Add a single line item to an order

curl --request POST \
  --url https://api.arcuserp.com/v1/orders/{id}/items \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "quantity": 2,
  "variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "sell_rate": 123,
  "unit_price": 123,
  "list_price": 123,
  "notes": "<string>",
  "override": true,
  "override_reason": "<string>"
}
'

import requests

url = "https://api.arcuserp.com/v1/orders/{id}/items"

payload = {
    "product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "quantity": 2,
    "variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "sell_rate": 123,
    "unit_price": 123,
    "list_price": 123,
    "notes": "<string>",
    "override": True,
    "override_reason": "<string>"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    product_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    quantity: 2,
    variant_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    sell_rate: 123,
    unit_price: 123,
    list_price: 123,
    notes: '<string>',
    override: true,
    override_reason: '<string>'
  })
};

fetch('https://api.arcuserp.com/v1/orders/{id}/items', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.arcuserp.com/v1/orders/{id}/items",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'product_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    'quantity' => 2,
    'variant_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    'sell_rate' => 123,
    'unit_price' => 123,
    'list_price' => 123,
    'notes' => '<string>',
    'override' => true,
    'override_reason' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.arcuserp.com/v1/orders/{id}/items"

	payload := strings.NewReader("{\n  \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"quantity\": 2,\n  \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"sell_rate\": 123,\n  \"unit_price\": 123,\n  \"list_price\": 123,\n  \"notes\": \"<string>\",\n  \"override\": true,\n  \"override_reason\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.arcuserp.com/v1/orders/{id}/items")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"quantity\": 2,\n  \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"sell_rate\": 123,\n  \"unit_price\": 123,\n  \"list_price\": 123,\n  \"notes\": \"<string>\",\n  \"override\": true,\n  \"override_reason\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.arcuserp.com/v1/orders/{id}/items")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"quantity\": 2,\n  \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"sell_rate\": 123,\n  \"unit_price\": 123,\n  \"list_price\": 123,\n  \"notes\": \"<string>\",\n  \"override\": true,\n  \"override_reason\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "entity_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "order_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "sku": "<string>",
  "title": "<string>",
  "quantity": 123,
  "quantity_fulfilled": 123,
  "quantity_returned": 123,
  "sell_rate": 123,
  "unit_price": 123,
  "list_price": 123,
  "pricing_rule_adjustment": 123,
  "coupon_adjustment": 123,
  "discount_amount": 123,
  "line_subtotal": 123,
  "tax_amount": 123,
  "line_total": 123,
  "adjustments": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "source_type": "<string>",
      "source_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "source_label": "<string>",
      "per_unit_amount": 123,
      "quantity": 123,
      "line_amount": 123,
      "proration_ratio": 123,
      "applied_at": "2023-11-07T05:31:56Z"
    }
  ],
  "unit_cost": 123,
  "weight": 123,
  "is_tax_exempt": true,
  "product_tax_code": "<string>",
  "sort_order": 123,
  "product_vendor_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "created_at": "2023-11-07T05:31:56Z",
  "updated_at": "2023-11-07T05:31:56Z"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

Orders

Add a single line item to an order

Adds a single line item to an order in draft or confirmed status. Validates that the product is active and belongs to the entity. Runs the pricing engine (qty-break tiers, account pricing level) to compute sell_rate if not overridden. Triggers fullRecalculateOrder after insert. Idempotent via Idempotency-Key. Requires orders:write scope.

A line cannot be added to a CLOSED AR document: a cancelled/voided order, a posted/fulfilled order (returns edit_not_allowed with suggested_action: create_return), or a billed-and-paid / fully-paid order (invoice_status in paid/overdue or payment_status = paid; returns edit_not_allowed with suggested_action: revise_order). To revise a paid order, pass override: true in the body with the orders.revision_override permission; the edit then proceeds, the order’s revision_count increments, and the override is recorded in the activity log. The customer must re-acknowledge the new total.

POST

orders

{id}

items

Add a single line item to an order

curl --request POST \
  --url https://api.arcuserp.com/v1/orders/{id}/items \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "quantity": 2,
  "variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "sell_rate": 123,
  "unit_price": 123,
  "list_price": 123,
  "notes": "<string>",
  "override": true,
  "override_reason": "<string>"
}
'

import requests

url = "https://api.arcuserp.com/v1/orders/{id}/items"

payload = {
    "product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "quantity": 2,
    "variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "sell_rate": 123,
    "unit_price": 123,
    "list_price": 123,
    "notes": "<string>",
    "override": True,
    "override_reason": "<string>"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    product_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    quantity: 2,
    variant_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    sell_rate: 123,
    unit_price: 123,
    list_price: 123,
    notes: '<string>',
    override: true,
    override_reason: '<string>'
  })
};

fetch('https://api.arcuserp.com/v1/orders/{id}/items', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.arcuserp.com/v1/orders/{id}/items",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'product_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    'quantity' => 2,
    'variant_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    'sell_rate' => 123,
    'unit_price' => 123,
    'list_price' => 123,
    'notes' => '<string>',
    'override' => true,
    'override_reason' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.arcuserp.com/v1/orders/{id}/items"

