How to write customizer function for lodash _.mergeWith third argument in this situation?

Question

I have two objects like that:

var obj3 = {
    customer_id: 1,
    products: { id: 1, name: "Car" },
  };

  var obj4 = {
    customer_id: 1,
    products: { id: 2, name: "Dress" },
  };

and the expected object is:

result = {
    customer_id: 1,
    products: [
      { id: 1, name: "Car" },
      { id: 2, name: "Dress" },
    ],
  };

How can i write function customizer(){} in this situation? Thanks so much for your help, and i'll be welcome for other solution with different way.

Answer 1

Merge the objects to a new object (the {}). Set the default values of the merged values to empty arrays. If the key is products concat them. If not return undefined, so the standard logic of _.merge() would be used:

const obj3 = { customer_id: 1, products: { id: 1, name: "Car" }, };
const obj4 = { customer_id: 1, products: { id: 2, name: "Dress" }, };

const result = _.mergeWith({}, obj3, obj4, (v1 = [], v2 = [], key) =>
  key === 'products' ? v1.concat(v2) : undefined
)

console.log(result)

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