Fix hashcodes, document joins

docs/docs/writing_queries/custom_queries.md

@@ -2,6 +2,7 @@
 layout: feature
 title: Custom queries
 parent: Writing queries
+permalink: /queries/custom
 ---
 
 # Custom statements

docs/docs/writing_queries/joins.md

@@ -7,4 +7,111 @@ permalink: /queries/joins
 ---
 
 # Joins
-TBD
+Moor supports sql joins to write queries that operate on more than one table. To use that feature, start
+a select regular select statement with `select(table)` and then add a list of joins using `.join()`. For
+inner and left outer joins, a `ON` expression needs to be specified. Here's an example using the tables
+defined in the [example]({{ site.common_links.getting_started | absolute_url }}).
+
+```dart
+// we define a data class to contain both a todo entry and the associated category
+class EntryWithCategory {
+  EntryWithCategory(this.entry, this.category);
+
+  final TodoEntry entry;
+  final Category category;
+}
+
+// in the database class, we can then load the category for each entry
+Stream<List<EntryWithCategory>> entriesWithCategory() {
+  final query = select(todos).join([
+    leftOuterJoin(categories, categories.id.equalsExp(todos.category)),
+  ]);
+
+  // see next section on how to parse the result
+}
+```
+
+## Parsing results
+Calling `get()` or `watch` on a select statement with join returns a `Future` or `Stream` of
+`List<TypedResult>` respectively. Each `TypedResult` represents a row from which data can be 
+read. It contains a `rawData` getter to obtain the raw row. But more importantly, the
+`readTable` method can be used to read a data class from a table.
+
+In the example query above, we can read the todo entry and the category from each row like this:
+```dart
+return query.watch().map((rows) {
+  return rows.map((row) {
+    return EntryWithCategory(
+      row.readTable(todos),
+      row.readTable(categories),
+    );
+  }).toList();
+});
+```
+
+_Note_: `readTable` returns `null` when an entity is not present in the row. For instance, todo entries
+might not be in any category. In that case, `row.readTable(categories)` returns `null`.
+## Aliases
+Sometimes, a query references a table more than once. Consider the following example to store saved routes for a
+navigation system:
+```dart
+class GeoPoints extends Table {
+  IntColumn get id => integer().autoIncrement()();
+  TextColumn get name => text()();
+  TextColumn get latitude => text()();
+  TextColumn get longitude => text()();
+}
+
+class Routes extends Table {
+
+  IntColumn get id => integer().autoIncrement()();
+  TextColumn get name => text()();
+
+  // contains the id for the start and destination geopoint.
+  IntColumn get start => integer()();
+  IntColumn get destination => integer()();
+}
+```
+
+Now, let's say we wanted to also load the start and destination `GeoPoint` object for each route. We'd have to use
+a join on the `geo-points` table twice: For the start and destination point. To express that in a query, aliases
+can be used:
+```dart
+class RouteWithPoints {
+  final Route route;
+  final GeoPoint start;
+  final GeoPoint destination;
+
+  RouteWithPoints({this.route, this.start, this.destination});
+}
+
+// inside the database class:
+Future<List<RouteWithPoints>> loadRoutes() async {
+  // create aliases for the geoPoints table so that we can reference it twice
+  final start = alias(geoPoints, 's');
+  final destination = alias(geoPoints, 'd');
+ 
+  final rows = await select(routes).join([
+    innerJoin(start, start.id.equalsExp(routes.start)),
+    innerJoin(destination, destination.id.equalsExp(routes.destination)),
+  ]).get();
+
+  return rows.map((resultRow) {
+    return RouteWithPoints(
+      route: resultRow.readTable(routes),
+      start: resultRow.readTable(start),
+      destination: resultRow.readTable(destination),
+    );
+  }).toList();
+}
+```
+The generated statement then looks like this:
+```sql
+SELECT 
+    routes.id, routes.name, routes.start, routes.destination,
+    s.id, s.name, s.latitude, s.longitude,
+    d.id, d.name, d.latitude, d.longitude 
+FROM routes 
+    INNER JOIN geo_points s ON s.id = routes.start
+    INNER JOIN geo_points d ON d.id = routes.destination
+```

