refactor: Replace hardcoded billing data seeding with plugin-configurable collection overrides

- Remove `seedBillingData` function for sample data creation
- Update refunds, invoices, and payments collections to use pluginConfig for dynamic overrides
- Introduce utility functions like `extractSlug` for customizable collection slugs
- Streamline customer relation and data extractor logic across collections

dev/payload.config.ts

@@ -2,12 +2,12 @@ import { sqliteAdapter } from '@payloadcms/db-sqlite'
 import { lexicalEditor } from '@payloadcms/richtext-lexical'
 import path from 'path'
 import { buildConfig } from 'payload'
-import { billingPlugin, defaultCustomerInfoExtractor } from '../dist/index.js'
 import sharp from 'sharp'
 import { fileURLToPath } from 'url'
 
 import { testEmailAdapter } from './helpers/testEmailAdapter'
 import { seed } from './seed'
+import billingPlugin from '../src/plugin'
 
 const filename = fileURLToPath(import.meta.url)
 const dirname = path.dirname(filename)
@@ -56,27 +56,29 @@ const buildConfigWithSQLite = () => {
         },
         collections: {
           payments: 'payments',
-          customers: 'customers',
           invoices: 'invoices',
           refunds: 'refunds',
-          // customerRelation: false, // Set to false to disable customer relationship in invoices
-          // customerRelation: 'clients', // Or set to a custom collection slug
         },
-        // Use the default extractor for the built-in customer collection
-        customerInfoExtractor: defaultCustomerInfoExtractor,
-        // Or provide a custom extractor for your own customer collection structure:
+        // // Customer relationship configuration
+        // customerRelationSlug: 'customers', // Use 'customers' collection for relationship
+        // // customerRelationSlug: false,     // Or set to false to disable customer relationship
+        // // customerRelationSlug: 'clients', // Or use a custom collection slug
+        //
+        // // Provide an extractor for your customer collection structure:
         // customerInfoExtractor: (customer) => ({
-        //   name: customer.fullName,
-        //   email: customer.contactEmail,
-        //   phone: customer.phoneNumber,
-        //   company: customer.companyName,
-        //   taxId: customer.vatNumber,
-        //   billingAddress: {
-        //     line1: customer.billing.street,
-        //     city: customer.billing.city,
-        //     postalCode: customer.billing.zip,
-        //     country: customer.billing.countryCode,
-        //   }
+        //   name: customer.name || '',
+        //   email: customer.email || '',
+        //   phone: customer.phone,
+        //   company: customer.company,
+        //   taxId: customer.taxId,
+        //   billingAddress: customer.address ? {
+        //     line1: customer.address.line1 || '',
+        //     line2: customer.address.line2,
+        //     city: customer.address.city || '',
+        //     state: customer.address.state,
+        //     postalCode: customer.address.postalCode || '',
+        //     country: customer.address.country || '',
+        //   } : undefined,
         // })
       }),
     ],

