Handling Document Updates without Unique Identifier in Laravel Pivot Table

I'm working on a Laravel project where I'm fetching product data from an API that includes associated documents. The documents are stored in a separate table with a pivot table (product_document) due to a many-to-many relationship between products and documents. The challenge I'm facing is that the API response lacks a unique identifier for the documents, and I need to determine whether a document should be updated or created for a given product.

API response example:

$productdata = [ 'id' => 757, 'code' => 'tee', 'name' => 'Long tee shirt', 'supplier_productcode' => 'Penshoppe', 'weight' => 5, 'unit' => 0, 'stocklevel' =>100, 'min_stocklevel' => 0, 'documents' => [ [ 'name' => 'productDocs.PDF', 'size' => 70984, ], [ 'name' => 'shirtDesign.PDF', 'size' => 110868, ], ], 'updated_at' => '2023-05-23 13:39:18', ];

The relevant portions of my code are as follows:

// Pivot Table (product_document) id = Primary key product_id = Foreign key for Product Table document_id = Foreign key for Document table

// Product Table id = Primary key api_id = ID from the API response

// Document Table id = Primary key name= Name of the document size = Size of the document

// Product Model public function documents(): BelongsToMany { return $this->belongsToMany(Document::class, 'product_document')->using(ProductDocument::class); }

//Fetching and Updating

foreach ($products as $product) {

                $product_lastUpdate = $product['updated_at'];
                if (Carbon::parse($product_lastUpdate) == '2023-05-23 13:39:18') {

			// Code for updating or creating products
                    $upProduct = Product::updateOrCreate(
                        [
                            'api_id' => $product['id']
                        ],                    
                        [
                            'api_id' => $product['api_id'],
                            'code' => $product['code'],
                            'name' => $product['name'],
                            'supplier_productcode' => $product['supplier_productcode'],
                            'weight' => $product['weight'],
                            'unit' => $product['unit'],
                            'stocklevel' => $product['stocklevel'],
                            'min_stocklevel' => $product['min_stocklevel'],
                        ] 
                    );

					// Code for updating or creating documents
                    foreach ($product['documents'] as $key => $document) {
					// How to handle updates or creations here without a unique identifier?
                    }
                }
            }
        }

I've considered checking for changes in name and size attributes, but it seems insufficient. How can I approach this problem to accurately determine whether a document should be updated or a new one created?

I'm open to alternative solutions or suggestions on how to handle this situation more effectively. Any insights or code examples would be greatly appreciated.

Thank you in advance!