curl --request POST \
--url https://api.arcuserp.com/v1/purchase-orders/{id}/items \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '
{
"product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"quantity": 1.0001,
"variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"unit_cost": 123,
"purchase_policy_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"sort_order": 123,
"product_vendor_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}
'import requests
url = "https://api.arcuserp.com/v1/purchase-orders/{id}/items"
payload = {
"product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"quantity": 1.0001,
"variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"unit_cost": 123,
"purchase_policy_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"sort_order": 123,
"product_vendor_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}
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: 1.0001,
variant_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
unit_cost: 123,
purchase_policy_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
sort_order: 123,
product_vendor_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a'
})
};
fetch('https://api.arcuserp.com/v1/purchase-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/purchase-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' => 1.0001,
'variant_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
'unit_cost' => 123,
'purchase_policy_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
'sort_order' => 123,
'product_vendor_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a'
]),
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/purchase-orders/{id}/items"
payload := strings.NewReader("{\n \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"quantity\": 1.0001,\n \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"unit_cost\": 123,\n \"purchase_policy_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"sort_order\": 123,\n \"product_vendor_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\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/purchase-orders/{id}/items")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"quantity\": 1.0001,\n \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"unit_cost\": 123,\n \"purchase_policy_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"sort_order\": 123,\n \"product_vendor_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\n}")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.arcuserp.com/v1/purchase-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\": 1.0001,\n \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"unit_cost\": 123,\n \"purchase_policy_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"sort_order\": 123,\n \"product_vendor_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\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,
"received_floor": 123,
"line_editability": {
"qty": {
"allowed": true,
"reason": "po_pending_approval_edit_locked",
"floor": 123
},
"unit_cost": {
"allowed": true,
"reason": "po_pending_approval_edit_locked",
"warn_received_qty": 123
},
"delete": {
"allowed": true,
"reason": "po_pending_approval_edit_locked"
},
"notes": {
"allowed": true,
"reason": "po_pending_approval_edit_locked"
}
},
"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"
}"<unknown>"Add a purchase order line
Adds a line item to a purchase order in draft or open status, merging the quantity onto an existing line for the same product and variant rather than creating a duplicate; when unit_cost is omitted, the best applicable purchase pricing policy is applied automatically. Requires purchasing:write scope, and is refused with 422 for kit products, variant-parent products without a specific variant_id, or a PO awaiting approval.
curl --request POST \
--url https://api.arcuserp.com/v1/purchase-orders/{id}/items \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '
{
"product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"quantity": 1.0001,
"variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"unit_cost": 123,
"purchase_policy_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"sort_order": 123,
"product_vendor_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}
'import requests
url = "https://api.arcuserp.com/v1/purchase-orders/{id}/items"
payload = {
"product_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"quantity": 1.0001,
"variant_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"unit_cost": 123,
"purchase_policy_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
"sort_order": 123,
"product_vendor_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}
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: 1.0001,
variant_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
unit_cost: 123,
purchase_policy_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
sort_order: 123,
product_vendor_id: '3c90c3cc-0d44-4b50-8888-8dd25736052a'
})
};
fetch('https://api.arcuserp.com/v1/purchase-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/purchase-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' => 1.0001,
'variant_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
'unit_cost' => 123,
'purchase_policy_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
'sort_order' => 123,
'product_vendor_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a'
]),
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/purchase-orders/{id}/items"
payload := strings.NewReader("{\n \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"quantity\": 1.0001,\n \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"unit_cost\": 123,\n \"purchase_policy_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"sort_order\": 123,\n \"product_vendor_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\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/purchase-orders/{id}/items")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"product_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"quantity\": 1.0001,\n \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"unit_cost\": 123,\n \"purchase_policy_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"sort_order\": 123,\n \"product_vendor_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\n}")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.arcuserp.com/v1/purchase-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\": 1.0001,\n \"variant_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"unit_cost\": 123,\n \"purchase_policy_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n \"sort_order\": 123,\n \"product_vendor_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\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,
"received_floor": 123,
"line_editability": {
"qty": {
"allowed": true,
"reason": "po_pending_approval_edit_locked",
"floor": 123
},
"unit_cost": {
"allowed": true,
"reason": "po_pending_approval_edit_locked",
"warn_received_qty": 123
},
"delete": {
"allowed": true,
"reason": "po_pending_approval_edit_locked"
},
"notes": {
"allowed": true,
"reason": "po_pending_approval_edit_locked"
}
},
"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"
}"<unknown>"Authorizations
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
Optional idempotency key for safe retries (Stripe-style).
255Path Parameters
Body
The product (SKU) to add. Cannot be a kit. If the product has variants, variant_id is also required.
Quantity ordered. Must be positive.
x >= 0.0001Optional variant of product_id.
Optional unit cost override. Omit to auto-apply best purchase-pricing policy.
Optional pricing policy id to lock against (for audit trail).
Optional sort order on the PO; defaults to 0.
Optional pointer at the exact product_vendors row this PO line is bound
to. Persisted on order_items.product_vendor_id so the PO PDF / receiving
/ vendor email surface the operator-chosen vendor-part deterministically
when a product has 2+ product_vendors rows for the same vendor.
Validated against this entity (product_vendors -> products.entity_id) AND
the line's (product_id, vendor_id); mismatched ids reject with 400
(invalid_product_vendor_id / product_vendor_product_mismatch /
product_vendor_vendor_mismatch). Omit to let the PO PDF fall back to the
deterministic LATERAL LIMIT 1 default-vendor-part pick.
Response
Line item added (or merged into existing line of same product+variant).
A line item on an order. Sub-resource of Order.
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.
PURCHASE-ORDER lines only. The lowest quantity this line may be reduced to: the SAFEST of the line's quantity_fulfilled and its receipted-plus-damaged total, clamped at 0. The two sources disagree on migrated rows and on rows whose receipt was undone, so the maximum of both is used -- it can only ever refuse a reduction that either source forbids.
PURCHASE-ORDER lines only. Per-field verdicts from the same predicate the write handlers enforce, so a client never has to restate the stage rules.
Show child attributes
Show child attributes
Canonical Arcus per-unit price column (matches order_items.sell_rate).
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.
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.
Per-line allocated coupon/order-level discount (signed; negative for a discount). Reflected in line_subtotal.
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
Show child attributes
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.
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