Implement replace API as a companion for updates

sally/example/example.g.dart

@@ -53,19 +53,19 @@ class $CategoriesTable extends Categories
       id.isAcceptableValue(instance.id, isInserting) &&
       description.isAcceptableValue(instance.description, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => null;
+  Set<GeneratedColumn> get $primaryKey => {id};
   @override
   Category map(Map<String, dynamic> data) {
     return Category.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(Category d) {
+  Map<String, Variable> entityToSql(Category d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.description != null) {
+    if (d.description != null || includeNulls) {
       map['description'] = Variable<String, StringType>(d.description);
     }
     return map;
@@ -142,25 +142,25 @@ class $RecipesTable extends Recipes implements TableInfo<Recipes, Recipe> {
       instructions.isAcceptableValue(instance.instructions, isInserting) &&
       category.isAcceptableValue(instance.category, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => null;
+  Set<GeneratedColumn> get $primaryKey => {id};
   @override
   Recipe map(Map<String, dynamic> data) {
     return Recipe.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(Recipe d) {
+  Map<String, Variable> entityToSql(Recipe d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.title != null) {
+    if (d.title != null || includeNulls) {
       map['title'] = Variable<String, StringType>(d.title);
     }
-    if (d.instructions != null) {
+    if (d.instructions != null || includeNulls) {
       map['instructions'] = Variable<String, StringType>(d.instructions);
     }
-    if (d.category != null) {
+    if (d.category != null || includeNulls) {
       map['category'] = Variable<int, IntType>(d.category);
     }
     return map;
@@ -227,22 +227,22 @@ class $IngredientsTable extends Ingredients
       name.isAcceptableValue(instance.name, isInserting) &&
       caloriesPer100g.isAcceptableValue(instance.caloriesPer100g, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => null;
+  Set<GeneratedColumn> get $primaryKey => {id};
   @override
   Ingredient map(Map<String, dynamic> data) {
     return Ingredient.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(Ingredient d) {
+  Map<String, Variable> entityToSql(Ingredient d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.name != null) {
+    if (d.name != null || includeNulls) {
       map['name'] = Variable<String, StringType>(d.name);
     }
-    if (d.caloriesPer100g != null) {
+    if (d.caloriesPer100g != null || includeNulls) {
       map['calories'] = Variable<int, IntType>(d.caloriesPer100g);
     }
     return map;
@@ -321,15 +321,16 @@ class $IngredientInRecipesTable extends IngredientInRecipes
   }
 
   @override
-  Map<String, Variable> entityToSql(IngredientInRecipe d) {
+  Map<String, Variable> entityToSql(IngredientInRecipe d,
+      {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.recipe != null) {
+    if (d.recipe != null || includeNulls) {
       map['recipe'] = Variable<int, IntType>(d.recipe);
     }
-    if (d.ingredient != null) {
+    if (d.ingredient != null || includeNulls) {
       map['ingredient'] = Variable<int, IntType>(d.ingredient);
     }
-    if (d.amountInGrams != null) {
+    if (d.amountInGrams != null || includeNulls) {
       map['amount'] = Variable<int, IntType>(d.amountInGrams);
     }
     return map;

sally/lib/src/runtime/exceptions.dart

@@ -3,4 +3,11 @@ class InvalidDataException implements Exception {
   final String message;
 
   InvalidDataException(this.message);
+
+  @override
+  String toString() {
+    return 'InvalidDataException: $message';
+  }
+
+
 }

sally/lib/src/runtime/expressions/custom.dart

@@ -0,0 +1,16 @@
+import 'package:sally/sally.dart';
+import 'package:sally/src/runtime/components/component.dart';
+import 'package:sally/src/runtime/expressions/expression.dart';
+
+class CustomExpression<D, S extends SqlType<D>> extends Expression<D, S> {
+
+  final String content;
+
+  CustomExpression(this.content);
+
+  @override
+  void writeInto(GenerationContext context) {
+    context.buffer.write(content);
+  }
+
+}

sally/lib/src/runtime/expressions/variables.dart

@@ -39,8 +39,12 @@ class Variable<T, S extends SqlType<T>> extends Expression<T, S> {
 
   @override
   void writeInto(GenerationContext context) {
-    context.buffer.write('?');
-    context.introduceVariable(mapToSimpleValue(context));
+    if (value != null) {
+      context.buffer.write('?');
+      context.introduceVariable(mapToSimpleValue(context));
+    } else {
+      context.buffer.write('NULL');
+    }
   }
 }
 

sally/lib/src/runtime/migration.dart

@@ -55,21 +55,23 @@ class Migrator {
   Future<void> createTable(TableInfo table) async {
     final sql = StringBuffer();
 
-    // todo write primary key
-
     // ignore: cascade_invocations
     sql.write('CREATE TABLE IF NOT EXISTS ${table.$tableName} (');
 