moor/example/example.g.dart

@@ -49,8 +49,7 @@ class Category {
   }
 
   @override
-  int get hashCode =>
+  int get hashCode => $mrjf($mrjc($mrjc(0, id.hashCode), description.hashCode));
-      $moorjf($mrjf($mrjc(0, id.hashCode), description.hashCode));
   @override
   bool operator ==(other) =>
       identical(this, other) ||
@@ -180,9 +179,9 @@ class Recipe {
   }
 
   @override
-  int get hashCode => $moorjf($mrjf(
+  int get hashCode => $mrjf($mrjc(
-      $mrjf(
+      $mrjc(
-          $mrjf($mrjc(0, id.hashCode), title.hashCode), instructions.hashCode),
+          $mrjc($mrjc(0, id.hashCode), title.hashCode), instructions.hashCode),
       category.hashCode));
   @override
   bool operator ==(other) =>
@@ -337,8 +336,8 @@ class Ingredient {
   }
 
   @override
-  int get hashCode => $moorjf($mrjf(
+  int get hashCode => $mrjf($mrjc(
-      $mrjf($mrjc(0, id.hashCode), name.hashCode), caloriesPer100g.hashCode));
+      $mrjc($mrjc(0, id.hashCode), name.hashCode), caloriesPer100g.hashCode));
   @override
   bool operator ==(other) =>
       identical(this, other) ||
@@ -482,8 +481,8 @@ class IngredientInRecipe {
   }
 
   @override
-  int get hashCode => $moorjf($mrjf(
+  int get hashCode => $mrjf($mrjc(
-      $mrjf($mrjc(0, recipe.hashCode), ingredient.hashCode),
+      $mrjc($mrjc(0, recipe.hashCode), ingredient.hashCode),
       amountInGrams.hashCode));
   @override
   bool operator ==(other) =>

moor/lib/src/dsl/columns.dart

@@ -80,6 +80,11 @@ class ColumnBuilder<
   /// The column will use this expression when a row is inserted and no value
   /// has been specified.
   ///
+  /// Note: Unless most other methods used to declare tables, the parameter
+  /// [e] which denotes the default expression, doesn't have to be constant.
+  /// Particularly, you can use methods like [and], [or] and [not] to form
+  /// expressions here.
+  ///
   /// See also:
   /// - [Constant], which can be used to model literals that appear in CREATE
   /// TABLE statements.

moor/lib/src/runtime/statements/select.dart

@@ -118,7 +118,7 @@ class JoinedSelectStatement<FirstT, FirstD> extends Query<FirstT, FirstD>
         }
       }
 
-      return TypedResult(map);
+      return TypedResult(map, QueryRow(row, database));
     }).toList();
   }
 }
@@ -262,13 +262,15 @@ class CustomSelectStatement {
 /// entities.
 class TypedResult {
   /// Creates the result from the parsed table data.
-  TypedResult(this._data);
+  TypedResult(this._parsedData, this.rawData);
 
-  final Map<TableInfo, dynamic> _data;
+  final Map<TableInfo, dynamic> _parsedData;
+  /// The raw data contained in this row.
+  final QueryRow rawData;
 
   /// Reads all data that belongs to the given [table] from this row.
   D readTable<T, D>(TableInfo<T, D> table) {
-    return _data[table] as D;
+    return _parsedData[table] as D;
   }
 }
 

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

@@ -78,9 +78,9 @@ class TodoEntry {
   }
 
   @override
-  int get hashCode => $moorjf($mrjf(
+  int get hashCode => $mrjf($mrjc(
-      $mrjf(
+      $mrjc(
-          $mrjf($mrjf($mrjc(0, id.hashCode), title.hashCode), content.hashCode),
+          $mrjc($mrjc($mrjc(0, id.hashCode), title.hashCode), content.hashCode),
           targetDate.hashCode),
       category.hashCode));
   @override
@@ -251,8 +251,7 @@ class Category {
   }
 
