// Step 1: Add new entity alongside old
const schema = em({
  // OLD - will be removed later
  posts: entity("posts", {
    title: text().required(),
    content: text(),
  }),
  // NEW - desired name
  articles: entity("articles", {
    title: text().required(),
    content: text(),
  }),
});

// Step 2: Migrate data (run once via script or CLI)
const api = app.getApi();
const oldData = await api.data.readMany("posts", { limit: 10000 });

for (const item of oldData.data) {
  await api.data.createOne("articles", {
    title: item.title,
    content: item.content,
  });
}

// Step 3: Remove old entity from schema
const schema = em({
  articles: entity("articles", {
    title: text().required(),
    content: text(),
  }),
});

# Step 4: Sync with force to drop old table
npx bknd sync --force

// Step 1: Add new field alongside old
const schema = em({
  users: entity("users", {
    name: text(),           // OLD - will be removed
    full_name: text(),      // NEW - desired name
  }),
});

// Step 2: Migrate data
const api = app.getApi();
const users = await api.data.readMany("users", { limit: 10000 });

for (const user of users.data) {
  if (user.name && !user.full_name) {
    await api.data.updateOne("users", user.id, {
      full_name: user.name,
    });
  }
}

// Step 3: Remove old field
const schema = em({
  users: entity("users", {
    full_name: text(),
  }),
});

# Step 4: Sync with force to drop old column
npx bknd sync --force

// Step 1: Add new field with new type
const schema = em({
  products: entity("products", {
    price: text(),            // OLD - string prices
    price_cents: number(),    // NEW - integer cents
  }),
});

// Step 2: Transform and migrate data
const api = app.getApi();
const products = await api.data.readMany("products", { limit: 10000 });

for (const product of products.data) {
  if (product.price && !product.price_cents) {
    const cents = Math.round(parseFloat(product.price) * 100);
    await api.data.updateOne("products", product.id, {
      price_cents: cents,
    });
  }
}

// Step 3: Remove old field, rename new if desired
const schema = em({
  products: entity("products", {
    price_cents: number(),
  }),
});

// Before
entity("users", {
  email: text(),  // Optional
});

// After
entity("users", {
  email: text().required(),  // Now required
});

// Step 1: Fill nulls with default
const api = app.getApi();
const usersWithNull = await api.data.readMany("users", {
  where: { email: { $isnull: true } },
});

for (const user of usersWithNull.data) {
  await api.data.updateOne("users", user.id, {
    email: "unknown@example.com",
  });
}

// Step 2: Now safely add .required()

// Before
entity("users", {
  username: text(),
});

// After
entity("users", {
  username: text().unique(),
});

// Check for duplicates via raw SQL or manual inspection
// Resolve duplicates by updating or deleting
// Then add .unique() constraint

// Before
entity("users", {
  email: text().required().unique(),
});

// After - loosening constraints is safe
entity("users", {
  email: text(),  // Now optional, non-unique
});

# See what sync would do without applying
npx bknd sync

# Applies only additive changes
npx bknd sync

# WARNING: This will drop tables/columns
npx bknd sync --force

# Specifically enables drop operations
npx bknd sync --drop

// scripts/migrate-schema.ts
import { App } from "bknd";

async function migrate() {
  const app = new App({
    connection: { url: process.env.DB_URL! },
  });
  await app.build();

  const api = app.getApi();

  console.log("Starting migration...");

  // Read all records from old structure
  const records = await api.data.readMany("old_entity", { limit: 100000 });
  console.log(`Found ${records.data.length} records`);

  // Transform and insert into new structure
  let migrated = 0;
  for (const record of records.data) {
    await api.data.createOne("new_entity", {
      // Transform fields as needed
      new_field: record.old_field,
    });
    migrated++;
    if (migrated % 100 === 0) {
      console.log(`Migrated ${migrated}/${records.data.length}`);
    }
  }

  console.log("Migration complete!");
  process.exit(0);
}

migrate().catch(console.error);

npx bun scripts/migrate-schema.ts
# or
npx ts-node scripts/migrate-schema.ts

# 1. Check sync status
npx bknd sync

# 2. Verify schema in debug output
npx bknd schema --pretty

const api = app.getApi();

// Verify field exists by querying
const result = await api.data.readMany("entity_name", { limit: 1 });
console.log(result.data[0]);  // Check field names/values