Add migration script to fix microchip UNIQUE constraint

server/db/migrate_microchip.js

@@ -0,0 +1,138 @@
+#!/usr/bin/env node
+
+/**
+ * Migration: Fix microchip UNIQUE constraint
+ * 
+ * Problem: The microchip field had a UNIQUE constraint which prevents multiple NULL values.
+ * Solution: Remove the constraint and create a partial unique index that only applies to non-NULL values.
+ * 
+ * This script can be run safely multiple times.
+ */
+
+const Database = require('better-sqlite3');
+const path = require('path');
+const fs = require('fs');
+
+function migrateMicrochip() {
+  const dbPath = process.env.DB_PATH || path.join(__dirname, '../../data/breedr.db');
+  
+  if (!fs.existsSync(dbPath)) {
+    console.log('No database found at', dbPath);
+    console.log('Skipping migration - database will be created with correct schema.');
+    return;
+  }
+
+  console.log('Migrating database:', dbPath);
+  const db = new Database(dbPath);
+  db.pragma('foreign_keys = OFF'); // Temporarily disable for migration
+
+  try {
+    console.log('Starting microchip field migration...');
+
+    // Check if the old unique constraint exists
+    const tableInfo = db.pragma('table_info(dogs)');
+    const microchipField = tableInfo.find(col => col.name === 'microchip');
+    
+    if (!microchipField) {
+      console.log('Microchip field not found. Skipping migration.');
+      return;
+    }
+
+    // SQLite doesn't support ALTER COLUMN, so we need to recreate the table
+    console.log('Step 1: Creating new dogs table with correct schema...');
+    
+    db.exec(`
+      -- Create new table with correct schema
+      CREATE TABLE IF NOT EXISTS dogs_new (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        name TEXT NOT NULL,
+        registration_number TEXT UNIQUE,
+        breed TEXT NOT NULL,
+        sex TEXT NOT NULL CHECK(sex IN ('male', 'female')),
+        birth_date DATE,
+        color TEXT,
+        microchip TEXT,
+        photo_urls TEXT,
+        notes TEXT,
+        is_active INTEGER DEFAULT 1,
+        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+      );
+    `);
+
+    console.log('Step 2: Copying data from old table...');
+    
+    // Copy all data from old table to new table
+    db.exec(`
+      INSERT INTO dogs_new 
+      SELECT * FROM dogs;
+    `);
+
+    console.log('Step 3: Dropping old table and renaming new table...');
+    
+    // Drop old table and rename new table
+    db.exec(`
+      DROP TABLE dogs;
+      ALTER TABLE dogs_new RENAME TO dogs;
+    `);
+
+    console.log('Step 4: Creating partial unique index for microchip...');
+    
+    // Create partial unique index (only applies to non-NULL values)
+    db.exec(`
+      CREATE UNIQUE INDEX IF NOT EXISTS idx_dogs_microchip 
+      ON dogs(microchip) 
+      WHERE microchip IS NOT NULL;
+    `);
+
+    console.log('Step 5: Recreating other indexes...');
+    
+    // Recreate other indexes
+    db.exec(`
+      CREATE INDEX IF NOT EXISTS idx_dogs_name ON dogs(name);
+      CREATE INDEX IF NOT EXISTS idx_dogs_registration ON dogs(registration_number);
+    `);
+
+    console.log('Step 6: Recreating triggers...');
+    
+    // Recreate the updated_at trigger
+    db.exec(`
+      DROP TRIGGER IF EXISTS update_dogs_timestamp;
+      CREATE TRIGGER update_dogs_timestamp 
+      AFTER UPDATE ON dogs
+      FOR EACH ROW
+      BEGIN
+        UPDATE dogs SET updated_at = CURRENT_TIMESTAMP WHERE id = NEW.id;
+      END;
+    `);
+
+    console.log('✓ Migration completed successfully!');
+    console.log('✓ Microchip field is now optional and can be left empty.');
+    console.log('✓ Multiple dogs can have no microchip (NULL value).');
+    console.log('✓ Unique constraint still prevents duplicate microchip numbers.');
+
+  } catch (error) {
+    console.error('Migration failed:', error.message);
+    console.error('\nYou may need to restore from backup or manually fix the database.');
+    throw error;
+  } finally {
+    db.pragma('foreign_keys = ON'); // Re-enable foreign keys
+    db.close();
+  }
+}
+
+if (require.main === module) {
+  console.log('='.repeat(60));
+  console.log('BREEDR Database Migration: Microchip Field Fix');
+  console.log('='.repeat(60));
+  console.log('');
+  
+  migrateMicrochip();
+  
+  console.log('');
+  console.log('='.repeat(60));
+  console.log('Migration Complete');
+  console.log('='.repeat(60));
+}
+
+module.exports = { migrateMicrochip };