dev/seed.ts

@@ -26,124 +26,4 @@ export const seed = async (payload: Payload) => {
 
 async function seedBillingData(payload: Payload): Promise<void> {
   payload.logger.info('Seeding billing sample data...')
-
-  try {
-    // Check if we already have sample data
-    const existingCustomers = await payload.count({
-      collection: 'customers',
-      where: {
-        email: {
-          equals: 'john.doe@example.com',
-        },
-      },
-    })
-
-    if (existingCustomers.totalDocs > 0) {
-      payload.logger.info('Sample billing data already exists, skipping seed')
-      return
-    }
-
-    // Create a sample customer
-    const customer = await payload.create({
-      collection: 'customers',
-      data: {
-        email: 'john.doe@example.com',
-        name: 'John Doe',
-        phone: '+1-555-0123',
-        address: {
-          line1: '123 Main St',
-          city: 'New York',
-          state: 'NY',
-          postal_code: '10001',
-          country: 'US'
-        },
-        metadata: {
-          source: 'seed',
-          created_by: 'system'
-        }
-      }
-    })
-
-    payload.logger.info(`Created sample customer: ${customer.id}`)
-
-    // Create a sample invoice
-    const invoice = await payload.create({
-      collection: 'invoices',
-      data: {
-        number: 'INV-001-SAMPLE',
-        customer: customer.id,
-        currency: 'USD',
-        items: [
-          {
-            description: 'Web Development Services',
-            quantity: 10,
-            unitAmount: 5000, // $50.00 per hour
-            totalAmount: 50000 // $500.00 total
-          },
-          {
-            description: 'Design Consultation',
-            quantity: 2,
-            unitAmount: 7500, // $75.00 per hour
-            totalAmount: 15000 // $150.00 total
-          }
-        ],
-        subtotal: 65000, // $650.00
-        taxAmount: 5200, // $52.00 (8% tax)
-        amount: 70200, // $702.00 total
-        status: 'open',
-        dueDate: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000).toISOString(), // 30 days from now
-        notes: 'Payment terms: Net 30 days. This is sample data for development.',
-        metadata: {
-          project: 'website-redesign',
-          billable_hours: 12,
-          sample: true
-        }
-      }
-    })
-
-    payload.logger.info(`Created sample invoice: ${invoice.number}`)
-
-    // Create a sample payment using test provider
-    const payment = await payload.create({
-      collection: 'payments',
-      data: {
-        provider: 'test',
-        providerId: `test_pay_sample_${Date.now()}`,
-        status: 'succeeded',
-        amount: 70200, // $702.00
-        currency: 'USD',
-        description: `Sample payment for invoice ${invoice.number}`,
-        customer: customer.id,
-        invoice: invoice.id,
-        metadata: {
-          invoice_number: invoice.number,
-          payment_method: 'test_card',
-          sample: true
-        },
-        providerData: {
-          testMode: true,
-          simulatedPayment: true,
-          autoCompleted: true
-        }
-      }
-    })
-
-    payload.logger.info(`Created sample payment: ${payment.id}`)
-
-    // Update invoice status to paid
-    await payload.update({
-      collection: 'invoices',
-      id: invoice.id,
-      data: {
-        status: 'paid',
-        payment: payment.id,
-        paidAt: new Date().toISOString()
-      }
-    })
-
-    payload.logger.info('Billing sample data seeded successfully!')
-
-  } catch (error) {
-    payload.logger.error('Error seeding billing data:', error)
-  }
 }

src/collections/invoices.ts

@@ -3,30 +3,16 @@ import {
   CollectionAfterChangeHook,
   CollectionBeforeChangeHook,
   CollectionBeforeValidateHook,
-  CollectionConfig,
+  CollectionConfig, Field,
 } from 'payload'
-import { CustomerInfoExtractor } from '@/plugin/config'
+import { BillingPluginConfig, CustomerInfoExtractor, defaults } from '@/plugin/config'
 import { Invoice } from '@/plugin/types'
+import { extractSlug } from '@/plugin/utils'
 
