feat: Create payment sessions (#6549)

~~Opening a draft PR to discuss a couple of implementation details that we should align on~~

**What**

Add workflow and API endpoint for creating payment sessions for a payment collection. Endpoint is currently `POST /store/payment-collection/:id/payment-sessions`. I suggested an alternative in a comment below.

Please note, we intentionally do not want to support creating payment sessions in bulk, as this would become a mess when having to manage multiple calls to third-party providers.

packages/medusa/src/api-v2/store/carts/route.ts

@@ -1,22 +1,19 @@
+import { createCartWorkflow } from "@medusajs/core-flows"
+import { CreateCartWorkflowInputDTO } from "@medusajs/types"
+import { remoteQueryObjectFromString } from "@medusajs/utils"
 import {
   AuthenticatedMedusaRequest,
   MedusaResponse,
 } from "../../../types/routing"
-
-import { createCartWorkflow } from "@medusajs/core-flows"
-import { CreateCartWorkflowInputDTO } from "@medusajs/types"
-import { remoteQueryObjectFromString } from "@medusajs/utils"
 import { defaultStoreCartFields } from "../carts/query-config"
 
 export const POST = async (
   req: AuthenticatedMedusaRequest<CreateCartWorkflowInputDTO>,
   res: MedusaResponse
 ) => {
-  const workflowInput = req.validatedBody
-
-  // If the customer is logged in, we auto-assign them to the cart
-  if (req.auth?.actor_id) {
-    workflowInput.customer_id = req.auth.actor_id
+  const workflowInput = {
+    ...req.validatedBody,
+    customer_id: req.auth?.actor_id,
   }
 
   const { result, errors } = await createCartWorkflow(req.scope).run({

packages/medusa/src/api-v2/store/payment-collections/[id]/payment-sessions/middlewares.ts

@@ -0,0 +1,11 @@
+import { transformBody } from "../../../../../api/middlewares"
+import { MiddlewareRoute } from "../../../../../loaders/helpers/routing/types"
+import { StorePostPaymentCollectionsPaymentSessionReq } from "./validators"
+
+export const storeCartRoutesMiddlewares: MiddlewareRoute[] = [
+  {
+    method: ["POST"],
+    matcher: "/store/payment-collections/:id/payment-sessions",
+    middlewares: [transformBody(StorePostPaymentCollectionsPaymentSessionReq)],
+  },
+]

packages/medusa/src/api-v2/store/payment-collections/[id]/payment-sessions/query-config.ts

@@ -0,0 +1,20 @@
+export const defaultStorePaymentCollectionFields = [
+  "id",
+  "currency_code",
+  "amount",
+  "payment_sessions",
+  "payment_sessions.id",
+  "payment_sessions.amount",
+  "payment_sessions.provider_id",
+]
+
+export const defaultStorePaymentCollectionRelations = ["payment_sessions"]
+
+export const allowedStorePaymentCollectionRelations = ["payment_sessions"]
+
+export const retrieveTransformQueryConfig = {
+  defaultFields: defaultStorePaymentCollectionFields,
+  defaultRelations: defaultStorePaymentCollectionRelations,
+  allowedRelations: allowedStorePaymentCollectionRelations,
+  isList: false,
+}

packages/medusa/src/api-v2/store/payment-collections/[id]/payment-sessions/route.ts

@@ -0,0 +1,52 @@
+import { createPaymentSessionsWorkflow } from "@medusajs/core-flows"
+import { remoteQueryObjectFromString } from "@medusajs/utils"
+import {
+  AuthenticatedMedusaRequest,
+  MedusaResponse,
+} from "../../../../../types/routing"
+import { defaultStorePaymentCollectionFields } from "./query-config"
+import { StorePostPaymentCollectionsPaymentSessionReq } from "./validators"
+
+export const POST = async (
+  req: AuthenticatedMedusaRequest<StorePostPaymentCollectionsPaymentSessionReq>,
+  res: MedusaResponse
+) => {
+  const { id } = req.params
+  const { context, provider_id, data } = req.body
+
+  // If the customer is logged in, we auto-assign them to the payment collection
+  if (req.auth?.actor_id) {
+    context.customer = {
+      ...context.customer,
+      id: req.auth.actor_id,
+    }
+  }
+
+  const workflowInput = {
+    payment_collection_id: id,
+    provider_id: provider_id,
+    data,
+    context,
+  }
+
+  const { errors } = await createPaymentSessionsWorkflow(req.scope).run({
+    input: workflowInput as any,
+    throwOnError: false,
+  })
+
+  if (Array.isArray(errors) && errors[0]) {
+    throw errors[0].error
+  }
+
+  const remoteQuery = req.scope.resolve("remoteQuery")
+
+  const query = remoteQueryObjectFromString({
+    entryPoint: "payment_collection",
+    variables: { cart: { id } },
+    fields: defaultStorePaymentCollectionFields,
+  })
+
+  const [result] = await remoteQuery(query)
+
+  res.status(200).json({ payment_collection: result })
+}

packages/medusa/src/api-v2/store/payment-collections/[id]/payment-sessions/validators.ts

@@ -0,0 +1,7 @@
+import { PaymentProviderContext } from "@medusajs/types"
+
+export class StorePostPaymentCollectionsPaymentSessionReq {
+  provider_id: string
+  context?: PaymentProviderContext
+  data?: Record<string, unknown>
+}