	payload := strings.NewReader("{\n  \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"quantity\": 2,\n  \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"sell_rate\": 123,\n  \"unit_price\": 123,\n  \"list_price\": 123,\n  \"notes\": \"<string>\",\n  \"override\": true,\n  \"override_reason\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.arcuserp.com/v1/orders/{id}/items")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"quantity\": 2,\n  \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"sell_rate\": 123,\n  \"unit_price\": 123,\n  \"list_price\": 123,\n  \"notes\": \"<string>\",\n  \"override\": true,\n  \"override_reason\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.arcuserp.com/v1/orders/{id}/items")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"quantity\": 2,\n  \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"sell_rate\": 123,\n  \"unit_price\": 123,\n  \"list_price\": 123,\n  \"notes\": \"<string>\",\n  \"override\": true,\n  \"override_reason\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "entity_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "order_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "sku": "<string>",
  "title": "<string>",
  "quantity": 123,
  "quantity_fulfilled": 123,
  "quantity_returned": 123,
  "sell_rate": 123,
  "unit_price": 123,
  "list_price": 123,
  "pricing_rule_adjustment": 123,
  "coupon_adjustment": 123,
  "discount_amount": 123,
  "line_subtotal": 123,
  "tax_amount": 123,
  "line_total": 123,
  "adjustments": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "source_type": "<string>",
      "source_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "source_label": "<string>",
      "per_unit_amount": 123,
      "quantity": 123,
      "line_amount": 123,
      "proration_ratio": 123,
      "applied_at": "2023-11-07T05:31:56Z"
    }
  ],
  "unit_cost": 123,
  "weight": 123,
  "is_tax_exempt": true,
  "product_tax_code": "<string>",
  "sort_order": 123,
  "product_vendor_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "created_at": "2023-11-07T05:31:56Z",
  "updated_at": "2023-11-07T05:31:56Z"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

{
  "error": "not_found",
  "code": "not_found",
  "type": "not_found",
  "hint": "The requested order does not exist or does not belong to this entity.",
  "param": "expand[0]",
  "required": "accounts:read",
  "request_id": "req_abc123"
}

Authorizations

Authorization

string

header

required

API key issued per entity via Settings > Developers > API Keys. Each key carries scopes (e.g. orders:read, products:write). Bearer token format: Authorization: Bearer ark_live_ent_Test keys use ark_test_ent_. Both are issued per entity via Settings > Developers > API Keys.

Headers

Idempotency-Key

string

Client-generated unique key for idempotent POST/PATCH/DELETE operations. Alias for the Idempotency parameter. Max 255 chars. On retry with the same key, the original response is returned without re-executing the operation. Keys expire after 24 hours.

Maximum string length: 255

Path Parameters

string<uuid>

required

Body

application/json

product_id

string<uuid>

required

quantity

integer

required

Required range: x >= 1

variant_id

string<uuid>

sell_rate

number

Override unit price (canonical Arcus field).

unit_price

number

Alias of sell_rate (Stripe/Shopify convention). Either name accepted. Both with different values returns 400; negative/zero returns 422. When applied price differs from catalog list_price, response carries warnings array entries plus emits order.price_override audit row.

list_price

number

notes

string

override

boolean

Set true (with the orders.revision_override permission) to revise a paid/billed order by adding this line. Without it, a paid/billed order returns 422 edit_not_allowed (suggested_action revise_order).

override_reason

string

Optional reason recorded in the audit log when override is used.

Response

Added order item. Response includes unit_price alias of sell_rate. When override detected, response also carries warnings array entries (item, code price_override, product_id, catalog_price, applied_price, delta).

A line item on an order. Sub-resource of Order.

string<uuid>

entity_id

string<uuid>

read-only

Multi-tenant scoping column (Layer 1 isolation). Set automatically from the parent orders.entity_id and enforced by Postgres trigger trg_order_items_entity_parity (P0-ENTITY-ID-CHILD-TABLES, 2026-05-18). Cross-tenant writes are rejected at the database layer.

order_id

string<uuid>

product_id

string<uuid> | null

variant_id

string<uuid> | null

sku

string | null

title

string

quantity

integer

quantity_fulfilled

integer

read-only

quantity_returned

integer

read-only

sell_rate

number

Canonical Arcus per-unit price column (matches order_items.sell_rate).

unit_price

number

Public-API alias of sell_rate (Stripe/Shopify/QuickBooks convention). Always populated on read; equal to sell_rate. Set per NEW-GAP-API-V1-CALLER-UNIT-PRICE-SILENTLY-OVERRIDDEN 2026-05-17 closure.

list_price

number

pricing_rule_adjustment

number

read-only

Per-unit pricing-rule savings (list_price minus sell_rate, positive magnitude). Already baked into sell_rate (and therefore line_subtotal) per ASC 606 transaction-price pricing; surfaced for the gross-to-net bridge display, never re-subtracted.

coupon_adjustment

number

read-only

Per-line allocated coupon/order-level discount (signed; negative for a discount). Reflected in line_subtotal.

discount_amount

number

line_subtotal

number

read-only

tax_amount

number

read-only

line_total

number

read-only

adjustments

object[]

read-only

Per-line, per-source adjustment breakdown from order_item_adjustments (the canonical SSOT). Each entry attributes a signed line_amount to a source (pricing_rule | order_adjustment | coupon | manual_line_override | return_refund_adjust | restocking_fee). Empty array for lines with no allocations (and on legacy orders predating the writer). Industry parity: Shopify Admin GraphQL LineItem.discountAllocations[].

Show child attributes

unit_cost

number | null

weight

number | null

is_tax_exempt

boolean

product_tax_code

string | null

sort_order

integer

product_vendor_id

string<uuid> | null

For purchase_order document_type lines only: exact product_vendors row this line is bound to (NEW-GAP-ORDER-ITEMS-PRODUCT-VENDOR-ID-PROVENANCE, 2026-05-14). NULL for legacy PO lines and all non-PO doc types; PDF falls back to the deterministic default-vendor-part pick.

created_at

string<date-time>

read-only

updated_at

string<date-time>

read-only

List line items on an order (with optional packable view)Add up to 250 line items in a single atomic transaction