-export function createInvoicesCollection(
-  slug: string = 'invoices',
-  customerCollectionSlug?: string,
-  customerInfoExtractor?: CustomerInfoExtractor
-): CollectionConfig {
-  return {
-    slug,
-    access: {
-      create: ({ req: { user } }: AccessArgs) => !!user,
-      delete: ({ req: { user } }: AccessArgs) => !!user,
-      read: ({ req: { user } }: AccessArgs) => !!user,
-      update: ({ req: { user } }: AccessArgs) => !!user,
-    },
-    admin: {
-      defaultColumns: ['number', 'customerInfo.name', 'status', 'amount', 'currency', 'dueDate'],
-      group: 'Billing',
-      useAsTitle: 'number',
-    },
-    fields: [
+export function createInvoicesCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
+  const {customerRelationSlug, customerInfoExtractor} = pluginConfig
+  const overrides = typeof pluginConfig.collections?.invoices === 'object' ? pluginConfig.collections?.invoices : {}
+  let fields: Field[] = [
     {
       name: 'number',
       type: 'text',
@@ -38,14 +24,14 @@ export function createInvoicesCollection(
       unique: true,
     },
     // Optional customer relationship
-      ...(customerCollectionSlug ? [{
+    ...(customerRelationSlug ? [{
       name: 'customer',
       type: 'relationship' as const,
       admin: {
         position: 'sidebar' as const,
         description: 'Link to customer record (optional)',
       },
-        relationTo: customerCollectionSlug as any,
+      relationTo: pluginConfig.customerRelationSlug as never,
       required: false,
     }] : []),
     // Basic customer info fields (embedded)
@@ -53,10 +39,10 @@ export function createInvoicesCollection(
       name: 'customerInfo',
       type: 'group',
       admin: {
-          description: customerCollectionSlug && customerInfoExtractor
+        description: customerRelationSlug && customerInfoExtractor
           ? 'Customer billing information (auto-populated from customer relationship)'
           : 'Customer billing information',
-          readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+        readOnly: !!(customerRelationSlug && customerInfoExtractor),
       },
       fields: [
         {
@@ -64,25 +50,25 @@ export function createInvoicesCollection(
           type: 'text',
           admin: {
             description: 'Customer name',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
-            required: !customerCollectionSlug || !customerInfoExtractor,
+          required: !customerRelationSlug || !customerInfoExtractor,
         },
         {
           name: 'email',
           type: 'email',
           admin: {
             description: 'Customer email address',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
-            required: !customerCollectionSlug || !customerInfoExtractor,
+          required: !customerRelationSlug || !customerInfoExtractor,
         },
         {
           name: 'phone',
           type: 'text',
           admin: {
             description: 'Customer phone number',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
         },
         {
@@ -90,7 +76,7 @@ export function createInvoicesCollection(
           type: 'text',
           admin: {
             description: 'Company name (optional)',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
         },
         {
@@ -98,7 +84,7 @@ export function createInvoicesCollection(
           type: 'text',
           admin: {
             description: 'Tax ID or VAT number',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
         },
       ],
@@ -107,10 +93,10 @@ export function createInvoicesCollection(
       name: 'billingAddress',
       type: 'group',
       admin: {
-          description: customerCollectionSlug && customerInfoExtractor
+        description: customerRelationSlug && customerInfoExtractor
           ? 'Billing address (auto-populated from customer relationship)'
           : 'Billing address',
-          readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+        readOnly: !!(customerRelationSlug && customerInfoExtractor),
       },
       fields: [
         {
@@ -118,32 +104,32 @@ export function createInvoicesCollection(
           type: 'text',
           admin: {
             description: 'Address line 1',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
-            required: !customerCollectionSlug || !customerInfoExtractor,
+          required: !customerRelationSlug || !customerInfoExtractor,
         },
         {
           name: 'line2',
           type: 'text',
           admin: {
             description: 'Address line 2',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
         },
         {
           name: 'city',
           type: 'text',
           admin: {
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
-            required: !customerCollectionSlug || !customerInfoExtractor,
+          required: !customerRelationSlug || !customerInfoExtractor,
         },
         {
           name: 'state',
           type: 'text',
           admin: {
             description: 'State or province',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
         },
         {
@@ -151,19 +137,19 @@ export function createInvoicesCollection(
           type: 'text',
           admin: {
             description: 'Postal or ZIP code',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
-            required: !customerCollectionSlug || !customerInfoExtractor,
+          required: !customerRelationSlug || !customerInfoExtractor,
         },
         {
           name: 'country',
           type: 'text',
           admin: {
             description: 'Country code (e.g., US, GB)',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
           },
           maxLength: 2,
-            required: !customerCollectionSlug || !customerInfoExtractor,
+          required: !customerRelationSlug || !customerInfoExtractor,
         },
       ],
     },
@@ -305,7 +291,24 @@ export function createInvoicesCollection(
         description: 'Additional invoice metadata',
       },
     },
-    ],
+  ]
+  if (overrides?.fields) {
+    fields = overrides.fields({defaultFields: fields})
+  }
+  return {
+    slug: extractSlug(pluginConfig.collections?.invoices || defaults.invoicesCollection),
+    access: {
+      create: ({ req: { user } }: AccessArgs) => !!user,
+      delete: ({ req: { user } }: AccessArgs) => !!user,
+      read: ({ req: { user } }: AccessArgs) => !!user,
+      update: ({ req: { user } }: AccessArgs) => !!user,
+    },
+    admin: {
+      defaultColumns: ['number', 'customerInfo.name', 'status', 'amount', 'currency', 'dueDate'],
+      group: 'Billing',
+      useAsTitle: 'number',
+    },
+    fields,
     hooks: {
       afterChange: [
         ({ doc, operation, req }) => {
@@ -317,7 +320,7 @@ export function createInvoicesCollection(
       beforeChange: [
         async ({ data, operation, req, originalDoc }) => {
           // Sync customer info from relationship if extractor is provided
-          if (customerCollectionSlug && customerInfoExtractor && data.customer) {
+          if (customerRelationSlug && customerInfoExtractor && data.customer) {
             // Check if customer changed or this is a new invoice
             const customerChanged = operation === 'create' ||
               (originalDoc && originalDoc.customer !== data.customer)
@@ -326,8 +329,8 @@ export function createInvoicesCollection(
               try {
                 // Fetch the customer data
                 const customer = await req.payload.findByID({
-                  collection: customerCollectionSlug as any,
-                  id: data.customer,
+                  collection: customerRelationSlug as never,
+                  id: data.customer as never,
                 })
 
