Reduce a Javascript Array of Objects using nested keys

Question

I have the following array which contains a list of javascript objects. I am trying to use the reduce function to convert it into a single object with nested key groupings.

The array looks like the following:

 [ { "product": 1, "date": "2020-01-01", "price": 100 }, { "product": 2, "date": "2020-01-01", "price": 102 }, { "product": 1, "date": "2020-01-02", "price": 99 }, { "product": 2, "date": "2020-01-02", "price": 92 }, { "product": 1, "date": "2020-01-03", "price": 101 }, { "product": 2, "date": "2020-01-03", "price": 22 } ]

And this is the result which I am trying to achieve:

 { 1:{ "2020-01-01":{ "product": 1, "date": "2020-01-01", "price": 100 }, "2020-01-02":{ "product": 1, "date": "2020-01-02", "price": 99 }, "2020-01-03":{ "product": 1, "date": "2020-01-03", "price": 101 } }, 2:{ "2020-01-01":{ "product": 2, "date": "2020-01-01", "price": 102 }, "2020-01-02":{ "product": 2, "date": "2020-01-02", "price": 92 }, "2020-01-03":{ "product": 2, "date": "2020-01-03", "price": 22 } } }

I have tried the following but I only get a single date per product:

 pricelist.reduce((obj, item) => { obj[item['product']] = {}; obj[item['date']][item['product']] = item; return obj; }, {});

Please may you help me understand what I'm doing wrong?

Answer 1

By having only one product per date, you could take the direct target for assigning.

In your approach you changed product with date and this does not work.

 var pricelist = [{ product: 1, date: "2020-01-01", price: 100 }, { product: 2, date: "2020-01-01", price: 102 }, { product: 1, date: "2020-01-02", price: 99 }, { product: 2, date: "2020-01-02", price: 92 }, { product: 1, date: "2020-01-03", price: 101 }, { product: 2, date: "2020-01-03", price: 22 }], result = pricelist.reduce((obj, item) => { obj[item.product] = obj[item.product] || {}; obj[item.product][item.date] = item; return obj; }, {}); console.log(result);

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