remove duplicates from an array when using laravel eloquent relationship in vuejs

Question

So I have an array that has an object inside of it due to eloquent relationship in laravel. So the array looks something like this:

Documents:

[
    {
        "id": 6,
        "name": "document",
        "supplier": {
            "id": 5,
            "name": "H.B.C",
        }
    },
    {
        "id": 5,
        "name": "document",
        "supplier": {
            "id": 5,
            "name": "H.B.C",
        }
    },
    {
        "id": 4,
        "name": "document",
        "supplier": {
            "id": 4,
            "name": "Avrora",
        }
    }
]

Now I'm trying to use lodash to get unique suppliers so in the above example I would want to get back HBC and Avrora without another HBC

What I'm trying:

CollectionSuppliers () {
    return uniq(this.Documents.supplier.map(({ name }) => name))
},

but im getting an error:

Cannot read properties of undefined (reading 'map')

Answer 1

Cannot read properties of undefined (reading 'map')

This means whatever you're calling map on is undefined. You're calling it on:

this.Documents.supplier

so that means supplier is not a property of this.Documents . Which is true! Because this.Documents is an array of objects with a supplier , but the array itself doesn't have a supplier .

What you probably meant to do was:

return uniq(this.Documents.map(doc => doc.supplier.name))

This maps each document to just the supplier name, and then calls uniq on the array of supplier names.

Answer 2

You are accessing the supplier on the this.Documents object, but it doesn't exist, so it produces error

this.Documents.supplier.map(({ name }) => name)

You have to map over the this.Documents not on the this.Documents.supplier as:

CollectionSuppliers() {
  return uniq(this.Documents.map((o) => o.supplier.name));
}

or

CollectionSuppliers() {
  return uniq(this.Documents.map(({ supplier: { name } }) => name));
}

NOTE: You don't need lodash for this, you can get unique elements using vanilla JS also:

 const Documents = [ { id: 6, name: "document", supplier: { id: 5, name: "HBC", }, }, { id: 5, name: "document", supplier: { id: 5, name: "HBC", }, }, { id: 4, name: "document", supplier: { id: 4, name: "Avrora", }, }, ]; const result = [...new Set(Documents.map((o) => o.supplier.name))]; console.log(result);