+    var hasAutoIncrement = false;
     for (var i = 0; i < table.$columns.length; i++) {
       final column = table.$columns[i];
 
+      if (column is GeneratedIntColumn && column.hasAutoIncrement)
+        hasAutoIncrement = true;
+
       // ignore: cascade_invocations
       column.writeColumnDefinition(sql);
 
       if (i < table.$columns.length - 1) sql.write(', ');
     }
 
-    if (table.$primaryKey != null) {
+    if (table.$primaryKey != null && !hasAutoIncrement) {
       sql.write(', PRIMARY KEY (');
       final pkList = table.$primaryKey.toList(growable: false);
       for (var i = 0; i < pkList.length; i++) {

sally/lib/src/runtime/statements/update.dart

@@ -2,12 +2,15 @@ import 'dart:async';
 
 import 'package:sally/sally.dart';
 import 'package:sally/src/runtime/components/component.dart';
+import 'package:sally/src/runtime/components/where.dart';
+import 'package:sally/src/runtime/expressions/custom.dart';
+import 'package:sally/src/runtime/expressions/expression.dart';
 
 class UpdateStatement<T, D> extends Query<T, D> {
   UpdateStatement(QueryEngine database, TableInfo<T, D> table)
       : super(database, table);
 
-  Map<String, dynamic> _updatedFields;
+  Map<String, Variable> _updatedFields;
 
   @override
   void writeStartPart(GenerationContext ctx) {
@@ -29,10 +32,31 @@ class UpdateStatement<T, D> extends Query<T, D> {
     });
   }
 
+  Future<int> _performQuery() async {
+    final ctx = constructQuery();
+    final rows = await ctx.database.executor.doWhenOpened((e) async {
+      return await e.runUpdate(ctx.sql, ctx.boundVariables);
+    });
+
+    if (rows > 0) {
+      database.markTableUpdated(table.$tableName);
+    }
+
+    return rows;
+  }
+
   /// Writes all non-null fields from [entity] into the columns of all rows
   /// that match the set [where] and limit constraints. Warning: That also
   /// means that, when you're not setting a where or limit expression
   /// explicitly, this method will update all rows in the specific table.
+  ///
+  /// The fields that are null on the [entity] object will not be changed by
+  /// this operation.
+  ///
+  /// Returns the amount of rows that have been affected by this operation.
+  ///
+  /// See also: [replace], which does not require [where] statements and
+  /// supports setting fields to null.
   Future<int> write(D entity) async {
     if (!table.validateIntegrity(entity, false)) {
       throw InvalidDataException(
@@ -47,15 +71,59 @@ class UpdateStatement<T, D> extends Query<T, D> {
       return Future.value(0);
     }
 
-    final ctx = constructQuery();
-    final rows = await ctx.database.executor.doWhenOpened((e) async {
-      return await e.runUpdate(ctx.sql, ctx.boundVariables);
-    });
+    return await _performQuery();
+  }
 
-    if (rows > 0) {
-      database.markTableUpdated(table.$tableName);
+  /// Replaces the old version of [entity] that is stored in the database with
+  /// the fields of the [entity] provided here. This implicitly applies a
+  /// [where] clause to rows with the same primary key as [entity], so that only
+  /// the row representing outdated data will be replaced.
+  ///
+  /// If [entity] has fields with null as value, data in the row will be set
+  /// back to null. This behavior is different to that of [write], which ignores
+  /// null fields.
+  ///
+  /// Returns true if a row was affected by this operation.
+  Future<bool> replace(D entity) async {
+    // We set isInserting to true here although we're in an update. This is
+    // because all the fields from the entity will be written (as opposed to a
+    // regular update, where only non-null fields will be written). If isInserted
+    // was false, the null fields would not be validated.
+    if (!table.validateIntegrity(entity, true))
+      throw InvalidDataException('Invalid data: $entity cannot be used to '
+          'replace another row as some required fields are null or invalid.');
+
+    assert(
+        whereExpr == null,
+        'When using replace on an update statement, you may not use where(...)'
+        'as well. The where clause will be determined automatically');
+
+    _updatedFields = table.entityToSql(entity, includeNulls: true);
+    final primaryKeys = table.$primaryKey.map((c) => c.$name);
+
+    // Extract values of the primary key as they are needed for the where clause
+    final primaryKeyValues = Map.fromEntries(_updatedFields.entries
+        .where((entry) => primaryKeys.contains(entry.key)));
+
+    // But remove them from the map of columns that should be changed.
+    _updatedFields.removeWhere((key, _) => primaryKeys.contains(key));
+
+    Expression<bool, BoolType> predicate;
+    for (var entry in primaryKeyValues.entries) {
+      // custom expression that references the column
+      final columnExpression = CustomExpression(entry.key);
+      final comparison = Comparison(columnExpression, ComparisonOperator.equal, entry.value);
+
+      if (predicate == null) {
+        predicate = comparison;
+      } else {
+        predicate = and(predicate, comparison);
+      }
     }
 
