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Remove non-existent withSystemColumns parameter from documentation and fix code generator for LWW columns (#47)
* Initial plan * Remove non-existent withSystemColumns parameter from documentation Co-authored-by: graknol <[email protected]> * Fix generator to skip __hlc columns and add test Co-authored-by: graknol <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: graknol <[email protected]>
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declarative_sqlite_generator/lib/src/builder.dart

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@@ -130,6 +130,11 @@ class DeclarativeSqliteGenerator extends GeneratorForAnnotation<GenerateDbRecord
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continue;
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}
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// Skip HLC columns - they are internal implementation details for LWW sync
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if (col.name.endsWith('__hlc')) {
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continue;
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}
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final propertyName = _camelCase(col.name);
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final dartType = _getDartTypeForColumn(col.logicalType, col.isNotNull);
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final getterMethod =
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# Generator Tests
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This directory contains tests for the declarative_sqlite_generator package.
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## Running Tests
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```bash
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cd declarative_sqlite_generator
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dart test
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```
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## Testing the LWW HLC Column Fix
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The `lww_hlc_column_test.dart` file tests that the generator correctly skips `__hlc` columns when generating typed accessors.
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### Background
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When a column is marked with `.lww()` (Last-Write-Wins), the library automatically creates a companion `__hlc` column to store the Hybrid Logical Clock timestamp for conflict resolution. For example:
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```dart
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table.text('description').notNull('').lww();
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```
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This creates two columns:
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- `description` - the actual user data
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- `description__hlc` - the HLC timestamp (internal use only)
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### The Fix
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The generator now skips these `__hlc` columns when generating typed properties, because:
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1. They are internal implementation details for synchronization
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2. There are no `getHlc`/`setHlc` methods on `DbRecord` to access them
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3. Users should not directly manipulate these columns
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The fix is in `lib/src/builder.dart` around line 133:
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```dart
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// Skip HLC columns - they are internal implementation details for LWW sync
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if (col.name.endsWith('__hlc')) {
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continue;
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}
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```
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### Manual Testing with the Demo App
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You can also test this with the demo app:
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1. Update the demo schema to include LWW columns (already done in `demo/lib/schema.dart`)
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2. Run the code generator:
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```bash
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cd demo
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flutter pub get
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flutter pub run build_runner build --delete-conflicting-outputs
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```
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3. Check the generated `*.db.dart` files - they should NOT contain properties for `__hlc` columns
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4. The generated code should compile without errors
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### What Was Fixed
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Before the fix, if you had:
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```dart
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table.text('description').notNull('').lww();
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```
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The generator would create:
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```dart
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String get description => getTextNotNull('description');
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set description(String value) => setText('description', value);
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Hlc? get descriptionHlc => getHlc('description__hlc'); // ❌ ERROR: getHlc doesn't exist
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```
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After the fix:
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```dart
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String get description => getTextNotNull('description');
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set description(String value) => setText('description', value);
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// ✅ No descriptionHlc accessor generated
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```
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import 'package:test/test.dart';
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import 'package:declarative_sqlite/declarative_sqlite.dart';
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import 'package:declarative_sqlite_generator/src/builder.dart';
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void main() {
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group('LWW HLC Column Generation Tests', () {
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test('does not generate accessors for __hlc columns', () {
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// Create a schema with LWW columns
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final schemaBuilder = SchemaBuilder();
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schemaBuilder.table('tasks', (table) {
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table.guid('id').notNull('00000000-0000-0000-0000-000000000000');
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table.text('title').notNull('Default Title').lww(); // LWW column
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table.text('description').notNull('Default Description').lww(); // LWW column
