How to flatten nested arrays based on a key of its members

Question

I have the following JSON object:

{
  "name": "Womens",
  "position": 1,
  "url": "/collections/womens-all",
  "submenus": [
    {
      "name": "Apparel",
      "position": 1,
      "url": "/collections/womens-apparel-all",
      "submenus": [
        {
          "name": "Tees & Tanks",
          "position": 1,
          "url": "/collections/womens-tees",
          "submenus": []
        },
        {
          "name": "Silk & Tops",
          "position": 2,
          "url": "/collections/womens-tops",
          "submenus": []
        },
        {
          "name": "Sweaters & Sweatshirts",
          "position": 3,
          "url": "/collections/womens-sweaters",
          "submenus": []
        }
      ]
    },
    {
      "name": "Accessories",
      "position": 2,
      "url": "/collections/womens-all-accessories",
      "submenus": [
        {
          "name": "Petra",
          "position": 1,
          "url": "/collections/petra",
          "submenus": []
        },
        {
          "name": "Weekenders",
          "position": 2,
          "url": "/collections/womens-bags",
          "submenus": []
        },
        {
          "name": "Backpacks & Totes",
          "position": 3,
          "url": "/collections/womens-backpacks",
          "submenus": []
        },
        {
          "name": "Accessories & Shoes",
          "position": 4,
          "url": "/collections/womens-accessories",
          "submenus": []
        }
      ]
    }
  ]
}

I want to flatten this object's submenus into a single array containing every menu in the tree. The result would look like:

[
  {
    "name": "Apparel",
    "position": 1,
    "url": "/collections/womens-apparel-all",
    "submenus": []
  },
  {
    "name": "Accessories",
    "position": 2,
    "url": "/collections/womens-all-accessories",
    "submenus": []
  },
  {
    "name": "Petra",
    "position": 1,
    "url": "/collections/petra",
    "submenus": []
  },
  {
    "name": "Weekenders",
    "position": 2,
    "url": "/collections/womens-bags",
    "submenus": []
  },
  {
    "name": "Backpacks & Totes",
    "position": 3,
    "url": "/collections/womens-backpacks",
    "submenus": []
  },
  {
    "name": "Accessories & Shoes",
    "position": 4,
    "url": "/collections/womens-accessories",
    "submenus": []
  },
  {
    "name": "Tees & Tanks",
    "position": 1,
    "url": "/collections/womens-tees",
    "submenus": []
  },
  {
    "name": "Silk & Tops",
    "position": 2,
    "url": "/collections/womens-tops",
    "submenus": []
  },
  {
    "name": "Sweaters & Sweatshirts",
    "position": 3,
    "url": "/collections/womens-sweaters",
    "submenus": []
  }
]

I feel like a recursive solution would be best, but I can't get it right. What would be the best approach for this problem?

Answer 1

This should do, assuming you forgot "Womens" in the resulting array in your example:

def flatten(dct, res=None):
    if res is None:
        res = []
    subdct = {}
    for k in dct:
        v = dct[k]
        if k == "submenus":
            for e in v:
                flatten(e, res)
            v = []
        subdct[k] = v
    res.append(subdct)
    return res

to be called like

result = flatten(json_object)