db-seed

) { console . log ( 'Seeding database...' ) ; // Clear existing data (reverse dependency order) await db . delete ( schema . comments ) ; await db . delete ( schema . posts ) ; await db . delete ( schema . users ) ; // Insert users const users = [ { id : crypto . randomUUID ( ) , name : 'Sarah Chen' , email : 'sarah@example.com' , ... } , // ... ] ; // D1 batch limit: 10 rows per INSERT for ( let i = 0 ; i < users . length ; i += 10 ) { await db . insert ( schema . users ) . values ( users . slice ( i , i + 10 ) ) ; } // Insert posts (references users) const posts = [ { id : crypto . randomUUID ( ) , userId : users [ 0 ] . id , title : '...' , ... } , // ... ] ; for ( let i = 0 ; i < posts . length ; i += 10 ) { await db . insert ( schema . posts ) . values ( posts . slice ( i , i + 10 ) ) ; } console . log ( Seeded: ${ users . length } users, ${ posts . length } posts ) ; } Run with: npx tsx scripts/seed.ts For Cloudflare Workers, add a seed endpoint (remove before production): app . post ( '/api/seed' , async ( c ) => { const db = drizzle ( c . env . DB ) ; await seed ( db ) ; return c . json ( { ok : true } ) ; } ) ; Raw SQL (D1) -- seed.sql -- Run: npx wrangler d1 execute DB_NAME --local --file=./scripts/seed.sql -- Clear existing (reverse order) DELETE FROM comments ; DELETE FROM posts ; DELETE FROM users ; -- Users INSERT INTO users ( id , name , email , created_at ) VALUES ( 'uuid-1' , 'Sarah Chen' , 'sarah@example.com' , '2025-01-15T10:30:00Z' ) , ( 'uuid-2' , 'James Wilson' , 'james@example.com' , '2025-02-01T14:22:00Z' ) ; -- Posts (max 10 rows per INSERT for D1) INSERT INTO posts ( id , user_id , title , body , created_at ) VALUES ( 'post-1' , 'uuid-1' , 'Getting Started' , 'Welcome to...' , '2025-03-01T09:00:00Z' ) ; 6. Idempotency Seed scripts must be safe to re-run: // Option A: Delete-then-insert (simple, loses data) await db . delete ( schema . users ) ; await db . insert ( schema . users ) . values ( seedUsers ) ; // Option B: Upsert (preserves non-seed data) for ( const user of seedUsers ) { await db . insert ( schema . users ) . values ( user ) . onConflictDoUpdate ( { target : schema . users . id , set : user } ) ; } Default to Option A for dev/testing, Option B for demo (where users may have added their own data). D1-Specific Gotchas Gotcha Solution Max ~10 rows per INSERT Batch inserts in chunks of 10 No native BOOLEAN Use INTEGER (0/1) No native DATETIME Use TEXT with ISO 8601 strings JSON stored as TEXT JSON.stringify() before insert Foreign keys always enforced Insert parent tables first 100 bound parameter limit Keep batch size × columns < 100 Quality Rules Match the domain — an e-commerce seed has products with real-sounding names and prices, not "Product 1" Vary the data — don't make every user "John Smith" or every price "$9.99" Include edge cases (for testing seeds) — empty strings, very long text, special characters, maximum values Reference real IDs — foreign keys must point to actually-inserted parent rows Print what was seeded — always log counts so the user knows it worked Document the run command — put it in a comment at the top of the file