                 // Extract customer info using the provided callback
@@ -386,18 +389,18 @@ export function createInvoicesCollection(
           if (!data) return
 
           // If using extractor, customer relationship is required
-          if (customerCollectionSlug && customerInfoExtractor && !data.customer) {
+          if (customerRelationSlug && customerInfoExtractor && !data.customer) {
             throw new Error('Please select a customer')
           }
 
           // If not using extractor but have customer collection, either relationship or info is required
-          if (customerCollectionSlug && !customerInfoExtractor &&
+          if (customerRelationSlug && !customerInfoExtractor &&
               !data.customer && (!data.customerInfo?.name || !data.customerInfo?.email)) {
             throw new Error('Either select a customer or provide customer information')
           }
 
           // If no customer collection, ensure customer info is provided
-          if (!customerCollectionSlug && (!data.customerInfo?.name || !data.customerInfo?.email)) {
+          if (!customerRelationSlug && (!data.customerInfo?.name || !data.customerInfo?.email)) {
             throw new Error('Customer name and email are required')
           }
 

src/collections/payments.ts

@@ -1,21 +1,12 @@
-import { AccessArgs, CollectionAfterChangeHook, CollectionBeforeChangeHook, CollectionConfig } from 'payload'
-import { Payment } from '@/plugin/types'
+import type { AccessArgs, CollectionBeforeChangeHook, CollectionConfig, Field } from 'payload'
+import type { Payment } from '@/plugin/types'
+import type { BillingPluginConfig} from '@/plugin/config';
+import { defaults } from '@/plugin/config'
+import { extractSlug } from '@/plugin/utils'
 
