From 6f8757829e331e77143bed8879b6432bdf16358f Mon Sep 17 00:00:00 2001
From: Simon Binder <oss@simonbinder.eu>
Date: Sun, 20 Oct 2019 14:21:31 +0200
Subject: [PATCH] Schema entities as abstraction layer, model for triggers

---
 moor/lib/moor.dart                            |  1 +
 moor/lib/src/runtime/database.dart            |  4 +++
 moor/lib/src/runtime/structure/entities.dart  | 27 +++++++++++++++++++
 .../lib/src/runtime/structure/table_info.dart |  7 ++++-
 4 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 moor/lib/src/runtime/structure/entities.dart

diff --git a/moor/lib/moor.dart b/moor/lib/moor.dart
index 38440205..3f99db78 100644
--- a/moor/lib/moor.dart
+++ b/moor/lib/moor.dart
@@ -26,6 +26,7 @@ export 'package:moor/src/runtime/statements/update.dart';
 export 'package:moor/src/runtime/statements/insert.dart';
 export 'package:moor/src/runtime/statements/delete.dart';
 export 'package:moor/src/runtime/structure/columns.dart';
+export 'package:moor/src/runtime/structure/entities.dart';
 export 'package:moor/src/runtime/structure/error_handling.dart';
 export 'package:moor/src/runtime/structure/table_info.dart';
 export 'package:moor/src/runtime/data_class.dart';
diff --git a/moor/lib/src/runtime/database.dart b/moor/lib/src/runtime/database.dart
index 832ee2b5..6c53990d 100644
--- a/moor/lib/src/runtime/database.dart
+++ b/moor/lib/src/runtime/database.dart
@@ -371,6 +371,10 @@ abstract class GeneratedDatabase extends DatabaseConnectionUser
   /// A list of tables specified in this database.
   List<TableInfo> get allTables;
 
+  /// All entities (tables, views, triggers, indexes) that are declared in this
+  /// database.
+  List<DatabaseSchemaEntity> get allEntities => allTables;
+
   /// Used by generated code
   GeneratedDatabase(SqlTypeSystem types, QueryExecutor executor,
       {StreamQueryStore streamStore})
diff --git a/moor/lib/src/runtime/structure/entities.dart b/moor/lib/src/runtime/structure/entities.dart
new file mode 100644
index 00000000..5d5cdebb
--- /dev/null
+++ b/moor/lib/src/runtime/structure/entities.dart
@@ -0,0 +1,27 @@
+/// Some abstract schema entity that can be stored in a database. This includes
+/// tables, triggers, views, indexes, etc.
+abstract class DatabaseSchemaEntity {
+  /// The (unalised) name of this entity in the database.
+  String get entityName;
+}
+
+/// A sqlite trigger that's executed before, after or instead of a subset of
+/// writes on a specific tables.
+/// In moor, triggers can only be declared in `.moor` files.
+///
+/// For more information on triggers, see the [CREATE TRIGGER][sqlite-docs]
+/// documentation from sqlite, or the [entry on sqlitetutorial.net][sql-tutorial].
+///
+/// [sqlite-docs]: (https://sqlite.org/lang_createtrigger.html)
+/// [sql-tutorial]: (https://www.sqlitetutorial.net/sqlite-trigger/)
+class Trigger extends DatabaseSchemaEntity {
+  /// The `CREATE TRIGGER` sql statement that can be used to create this
+  /// trigger.
+  final String createTriggerStmt;
+  @override
+  final String entityName;
+
+  /// Creates a trigger representation by the [createTriggerStmt] and its
+  /// [entityName]. Mainly used by generated code.
+  Trigger(this.createTriggerStmt, this.entityName);
+}
diff --git a/moor/lib/src/runtime/structure/table_info.dart b/moor/lib/src/runtime/structure/table_info.dart
index 468b3675..77b21d9c 100644
--- a/moor/lib/src/runtime/structure/table_info.dart
+++ b/moor/lib/src/runtime/structure/table_info.dart
@@ -4,7 +4,8 @@ import 'package:moor/src/runtime/expressions/variables.dart';
 /// Base class for generated classes. [TableDsl] is the type specified by the
 /// user that extends [Table], [D] is the type of the data class
 /// generated from the table.
-mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table {
+mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table
+    implements DatabaseSchemaEntity {
   /// Type system sugar. Implementations are likely to inherit from both
   /// [TableInfo] and [TableDsl] and can thus just return their instance.
   TableDsl get asDslTable;
@@ -29,6 +30,9 @@ mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table {
   /// be aliased.
   String get actualTableName;
 
+  @override
+  String get entityName => actualTableName;
+
   /// The table name, optionally suffixed with the alias if one exists. This
   /// can be used in select statements, as it returns something like "users u"
   /// for a table called users that has been aliased as "u".
@@ -40,6 +44,7 @@ mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table {
     }
   }
 
+  /// All columns defined in this table.
   List<GeneratedColumn> get $columns;
 
   /// Validates that the given entity can be inserted into this table, meaning