[:product] 
}.values.map { |arr|
  arr.min_by { |prod| prod[:rate] }
}

The result:

[{:section=>4, :product=>"Name 1", :rate=>76.07}, 
 {:section=>5, :product=>"Name 2", :rate=>15.96}]