-export function createPaymentsCollection(slug: string = 'payments'): CollectionConfig {
-  return {
-    slug,
-    access: {
-      create: ({ req: { user } }: AccessArgs) => !!user,
-      delete: ({ req: { user } }: AccessArgs) => !!user,
-      read: ({ req: { user } }: AccessArgs) => !!user,
-      update: ({ req: { user } }: AccessArgs) => !!user,
-    },
-    admin: {
-      defaultColumns: ['id', 'provider', 'status', 'amount', 'currency', 'createdAt'],
-      group: 'Billing',
-      useAsTitle: 'id',
-    },
-    fields: [
+export function createPaymentsCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
+  const overrides = typeof pluginConfig.collections?.payments === 'object' ? pluginConfig.collections?.payments : {}
+  let fields: Field[] = [
     {
       name: 'provider',
       type: 'select',
@@ -81,14 +72,6 @@ export function createPaymentsCollection(slug: string = 'payments'): CollectionC
         description: 'Payment description',
       },
     },
-      {
-        name: 'customer',
-        type: 'relationship',
-        admin: {
-          position: 'sidebar',
-        },
-        relationTo: 'customers',
-      },
     {
       name: 'invoice',
       type: 'relationship',
@@ -122,7 +105,25 @@ export function createPaymentsCollection(slug: string = 'payments'): CollectionC
       hasMany: true,
       relationTo: 'refunds',
     },
-    ],
+  ]
+  if (overrides?.fields) {
+    fields = overrides?.fields({defaultFields: fields})
+  }
+  return {
+    slug: extractSlug(pluginConfig.collections?.payments || defaults.paymentsCollection),
+    access: overrides?.access || {
+      create: ({ req: { user } }: AccessArgs) => !!user,
+      delete: ({ req: { user } }: AccessArgs) => !!user,
+      read: ({ req: { user } }: AccessArgs) => !!user,
+      update: ({ req: { user } }: AccessArgs) => !!user,
+    },
+    admin: {
+      defaultColumns: ['id', 'provider', 'status', 'amount', 'currency', 'createdAt'],
+      group: 'Billing',
+      useAsTitle: 'id',
+      ...overrides?.admin
+    },
+    fields,
     hooks: {
       beforeChange: [
         ({ data, operation }) => {

src/collections/refunds.ts

@@ -1,16 +1,12 @@
-import type { CollectionConfig } from 'payload'
+import type { AccessArgs, CollectionConfig } from 'payload'
+import { BillingPluginConfig, defaults } from '@/plugin/config'
+import { extractSlug } from '@/plugin/utils'
 
-import type {
-  AccessArgs,
-  CollectionAfterChangeHook,
-  CollectionBeforeChangeHook,
-  RefundData,
-  RefundDocument
-} from '../types/payload'
-
-export function createRefundsCollection(slug: string = 'refunds'): CollectionConfig {
+export function createRefundsCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
+  const overrides = typeof pluginConfig.collections?.invoices === 'object' ? pluginConfig.collections?.invoices : {}
+  // TODO: finish collection overrides
   return {
-    slug,
+    slug: extractSlug(pluginConfig.collections?.refunds || defaults.refundsCollection),
     access: {
       create: ({ req: { user } }: AccessArgs) => !!user,
       delete: ({ req: { user } }: AccessArgs) => !!user,
@@ -113,7 +109,7 @@ export function createRefundsCollection(slug: string = 'refunds'): CollectionCon
     ],
     hooks: {
       afterChange: [
-        async ({ doc, operation, req }: CollectionAfterChangeHook<RefundDocument>) => {
+        async ({ doc, operation, req }) => {
           if (operation === 'create') {
             req.payload.logger.info(`Refund created: ${doc.id} for payment: ${doc.payment}`)
 
@@ -129,7 +125,7 @@ export function createRefundsCollection(slug: string = 'refunds'): CollectionCon
                 id: typeof doc.payment === 'string' ? doc.payment : doc.payment.id,
                 collection: 'payments',
                 data: {
-                  refunds: [...refundIds, doc.id as any],
+                  refunds: [...refundIds, doc.id],
                 },
               })
             } catch (error) {
@@ -139,7 +135,7 @@ export function createRefundsCollection(slug: string = 'refunds'): CollectionCon
         },
       ],
       beforeChange: [
-        ({ data, operation }: CollectionBeforeChangeHook<RefundData>) => {
+        ({ data, operation }) => {
           if (operation === 'create') {
             // Validate amount format
             if (data.amount && !Number.isInteger(data.amount)) {

src/index.ts

@@ -1,3 +1,2 @@
-export * from './types'
 
 

src/plugin/config.ts

@@ -1,6 +1,11 @@
+import { CollectionConfig } from 'payload'
+import { FieldsOverride } from '@/plugin/utils'
 
 export const defaults = {
-  paymentsCollection: 'payments'
+  paymentsCollection: 'payments',
+  invoicesCollection: 'invoices',
+  refundsCollection: 'refunds',
+  customerRelationSlug: 'customer'
 }
 