-    return rows;
+    whereExpr = Where(predicate);
+
+    final updatedRows = await _performQuery();
+    return updatedRows != 0;
   }
 }

sally/lib/src/runtime/structure/table_info.dart

@@ -23,10 +23,14 @@ abstract class TableInfo<TableDsl, DataClass> {
   /// auto-incrementing are allowed to be null as they will be set by sqlite.
   bool validateIntegrity(DataClass instance, bool isInserting);
 
-  /// Maps the given data class into a map that can be inserted into sql. The
+  /// Maps the given data class to a [Map] that can be inserted into sql. The
   /// keys should represent the column name in sql, the values the corresponding
   /// values of the field.
-  Map<String, Variable> entityToSql(DataClass instance);
+  ///
+  /// If [includeNulls] is true, fields of the [DataClass] that are null will be
+  /// written as a [Variable] with a value of null. Otherwise, these fields will
+  /// not be written into the map at all.
+  Map<String, Variable> entityToSql(DataClass instance, {bool includeNulls = false});
 
   /// Maps the given row returned by the database into the fitting data class.
   DataClass map(Map<String, dynamic> data);

sally/test/data/tables/todos.g.dart

@@ -96,28 +96,28 @@ class $TodosTableTable extends TodosTable
       targetDate.isAcceptableValue(instance.targetDate, isInserting) &&
       category.isAcceptableValue(instance.category, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => null;
+  Set<GeneratedColumn> get $primaryKey => {id};
   @override
   TodoEntry map(Map<String, dynamic> data) {
     return TodoEntry.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(TodoEntry d) {
+  Map<String, Variable> entityToSql(TodoEntry d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.title != null) {
+    if (d.title != null || includeNulls) {
       map['title'] = Variable<String, StringType>(d.title);
     }
-    if (d.content != null) {
+    if (d.content != null || includeNulls) {
       map['content'] = Variable<String, StringType>(d.content);
     }
-    if (d.targetDate != null) {
+    if (d.targetDate != null || includeNulls) {
       map['target_date'] = Variable<DateTime, DateTimeType>(d.targetDate);
     }
-    if (d.category != null) {
+    if (d.category != null || includeNulls) {
       map['category'] = Variable<int, IntType>(d.category);
     }
     return map;
@@ -171,19 +171,19 @@ class $CategoriesTable extends Categories
       id.isAcceptableValue(instance.id, isInserting) &&
       description.isAcceptableValue(instance.description, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => null;
+  Set<GeneratedColumn> get $primaryKey => {id};
   @override
   Category map(Map<String, dynamic> data) {
     return Category.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(Category d) {
+  Map<String, Variable> entityToSql(Category d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.description != null) {
+    if (d.description != null || includeNulls) {
       map['`desc`'] = Variable<String, StringType>(d.description);
     }
     return map;
@@ -248,22 +248,22 @@ class $UsersTable extends Users implements TableInfo<Users, User> {
       name.isAcceptableValue(instance.name, isInserting) &&
       isAwesome.isAcceptableValue(instance.isAwesome, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => null;
+  Set<GeneratedColumn> get $primaryKey => {id};
   @override
   User map(Map<String, dynamic> data) {
     return User.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(User d) {
+  Map<String, Variable> entityToSql(User d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.name != null) {
+    if (d.name != null || includeNulls) {
       map['name'] = Variable<String, StringType>(d.name);
     }
-    if (d.isAwesome != null) {
+    if (d.isAwesome != null || includeNulls) {
       map['is_awesome'] = Variable<bool, BoolType>(d.isAwesome);
     }
     return map;
@@ -325,12 +325,12 @@ class $SharedTodosTable extends SharedTodos
   }
 
   @override
-  Map<String, Variable> entityToSql(SharedTodo d) {
+  Map<String, Variable> entityToSql(SharedTodo d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.todo != null) {
+    if (d.todo != null || includeNulls) {
       map['todo'] = Variable<int, IntType>(d.todo);
     }
-    if (d.user != null) {
+    if (d.user != null || includeNulls) {
       map['user'] = Variable<int, IntType>(d.user);
     }
     return map;

sally/test/expressions/variable_test.dart

@@ -15,4 +15,14 @@ void main() {
     expect('?', ctx.sql);
     expect(ctx.boundVariables, [1551297563]);
   });
+
+  test('writes null directly for null values', () {
+    final variable = Variable.withString(null);
+    final ctx = GenerationContext(TodoDb(null));
+
+    variable.writeInto(ctx);
+
+    expect('NULL', ctx.sql);
+    expect(ctx.boundVariables, isEmpty);
+  });
 }

sally/test/update_test.dart

@@ -37,6 +37,20 @@ void main() {
     });
   });
 
