Rails 5 Active Record Record Invalid Error

I have two Rails model namely Invoice and Invoice_details. An Invoice_details belongs to Invoice, and an Invoice has many Invoice_details. I'm not able to save Invoice_details via Invoice model using accepts_nested_attributes_for in Invoice.

I get the following error :

(0.2ms)  BEGIN
(0.2ms)  ROLLBACK
Completed 422 Unprocessable Entity in 25ms (ActiveRecord: 4.0ms)         
ActiveRecord::RecordInvalid (Validation failed: Invoice details invoice must exist):
app/controllers/api/v1/invoices_controller.rb:17:in `create'

Below is the code snippet for invoice.rb :

class Invoice < ApplicationRecord
  has_many :invoice_details
  accepts_nested_attributes_for :invoice_details
end

The code snippet for invoice_details.rb :

class InvoiceDetail < ApplicationRecord
  belongs_to :invoice
end

The Controller code :

class Api::V1::InvoicesController < ApplicationController
  respond_to :json

  def index
    comp_id = params[:comp_id]
    if comp_id
      invoices = Invoice.where(:company_id => comp_id)
      render json: invoices, status: 201
    else
      render json: { errors: "Company ID is NULL" }, status: 422
    end
  end

  def create
    Rails.logger.debug invoice_params.inspect
    invoice = Invoice.new(invoice_params)
    if invoice.save!
      render json: invoice, status: 201
    else
      render json: { errors: invoice.errors }, status: 422
    end
  end

  def invoice_params
    params.require(:invoice).permit(:total_amount,:balance_amount, :customer_id, invoice_details_attributes:[:product_id])
  end
end

The raw JSON data passed to the controller :

{
    "invoice":{
        "total_amount":"100",
        "balance_amount":"0",
        "invoice_details_attributes":[{
            "product_id":"4"
        }]
    }
}