Organize a flat array of objects into a better structure (~50% smaller)

1-input-data.json

[
  {
    "brand": {
      "name": "Antonio's Pizzeria",
      "slug": "1532df73-c60f-4cca-b03d-f535e031a7e1"
    },
    "location": {
      "id": 1,
      "name": "Downtown"
    },
    "menu": {
      "slug": "7851b71a-4c88-4fb8-9546-8ec9537397ab",
      "name": "Lunch Menu"
    }
  },
  {
    "brand": {
      "name": "Antonio's Pizzeria",
      "slug": "1532df73-c60f-4cca-b03d-f535e031a7e1"
    },
    "location": {
      "id": 1,
      "name": "Downtown"
    },
    "menu": {
      "slug": "a4bede2e-be21-4e30-8263-874e1e77dde9",
      "name": "Breakfast Menu"
    }
  },
  {
    "brand": {
      "name": "Antonio's Pizzeria",
      "slug": "1532df73-c60f-4cca-b03d-f535e031a7e1"
    },
    "location": {
      "id": 2,
      "name": "Valley"
    },
    "menu": {
      "slug": "d93473ad-e8ab-4461-892e-6593d29e598f",
      "name": "Breakfast Menu"
    }
  },
  {
    "brand": {
      "name": "Antonio's Pizzeria",
      "slug": "1532df73-c60f-4cca-b03d-f535e031a7e1"
    },
    "location": {
      "id": 2,
      "name": "Valley"
    },
    "menu": {
      "slug": "78960d5d-823a-4501-bdd2-86522f1681f3",
      "name": "Dinner Menu"
    }
  },
  {
    "brand": {
      "name": "Antonio's Pizzeria",
      "slug": "1532df73-c60f-4cca-b03d-f535e031a7e1"
    },
    "location": {
      "id": 2,
      "name": "Valley"
    },
    "menu": {
      "slug": "a7fb8a9d-8036-497e-9a7a-1e1e3daeaf88",
      "name": "Lunch Menu"
    }
  }
]

2-transform.js

const _ = require('lodash')

function uniqueLocations (data) {
  // First get a list of unique brands
  const out = _.uniqBy(data.map(r => r.brand), r => r.slug)

  // Then add on the locations and menus
  out.forEach(brand => {
    // Find unique matching locations for each brand
    const mloc = _.uniqBy(data
      .filter(r => r.brand.slug === brand.slug)
      .map(r => r.location), r => r.id)
    // Attach menus for each location
    mloc.forEach(loc => {
      const menus = _.uniqBy(data.filter(r =>
        r.brand.slug === brand.slug &&
        r.location.id === loc.id
      ).map(r => r.menu), r => r.slug)
      loc.menus = menus
    })
    brand.locations = mloc
  })

  return out
}

3-output.json

[
  {
    "name": "Antonio's Pizzeria",
    "slug": "1532df73-c60f-4cca-b03d-f535e031a7e1",
    "locations": [
      {
        "id": 1,
        "name": "Downtown",
        "menus": [
          {
            "slug": "7851b71a-4c88-4fb8-9546-8ec9537397ab",
            "name": "Lunch Menu"
          },
          {
            "slug": "a4bede2e-be21-4e30-8263-874e1e77dde9",
            "name": "Breakfast Menu"
          }
        ]
      },
      {
        "id": 2,
        "name": "Valley",
        "menus": [
          {
            "slug": "d93473ad-e8ab-4461-892e-6593d29e598f",
            "name": "Breakfast Menu"
          },
          {
            "slug": "78960d5d-823a-4501-bdd2-86522f1681f3",
            "name": "Dinner Menu"
          },
          {
            "slug": "a7fb8a9d-8036-497e-9a7a-1e1e3daeaf88",
            "name": "Lunch Menu"
          }
        ]
      }
    ]
  }
]