Issue with setting fields in payload for POST "/v1/invoices" api

Question

I have a query regarding following Magento2 API

POST "V1/invoices"

with payload

{
    "entity": {
        "base_discount_tax_compensation_amount": null,
        "base_shipping_discount_tax_compensation_amnt": null,
        "discount_tax_compensation_amount": null,
        "order_id": 58,
        "shipping_discount_tax_compensation_amount": 0,
        "total_qty": 2,
        "grand_total": 155,
        "subtotal": 150,
        "items": [
            {
                "base_discount_tax_compensation_amount": null,
                "discount_tax_compensation_amount": null,
                "order_item_id": 74,
                "sku": null,
                "qty": 56,
                "row_total": 150,
                "tax_amount": 152,
                "discount_amount": 23,
                "price": 154
            }
        ]
    }
}

Please clarify following points

1. Am I supposed to set fields grand_total, subtotal on body level?

2. Fields qty, row_total, tax_amount, discount_amount inside items array?

These fields are visible on invoice created on Magento2. Attaching screenshot of created invoice below:

OR mentioning order_id and order_item_id should be enough??

OR there is some other way , Please do provide info.

Answer 1

the full json structure for this post you can find it http://devdocs.magento.com/swagger/index.html just click on salesInvoiceRepositoryV1 and then POST /V1/invoices/

i've made a test with the very least values and it created succesfully an nvoice:

{
  "entity": {
    "grandTotal": 54,
    "orderId": 4,
    "totalQty": 1,
    "items": [
      {
        "orderItemId": 5,
        "productId": 156,
        "qty": 1
      }
    ],
    "comments": [],
    "extensionAttributes": {}
  }
}

and got back:

{
  "base_discount_tax_compensation_amount": null,
  "base_shipping_discount_tax_compensation_amnt": null,
  "created_at": "2016-06-17 23:08:48",
  "entity_id": 6,
  "grand_total": 54,
  "discount_tax_compensation_amount": null,
  "increment_id": "000000006",
  "order_id": 4,
  "shipping_discount_tax_compensation_amount": null,
  "total_qty": 1,
  "updated_at": "2016-06-17 23:08:48",
  "items": [
    {
      "base_discount_tax_compensation_amount": null,
      "entity_id": 6,
      "discount_tax_compensation_amount": null,
      "order_item_id": 5,
      "parent_id": 6,
      "product_id": 156,
      "qty": 1,
      "sku": null
    }
  ],
  "comments": [],
  "extension_attributes": []
}

so to answer your questions:

1. as you'll see from the devdocs grand_total and subtotal are the same level with items ( so per invoice and not invoice item)
2. yes to all of them and in my test if order_id or order_item_id where missing i got in exception so these are needed.

at this point is up to you to have consistent values inside grandTotal, etc.