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table.integer('priority').notNull(0); // Non-LWW column
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table.key(['id']).primary();
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});
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final schema = schemaBuilder.build();
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final table = schema.tables.firstWhere((t) => t.name == 'tasks');
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// Verify that __hlc columns were created for LWW columns
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final hlcColumns = table.columns.where((c) => c.name.endsWith('__hlc')).toList();
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expect(hlcColumns.length, equals(2),
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reason: 'Should have 2 __hlc columns for the 2 LWW columns');
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expect(hlcColumns.any((c) => c.name == 'title__hlc'), isTrue,
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reason: 'Should have title__hlc column');
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expect(hlcColumns.any((c) => c.name == 'description__hlc'), isTrue,
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reason: 'Should have description__hlc column');
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// Generate code using the generator
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final generator = DeclarativeSqliteGenerator(null as dynamic);
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// Use reflection or string inspection to verify __hlc columns are skipped
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// We'll check that the column list contains __hlc columns but they should be filtered
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final allColumns = table.columns.map((c) => c.name).toList();
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expect(allColumns, contains('title__hlc'));
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expect(allColumns, contains('description__hlc'));
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// The generator should skip these in _generateGettersAndSetters
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// This is verified by the code logic that checks col.name.endsWith('__hlc')
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print('Schema includes ${table.columns.length} columns total');
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print('User-visible columns (non-system, non-hlc): ${
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table.columns.where((c) =>
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!c.name.startsWith('system_') && !c.name.endsWith('__hlc')
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).length
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}');
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});
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test('skips system columns starting with system_', () {
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final schemaBuilder = SchemaBuilder();
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schemaBuilder.table('users', (table) {
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table.guid('id').notNull('00000000-0000-0000-0000-000000000000');
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table.text('name').notNull('Default Name');
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table.key(['id']).primary();
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});
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final schema = schemaBuilder.build();
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final table = schema.tables.firstWhere((t) => t.name == 'users');
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// Verify system columns were auto-created
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final systemColumns = table.columns.where((c) => c.name.startsWith('system_')).toList();
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expect(systemColumns.length, greaterThan(0),
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reason: 'System columns should be automatically added');
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// Verify we have the expected system columns
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expect(systemColumns.any((c) => c.name == 'system_id'), isTrue);
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expect(systemColumns.any((c) => c.name == 'system_created_at'), isTrue);
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expect(systemColumns.any((c) => c.name == 'system_version'), isTrue);
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expect(systemColumns.any((c) => c.name == 'system_is_local_origin'), isTrue);
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});
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test('counts correct number of user-visible columns with LWW', () {
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final schemaBuilder = SchemaBuilder();
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schemaBuilder.table('products', (table) {
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table.guid('id').notNull('00000000-0000-0000-0000-000000000000');
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table.text('name').notNull('').lww();
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table.real('price').notNull(0.0).lww();
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table.integer('stock').notNull(0); // Non-LWW
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table.key(['id']).primary();
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});
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final schema = schemaBuilder.build();
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final table = schema.tables.firstWhere((t) => t.name == 'products');
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// Count different types of columns
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final allColumns = table.columns;
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final systemColumns = allColumns.where((c) => c.name.startsWith('system_'));
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final hlcColumns = allColumns.where((c) => c.name.endsWith('__hlc'));
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final userColumns = allColumns.where((c) =>
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!c.name.startsWith('system_') && !c.name.endsWith('__hlc')
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);
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print('Total columns: ${allColumns.length}');
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print('System columns: ${systemColumns.length}');
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print('HLC columns: ${hlcColumns.length}');
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print('User columns: ${userColumns.length}');
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expect(userColumns.length, equals(4),
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reason: 'Should have 4 user-defined columns: id, name, price, stock');
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expect(hlcColumns.length, equals(2),
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reason: 'Should have 2 HLC columns for name and price');
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expect(systemColumns.length, equals(4),
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reason: 'Should have 4 system columns: system_id, system_created_at, system_version, system_is_local_origin');
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});
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});
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}