 // Provider configurations
@@ -51,13 +56,12 @@ export interface BillingPluginConfig {
     dashboard?: boolean
   }
   collections?: {
-    customerRelation?: boolean | string // false to disable, string for custom collection slug
-    customers?: string
-    invoices?: string
-    payments?: string
-    refunds?: string
+    invoices?: string | (Partial<CollectionConfig> & {fields?: FieldsOverride})
+    payments?: string | (Partial<CollectionConfig> & {fields?: FieldsOverride})
+    refunds?: string | (Partial<CollectionConfig> & {fields?: FieldsOverride})
   }
   customerInfoExtractor?: CustomerInfoExtractor // Callback to extract customer info from relationship
+  customerRelationSlug?: string // Customer collection slug for relationship
   disabled?: boolean
   providers?: {
     mollie?: MollieConfig

src/plugin/index.ts

@@ -1,6 +1,6 @@
 import type { Config } from 'payload'
 import { createInvoicesCollection, createPaymentsCollection, createRefundsCollection } from '@/collections'
-import { BillingPluginConfig } from '@/plugin/config'
+import type { BillingPluginConfig } from '@/plugin/config'
 
 export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config: Config): Config => {
   if (pluginConfig.disabled) {
@@ -12,16 +12,10 @@ export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config
     config.collections = []
   }
 
-  const customerSlug = pluginConfig.collections?.customers || 'customers'
-
   config.collections.push(
-    createPaymentsCollection(pluginConfig.collections?.payments || 'payments'),
-    createInvoicesCollection(
-      pluginConfig.collections?.invoices || 'invoices',
-      pluginConfig.collections?.customerRelation !== false ? customerSlug : undefined,
-      pluginConfig.customerInfoExtractor
-    ),
-    createRefundsCollection(pluginConfig.collections?.refunds || 'refunds'),
+    createPaymentsCollection(pluginConfig),
+    createInvoicesCollection(pluginConfig),
+    createRefundsCollection(pluginConfig),
   )
 
   // Initialize endpoints

src/plugin/types.ts

@@ -1,7 +1,58 @@
-import { Customer, Refund } from '../../dev/payload-types'
 
 export type Id = string | number
 
+export interface Refund {
+  id: number;
+  /**
+   * The refund ID from the payment provider
+   */
+  providerId: string;
+  payment: number | Payment;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled';
+  /**
+   * Refund amount in cents
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Reason for the refund
+   */
+  reason?: ('duplicate' | 'fraudulent' | 'requested_by_customer' | 'other') | null;
+  /**
+   * Additional details about the refund
+   */
+  description?: string | null;
+  /**
+   * Additional refund metadata
+   */
+  metadata?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
+
 export interface Payment {
   id: Id;
   provider: 'stripe' | 'mollie' | 'test';
@@ -22,7 +73,6 @@ export interface Payment {
    * Payment description
    */
   description?: string | null;
-  customer?: (Id | null) | Customer;
   invoice?: (Id | null) | Invoice;
   /**
    * Additional metadata for the payment
@@ -53,7 +103,7 @@ export interface Payment {
   createdAt: string;
 }
 
-export interface Invoice {
+export interface Invoice<TCustomer = unknown> {
   id: Id;
   /**
    * Invoice number (e.g., INV-001)
@@ -62,7 +112,7 @@ export interface Invoice {
   /**
    * Link to customer record (optional)
    */
-  customer?: (Id | null) | Customer;
+  customer?: (Id | null) | TCustomer;
   /**
    * Customer billing information (auto-populated from customer relationship)
    */
@@ -166,3 +216,4 @@ export interface Invoice {
   updatedAt: string;
   createdAt: string;
 }
+

src/plugin/utils.ts

@@ -0,0 +1,5 @@
+import type { CollectionConfig, Field } from 'payload'
+
+export type FieldsOverride = (args: { defaultFields: Field[] }) => Field[]
+
+export const extractSlug = (arg: string | Partial<CollectionConfig>) => typeof arg === 'string' ? arg : arg.slug!