   @override
-  int get hashCode =>
+  int get hashCode => $mrjf($mrjc($mrjc(0, id.hashCode), description.hashCode));
-      $moorjf($mrjf($mrjc(0, id.hashCode), description.hashCode));
   @override
   bool operator ==(other) =>
       identical(this, other) ||
@@ -398,10 +397,10 @@ class User {
   }
 
   @override
-  int get hashCode => $moorjf($mrjf(
+  int get hashCode => $mrjf($mrjc(
-      $mrjf(
+      $mrjc(
-          $mrjf(
+          $mrjc(
-              $mrjf($mrjc(0, id.hashCode), name.hashCode), isAwesome.hashCode),
+              $mrjc($mrjc(0, id.hashCode), name.hashCode), isAwesome.hashCode),
           profilePicture.hashCode),
       creationTime.hashCode));
   @override
@@ -567,7 +566,7 @@ class SharedTodo {
   }
 
   @override
-  int get hashCode => $moorjf($mrjf($mrjc(0, todo.hashCode), user.hashCode));
+  int get hashCode => $mrjf($mrjc($mrjc(0, todo.hashCode), user.hashCode));
   @override
   bool operator ==(other) =>
       identical(this, other) ||

moor_flutter/example/lib/database/database.g.dart

@@ -66,10 +66,10 @@ class TodoEntry {
   }
 
   @override
-  int get hashCode =>
+  int get hashCode => $mrjf($mrjc(
-      (((id.hashCode) * 31 + content.hashCode) * 31 + targetDate.hashCode) *
+      $mrjc(
-          31 +
+          $mrjc($mrjc(0, id.hashCode), content.hashCode), targetDate.hashCode),
-      category.hashCode;
+      category.hashCode));
   @override
   bool operator ==(other) =>
       identical(this, other) ||
@@ -221,7 +221,7 @@ class Category {
   }
 
   @override
-  int get hashCode => (id.hashCode) * 31 + description.hashCode;
+  int get hashCode => $mrjf($mrjc($mrjc(0, id.hashCode), description.hashCode));
   @override
   bool operator ==(other) =>
       identical(this, other) ||
@@ -300,8 +300,6 @@ abstract class _$Database extends GeneratedDatabase {
   $TodosTable get todos => _todos ??= $TodosTable(this);
   $CategoriesTable _categories;
   $CategoriesTable get categories => _categories ??= $CategoriesTable(this);
-  TodosDao _todosDao;
-  TodosDao get todosDao => _todosDao ??= TodosDao(this as Database);
   @override
   List<TableInfo> get allTables => [todos, categories];
 }

moor_generator/lib/src/writer/data_class_writer.dart

@@ -38,8 +38,6 @@ class DataClassWriter {
 
     _writeToString(buffer);
 
-    buffer.write('@override\n int get hashCode => ');
-
     _writeHashCode(buffer);
 
     // override ==
@@ -183,12 +181,14 @@ class DataClassWriter {
   }
 
   void _writeHashCode(StringBuffer buffer) {
+    buffer.write('@override\n int get hashCode => ');
+
     if (table.columns.isEmpty) {
       buffer.write('identityHashCode(this); \n');
     } else {
       final fields = table.columns.map((c) => c.dartGetterName).toList();
       buffer
-        ..write('\$moorjf(')
+        ..write('$_hashFinish(')
         ..write(_calculateHashCode(fields))
         ..write(')')
         ..write('; \n');
@@ -206,7 +206,7 @@ class DataClassWriter {
       final last = fields.removeLast();
       final innerHash = _calculateHashCode(fields);
 
-      return '$_hashFinish($innerHash, $last.hashCode)';
+      return '$_hashCombine($innerHash, $last.hashCode)';
     }
   }
 }