demo/lib/schema.dart

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// Users table
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builder.table('users', (table) {
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table.guid('id').notNull('');
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table.text('name').notNull('');
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table.text('email').notNull('');
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table.integer('age').notNull(0);
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table.text('gender').notNull('non-binary');
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table.integer('kids').notNull(0);
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table.text('name').notNull('').lww(); // LWW column for sync
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table.text('email').notNull('').lww(); // LWW column for sync
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table.integer('age').notNull(0).lww(); // LWW column for sync
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table.text('gender').notNull('non-binary').lww(); // LWW column for sync
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table.integer('kids').notNull(0).lww(); // LWW column for sync
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table.date('created_at').notNull().defaultCallback(() => DateTime.now());
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table.key(['id']).primary();
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});
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builder.table('posts', (table) {
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table.guid('id').notNull('');
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table.guid('user_id').notNull('');
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table.text('title').notNull('');
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table.text('content').notNull('');
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table.text('title').notNull('').lww(); // LWW column for sync
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table.text('content').notNull('').lww(); // LWW column for sync
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table.date('created_at').notNull().defaultCallback(() => DateTime.now());
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table.text('user_name').notNull(''); // Denormalized for demo simplicity
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table.key(['id']).primary();

docs/docs/core-library/data-synchronization.md

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When you use `declarative_sqlite`'s sync features, every row modification is stamped with an HLC value. This allows the server and client to determine which version of a row is newer, resolving conflicts using a "last-write-wins" strategy.
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## 2. Enabling Change Tracking
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## 2. Automatic Change Tracking
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To enable synchronization for a table, you must define it with `withSystemColumns: true` in your schema.
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All user tables in `declarative_sqlite` automatically include system columns for synchronization. These columns are added automatically when you define a table:
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```dart
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builder.table('tasks', (table) {
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// ... column definitions
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},
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// This is crucial for synchronization
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withSystemColumns: true);
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table.guid('id').notNull().primary();
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table.text('title').notNull();
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// ... other column definitions
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});
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```
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This adds several system columns to your table, including:
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The library automatically adds several system columns to your table, including:
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- `system_id`: A unique, client-generated ID for the row.
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- `system_version`: The HLC timestamp of the last modification.
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- `system_created_at`: The HLC timestamp of when the row was created.
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- `system_is_local_origin`: Tracks whether the row was created locally (1) or came from the server (0).
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With this enabled, every `insert`, `update`, and `delete` operation is automatically recorded in a special `_dirty_rows` table. This table acts as an outbox of pending changes to be sent to the server.
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With these system columns, every `insert`, `update`, and `delete` operation is automatically recorded in a special `__dirty_rows` table. This table acts as an outbox of pending changes to be sent to the server.
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## Column Update Restrictions
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## 3. Implementing Synchronization Logic
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With change tracking enabled, you can now implement your own synchronization logic. The core of this is the `_dirty_rows` table, which acts as an outbox of pending changes.
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With change tracking enabled, you can now implement your own synchronization logic. The core of this is the `__dirty_rows` table, which acts as an outbox of pending changes.
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You can get the list of dirty rows by calling `database.getDirtyRows()`.
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1. **Local Change**: A user modifies a task in the app.
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- `declarative_sqlite` performs the `UPDATE` on the `tasks` table.
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- It automatically stamps the row with a new HLC timestamp.
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- It records the operation (e.g., `UPDATE tasks WHERE id = '...'`) in the `_dirty_rows` table.
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- It records the operation (e.g., `UPDATE tasks WHERE id = '...'`) in the `__dirty_rows` table.
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2. **Trigger Sync**: You trigger the synchronization process, for example, by calling `MySyncService.performSync()` periodically or in response to network status changes.
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3. **Send Local Changes**: The service pulls the pending operations from `_dirty_rows`, fetches the full records, and sends them to your server.
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3. **Send Local Changes**: The service pulls the pending operations from `__dirty_rows`, fetches the full records, and sends them to your server.
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4. **Server Processing**: The server receives the records. For each row, it compares the HLC timestamp from the client with the HLC timestamp it has for that row. It accepts the change only if the client's timestamp is newer (last-write-wins).
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5. **Fetch Remote Changes**: The service calls your `onFetch` function, providing the last known server timestamps. Your API client fetches any changes from the server that have occurred since the last sync.
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6. **Apply Server Changes**: The fetched changes are applied to the local database using `database.bulkLoad()`. This method intelligently inserts or updates records based on the incoming data, again respecting HLC timestamps to prevent overwriting newer local changes with older server data.

docs/docs/core-library/streaming-queries.md

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## Caching and Performance
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To further improve performance, streaming queries use an internal cache. For queries on tables with system columns (`withSystemColumns: true`), the manager can perform optimizations:
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To further improve performance, streaming queries use an internal cache. For queries on user tables (which automatically include system columns), the manager can perform optimizations:
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1. **Initial Fetch**: The query is run, and the results are mapped to objects and stored in a cache, indexed by their `system_id`.
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2. **On Data Change**: Instead of re-running the entire query, the manager can often fetch only the rows that have changed (based on their `system_version`).

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