Generate copyWith method for data classes

README.md

@@ -253,6 +253,35 @@ We can now change the `database` class like this:
 ```
 You can also add individual tables or drop them.
 
+### Extracting functionality with DAOs
+When you have a lot of queries, putting them all into one class quickly becomes
+tedious. You can avoid this by extracting some queries into classes that are 
+available from your main database class. Consider the following code:
+```dart
+part 'todos_dao.g.dart';
+
+// the _TodosDaoMixin will be created by sally. It contains all the necessary
+// fields for the tables. The <MyDatabase> type annotation is the database class
+// that should use this dao.
+@UseDao(tables: [Todos])
+class TodosDao extends DatabaseAccessor<MyDatabase> with _TodosDaoMixin {
+  // this constructor is required so that the main database can create an instance
+  // of this object.
+  TodosDao(Database db) : super(db);
+
+  Stream<List<TodoEntry>> todosInCategory(Category category) {
+    if (category == null) {
+      return (select(todos)..where((t) => isNull(t.category))).watch();
+    } else {
+      return (select(todos)..where((t) => t.category.equals(category.id)))
+          .watch();
+    }
+  }
+}
+```
+If we now change the annotation on the `MyDatabase` class to `@UseSally(tables: [Todos, Categories], daos: [TodosDao])`
+and re-run the code generation, a getter `todosDao` can be used to access the instance of that dao.
+
 ## TODO-List and current limitations
 ### Limitations (at the moment)
 Please note that a workaround for most on this list exists with custom statements.
@@ -266,11 +295,8 @@ These aren't sorted by priority. If you have more ideas or want some features ha
 let us know by creating an issue!
 - Specify primary keys
   - Support an simplified update that doesn't need an explicit where based on the primary key
-- Data classes: Generate a `copyWith` method.
 - Simple `COUNT(*)` operations (group operations will be much more complicated)
 - Support default values and expressions
-- Allow using DAOs or some other mechanism instead of having to put everything in the main 
-database class.
 - Support more Datatypes: We should at least support `Uint8List` out of the box,
 supporting floating / fixed point numbers as well would be awesome
 - Nullable / non-nullable datatypes

sally_flutter/README.md

@@ -253,6 +253,35 @@ We can now change the `database` class like this:
 ```
 You can also add individual tables or drop them.
 
+### Extracting functionality with DAOs
+When you have a lot of queries, putting them all into one class quickly becomes
+tedious. You can avoid this by extracting some queries into classes that are 
+available from your main database class. Consider the following code:
+```dart
+part 'todos_dao.g.dart';
+
+// the _TodosDaoMixin will be created by sally. It contains all the necessary
+// fields for the tables. The <MyDatabase> type annotation is the database class
+// that should use this dao.
+@UseDao(tables: [Todos])
+class TodosDao extends DatabaseAccessor<MyDatabase> with _TodosDaoMixin {
+  // this constructor is required so that the main database can create an instance
+  // of this object.
+  TodosDao(Database db) : super(db);
+
+  Stream<List<TodoEntry>> todosInCategory(Category category) {
+    if (category == null) {
+      return (select(todos)..where((t) => isNull(t.category))).watch();
+    } else {
+      return (select(todos)..where((t) => t.category.equals(category.id)))
+          .watch();
+    }
+  }
+}
+```
+If we now change the annotation on the `MyDatabase` class to `@UseSally(tables: [Todos, Categories], daos: [TodosDao])`
+and re-run the code generation, a getter `todosDao` can be used to access the instance of that dao.
+
 ## TODO-List and current limitations
 ### Limitations (at the moment)
 Please note that a workaround for most on this list exists with custom statements.
@@ -266,11 +295,8 @@ These aren't sorted by priority. If you have more ideas or want some features ha
 let us know by creating an issue!
 - Specify primary keys
   - Support an simplified update that doesn't need an explicit where based on the primary key
-- Data classes: Generate a `copyWith` method.
 - Simple `COUNT(*)` operations (group operations will be much more complicated)
 - Support default values and expressions
-- Allow using DAOs or some other mechanism instead of having to put everything in the main 
-database class.
 - Support more Datatypes: We should at least support `Uint8List` out of the box,
 supporting floating / fixed point numbers as well would be awesome
 - Nullable / non-nullable datatypes

sally_flutter/example/README.md

@@ -1,3 +0,0 @@
-# sally_example
-
-This is a simple todo list app that uses sally as a persistence library.

sally_flutter/example/lib/database/database.g.dart

@@ -23,6 +23,14 @@ class TodoEntry {
       category: intType.mapFromDatabaseResponse(data['category']),
     );
   }
+  TodoEntry copyWith(
+          {int id, String content, DateTime targetDate, int category}) =>
+      TodoEntry(
+        id: id ?? this.id,
+        content: content ?? this.content,
+        targetDate: targetDate ?? this.targetDate,
+        category: category ?? this.category,
+      );
   @override
   int get hashCode =>
       (((id.hashCode) * 31 + content.hashCode) * 31 + targetDate.hashCode) *
@@ -109,6 +117,10 @@ class Category {
       description: stringType.mapFromDatabaseResponse(data['`desc`']),
     );
   }
+  Category copyWith({int id, String description}) => Category(
+        id: id ?? this.id,
+        description: description ?? this.description,
+      );
   @override
   int get hashCode => (id.hashCode) * 31 + description.hashCode;
   @override

sally_generator/lib/src/writer/data_class_writer.dart

@@ -26,6 +26,9 @@ class DataClassWriter {
     // Also write parsing factory
     _writeMappingConstructor(buffer);
 
+    // And a convenience method to copy data from this class.
+    _writeCopyWith(buffer);
+
     buffer.write('@override\n int get hashCode => ');
 
     if (table.columns.isEmpty) {
@@ -36,7 +39,7 @@ class DataClassWriter {
     }
 
     // override ==
-    //    return identical(this, other) || (other is DataClass && other.id == id && other.)
+    //    return identical(this, other) || (other is DataClass && other.id == id && ...)
     buffer
       ..write('@override\nbool operator ==(other) => ')
       ..write('identical(this, other) || (other is ${table.dartTypeName}');
@@ -89,6 +92,32 @@ class DataClassWriter {
     buffer.write(');}\n');
   }
 
+  void _writeCopyWith(StringBuffer buffer) {
+    final dataClassName = table.dartTypeName;
+
+    buffer.write('$dataClassName copyWith({');
+    for (var i = 0; i < table.columns.length; i++) {
+      final column = table.columns[i];
+      final last = i == table.columns.length - 1;
+
+      buffer.write('${column.dartTypeName} ${column.dartGetterName}');
+      if (!last) {
+        buffer.write(',');
+      }
+    }
+
+    buffer.write('}) => $dataClassName(');
+
+    for (var column in table.columns) {
+      // we also have a method parameter called getter, so we can use
+      // field: field ?? this.field
+      final getter = column.dartGetterName;
+      buffer.write('$getter: $getter ?? this.$getter,');
+    }
+
+    buffer.write(');');
+  }
+
   /// Recursively creates the implementation for hashCode of the data class,
   /// assuming it has at least one field. When it has one field, we just return
   /// the hash code of that field. Otherwise, we multiply it with 31 and add