npx create-payload-app@latest my-app
cd my-app
pnpm dev

import { buildConfig } from "payload";
import { mongooseAdapter } from "@payloadcms/db-mongodb";
import { lexicalEditor } from "@payloadcms/richtext-lexical";
import path from "path";
import { fileURLToPath } from "url";

const filename = fileURLToPath(import.meta.url);
const dirname = path.dirname(filename);

export default buildConfig({
  admin: {
    user: "users",
    importMap: {
      baseDir: path.resolve(dirname),
    },
  },
  collections: [Users, Media],
  editor: lexicalEditor(),
  secret: process.env.PAYLOAD_SECRET,
  typescript: {
    outputFile: path.resolve(dirname, "payload-types.ts"),
  },
  db: mongooseAdapter({
    url: process.env.DATABASE_URL,
  }),
});

import type { CollectionConfig } from "payload";

export const Posts: CollectionConfig = {
  slug: "posts",
  admin: {
    useAsTitle: "title",
    defaultColumns: ["title", "author", "status", "createdAt"],
  },
  fields: [
    { name: "title", type: "text", required: true },
    { name: "slug", type: "text", unique: true, index: true },
    { name: "content", type: "richText" },
    { name: "author", type: "relationship", relationTo: "users" },
  ],
  timestamps: true,
};

// Text field
{ name: 'title', type: 'text', required: true }

// Relationship
{ name: 'author', type: 'relationship', relationTo: 'users', required: true }

// Rich text
{ name: 'content', type: 'richText', required: true }

// Select
{ name: 'status', type: 'select', options: ['draft', 'published'], defaultValue: 'draft' }

// Upload
{ name: 'image', type: 'upload', relationTo: 'media' }

export const Posts: CollectionConfig = {
  slug: "posts",
  hooks: {
    beforeChange: [
      async ({ data, operation }) => {
        if (operation === "create") {
          data.slug = slugify(data.title);
        }
        return data;
      },
    ],
  },
  fields: [{ name: "title", type: "text" }],
};

import type { Access } from "payload";
import type { User } from "@/payload-types";

// Type-safe access control
export const adminOnly: Access = ({ req }) => {
  const user = req.user as User;
  return user?.roles?.includes("admin") || false;
};

// Row-level access control
export const ownPostsOnly: Access = ({ req }) => {
  const user = req.user as User;
  if (!user) return false;
  if (user.roles?.includes("admin")) return true;

  return {
    author: { equals: user.id },
  };
};

// Local API
const posts = await payload.find({
  collection: "posts",
  where: {
    status: { equals: "published" },
    "author.name": { contains: "john" },
  },
  depth: 2,
  limit: 10,
  sort: "-createdAt",
});

// Query with populated relationships
const post = await payload.findByID({
  collection: "posts",
  id: "123",
  depth: 2, // Populates relationships (default is 2)
});
// Returns: { author: { id: "user123", name: "John" } }

// Without depth, relationships return IDs only
const post = await payload.findByID({
  collection: "posts",
  id: "123",
  depth: 0,
});
// Returns: { author: "user123" }

// In API routes (Next.js)
import { getPayload } from 'payload'
import config from '@payload-config'

export async function GET() {
  const payload = await getPayload({ config })

  const posts = await payload.find({
    collection: 'posts',
  })

  return Response.json(posts)
}

// In Server Components
import { getPayload } from 'payload'
import config from '@payload-config'

export default async function Page() {
  const payload = await getPayload({ config })
  const { docs } = await payload.find({ collection: 'posts' })

  return <div>{docs.map(post => <h1 key={post.id}>{post.title}</h1>)}</div>
}

// ✅ Valid: single string
payload.logger.error("Something went wrong");

// ✅ Valid: object with msg and err
payload.logger.error({ msg: "Failed to process", err: error });

// ❌ Invalid: don't pass error as second argument
payload.logger.error("Failed to process", error);

// ❌ Invalid: use `err` not `error`, use `msg` not `message`
payload.logger.error({ message: "Failed", error: error });

// ❌ SECURITY BUG: Passes user but ignores their permissions
await payload.find({
  collection: "posts",
  user: someUser, // Access control is BYPASSED!
});

// ✅ SECURE: Actually enforces the user's permissions
await payload.find({
  collection: "posts",
  user: someUser,
  overrideAccess: false, // REQUIRED for access control
});

// ❌ DATA CORRUPTION RISK: Separate transaction
hooks: {
  afterChange: [
    async ({ doc, req }) => {
      await req.payload.create({
        collection: "audit-log",
        data: { docId: doc.id },
        // Missing req - runs in separate transaction!
      });
    },
  ];
}

// ✅ ATOMIC: Same transaction
hooks: {
  afterChange: [
    async ({ doc, req }) => {
      await req.payload.create({
        collection: "audit-log",
        data: { docId: doc.id },
        req, // Maintains atomicity
      });
    },
  ];
}

// ❌ INFINITE LOOP
hooks: {
  afterChange: [
    async ({ doc, req }) => {
      await req.payload.update({
        collection: "posts",
        id: doc.id,
        data: { views: doc.views + 1 },
        req,
      }); // Triggers afterChange again!
    },
  ];
}

// ✅ SAFE: Use context flag
hooks: {
  afterChange: [
    async ({ doc, req, context }) => {
      if (context.skipHooks) return;

      await req.payload.update({
        collection: "posts",
        id: doc.id,
        data: { views: doc.views + 1 },
        context: { skipHooks: true },
        req,
      });
    },
  ];
}

src/
├── app/
│   ├── (frontend)/
│   │   └── page.tsx
│   └── (payload)/
│       └── admin/[[...segments]]/page.tsx
├── collections/
│   ├── Posts.ts
│   ├── Media.ts
│   └── Users.ts
├── globals/
│   └── Header.ts
├── components/
│   └── CustomField.tsx
├── hooks/
│   └── slugify.ts
└── payload.config.ts

// payload.config.ts
export default buildConfig({
  typescript: {
    outputFile: path.resolve(dirname, "payload-types.ts"),
  },
  // ...
});

// Usage
import type { Post, User } from "@/payload-types";