+  test('generates replace statements', () async {
+    await db.update(db.todosTable).replace(TodoEntry(
+          id: 3,
+          title: 'Title',
+          content: 'Updated content',
+          // category and targetDate are null
+        ));
+
+    verify(executor.runUpdate(
+        'UPDATE todos SET title = ?, content = ?, '
+        'target_date = NULL, category = NULL WHERE id = ?;',
+        ['Title', 'Updated content', 3]));
+  });
+
   test('does not update with invalid data', () {
     // The length of a title must be between 4 and 16 chars
 
@@ -45,7 +59,7 @@ void main() {
     }, throwsA(const TypeMatcher<InvalidDataException>()));
   });
 
-  group('Table updates for delete statements', () {
+  group('Table updates for update statements', () {
     test('are issued when data was changed', () async {
       when(executor.runUpdate(any, any)).thenAnswer((_) => Future.value(3));
 

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

@@ -80,25 +80,25 @@ class $TodosTable extends Todos implements TableInfo<Todos, TodoEntry> {
       targetDate.isAcceptableValue(instance.targetDate, isInserting) &&
       category.isAcceptableValue(instance.category, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => <GeneratedColumn>{};
+  Set<GeneratedColumn> get $primaryKey => null;
   @override
   TodoEntry map(Map<String, dynamic> data) {
     return TodoEntry.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(TodoEntry d) {
+  Map<String, Variable> entityToSql(TodoEntry d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.content != null) {
+    if (d.content != null || includeNulls) {
       map['content'] = Variable<String, StringType>(d.content);
     }
-    if (d.targetDate != null) {
+    if (d.targetDate != null || includeNulls) {
       map['target_date'] = Variable<DateTime, DateTimeType>(d.targetDate);
     }
-    if (d.category != null) {
+    if (d.category != null || includeNulls) {
       map['category'] = Variable<int, IntType>(d.category);
     }
     return map;
@@ -152,19 +152,19 @@ class $CategoriesTable extends Categories
       id.isAcceptableValue(instance.id, isInserting) &&
       description.isAcceptableValue(instance.description, isInserting);
   @override
-  Set<GeneratedColumn> get $primaryKey => <GeneratedColumn>{};
+  Set<GeneratedColumn> get $primaryKey => null;
   @override
   Category map(Map<String, dynamic> data) {
     return Category.fromData(data, _db);
   }
 
   @override
-  Map<String, Variable> entityToSql(Category d) {
+  Map<String, Variable> entityToSql(Category d, {bool includeNulls = false}) {
     final map = <String, Variable>{};
-    if (d.id != null) {
+    if (d.id != null || includeNulls) {
       map['id'] = Variable<int, IntType>(d.id);
     }
-    if (d.description != null) {
+    if (d.description != null || includeNulls) {
       map['`desc`'] = Variable<String, StringType>(d.description);
     }
     return map;

sally_generator/lib/src/writer/table_writer.dart

@@ -63,15 +63,16 @@ class TableWriter {
   }
 
   void _writeReverseMappingMethod(StringBuffer buffer) {
-    // Map<String, Variable> entityToSql(User d) {
+    // Map<String, Variable> entityToSql(User d, {bool includeNulls = false) {
     buffer
       ..write(
-          '@override\nMap<String, Variable> entityToSql(${table.dartTypeName} d) {\n')
+          '@override\nMap<String, Variable> entityToSql('
+              '${table.dartTypeName} d, {bool includeNulls = false}) {\n')
       ..write('final map = <String, Variable> {};');
 
     for (var column in table.columns) {
       buffer.write('''
-        if (d.${column.dartGetterName} != null) {
+        if (d.${column.dartGetterName} != null || includeNulls) {
           map['${column.name.name}'] = Variable<${column.dartTypeName}, ${column.sqlTypeName}>(d.${column.dartGetterName});
         }
       ''');
@@ -138,13 +139,20 @@ class TableWriter {
 
   void _writePrimaryKeyOverride(StringBuffer buffer) {
     buffer.write('@override\nSet<GeneratedColumn> get \$primaryKey => ');
-    if (table.primaryKey == null) {
+    var primaryKey = table.primaryKey;
+
+    // If there is an auto increment column, that forms the primary key. The
+    // PK returned by table.primaryKey only contains column that have been
+    // explicitly defined as PK, but with AI this happens implicitly.
+    primaryKey ??= table.columns.where((c) => c.hasAI).toSet();
+
+    if (primaryKey == null) {
       buffer.write('null;');
       return;
     }
 
     buffer.write('{');
-    final pkList = table.primaryKey.toList();
+    final pkList = primaryKey.toList();
     for (var i = 0; i < pkList.length; i++) {
       final pk = pkList[i];