Generate code for nested results (#288)

moor/lib/src/runtime/query_builder/query_builder.dart

@@ -5,7 +5,7 @@ import 'package:collection/collection.dart';
 import 'package:meta/meta.dart';
 // hidden because of https://github.com/dart-lang/sdk/issues/39262
 import 'package:moor/moor.dart'
-    hide BooleanExpressionOperators, DateTimeExpressions;
+    hide BooleanExpressionOperators, DateTimeExpressions, TableInfoUtils;
 import 'package:moor/sqlite_keywords.dart';
 import 'package:moor/src/runtime/executor/stream_queries.dart';
 import 'package:moor/src/runtime/types/sql_types.dart';

moor/lib/src/runtime/query_builder/schema/table_info.dart

@@ -32,17 +32,6 @@ mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table
   @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".
-  String get tableWithAlias {
-    if ($tableName == actualTableName) {
-      return actualTableName;
-    } else {
-      return '$actualTableName ${$tableName}';
-    }
-  }
-
   /// All columns defined in this table.
   List<GeneratedColumn> get $columns;
 
@@ -74,11 +63,6 @@ mixin TableInfo<TableDsl extends Table, D extends DataClass> on Table
   /// Maps the given row returned by the database into the fitting data class.
   D map(Map<String, dynamic> data, {String tablePrefix});
 
-  /// Like [map], but from a [row] instead of the low-level map.
-  D mapFromRow(QueryRow row, {String tablePrefix}) {
-    return map(row.data, tablePrefix: tablePrefix);
-  }
-
   /// Converts a [companion] to the real model class, [D].
   ///
   /// Values that are [Value.absent] in the companion will be set to `null`.
@@ -113,3 +97,39 @@ mixin VirtualTableInfo<TableDsl extends Table, D extends DataClass>
   /// USING <moduleAndArgs>;` can be used to create this table in sql.
   String get moduleAndArgs;
 }
+
+/// Static extension members for generated table classes.
+///
+/// Most of these are accessed internally by moor or by generated code.
+extension TableInfoUtils<TableDsl extends Table, D extends DataClass>
+    on TableInfo<TableDsl, D> {
+  /// 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".
+  String get tableWithAlias {
+    if ($tableName == actualTableName) {
+      return actualTableName;
+    } else {
+      return '$actualTableName ${$tableName}';
+    }
+  }
+
+  /// Like [map], but from a [row] instead of the low-level map.
+  D mapFromRow(QueryRow row, {String tablePrefix}) {
+    return map(row.data, tablePrefix: tablePrefix);
+  }
+
+  /// Like [mapFromRow], but returns null if a non-nullable column of this table
+  /// is null in [row].
+  D /*?*/ mapFromRowOrNull(QueryRow row, {String tablePrefix}) {
+    final resolvedPrefix = tablePrefix ?? '';
+
+    final notInRow = $columns
+        .where((c) => !c.$nullable)
+        .any((e) => row.data['$resolvedPrefix'] == null);
+
+    if (notInRow) return null;
+
+    return mapFromRow(row, tablePrefix: tablePrefix);
+  }
+}

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

@@ -1196,16 +1196,14 @@ abstract class _$CustomTablesDb extends GeneratedDatabase {
     return MultipleResult(
       a: row.readString('a'),
       b: row.readInt('b'),
-      c: row.readDouble('c'),
-      a1: row.readString('a'),
-      b1: row.readInt('b'),
+      c: withConstraints.mapFromRowOrNull(row, tablePrefix: 'nested_0'),
     );
   }
 
   Selectable<MultipleResult> multiple(Expression<bool> predicate) {
     final generatedpredicate = $write(predicate, hasMultipleTables: true);
     return customSelect(
-        'SELECT * FROM with_constraints c\n INNER JOIN with_defaults d\n   ON d.a = c.a AND d.b = c.b\n WHERE ${generatedpredicate.sql}',
+        'SELECT d.*, "c.a" AS "nested_0.a", "c.b" AS "nested_0.b", "c.c" AS "nested_0.c" FROM with_constraints c\n INNER JOIN with_defaults d\n   ON d.a = c.a AND d.b = c.b\n WHERE ${generatedpredicate.sql}',
         variables: [...generatedpredicate.introducedVariables],
         readsFrom: {withConstraints, withDefaults}).map(_rowToMultipleResult);
   }
@@ -1306,28 +1304,21 @@ class TableValuedResult {
 class MultipleResult {
   final String a;
   final int b;
-  final double c;
-  final String a1;
-  final int b1;
+  final WithConstraint c;
   MultipleResult({
     this.a,
     this.b,
     this.c,
-    this.a1,
-    this.b1,
   });
   @override
-  int get hashCode => $mrjf($mrjc(a.hashCode,
-      $mrjc(b.hashCode, $mrjc(c.hashCode, $mrjc(a1.hashCode, b1.hashCode)))));
+  int get hashCode => $mrjf($mrjc(a.hashCode, $mrjc(b.hashCode, c.hashCode)));
   @override
   bool operator ==(dynamic other) =>
       identical(this, other) ||
       (other is MultipleResult &&
           other.a == this.a &&
           other.b == this.b &&
-          other.c == this.c &&
-          other.a1 == this.a1 &&
-          other.b1 == this.b1);
+          other.c == this.c);
 }
 
 class ReadRowIdResult {

moor/test/data/tables/tables.moor

@@ -49,7 +49,7 @@ tableValued:
 
 @create: INSERT INTO config (config_key, config_value) VALUES ('key', 'values');
 
-multiple: SELECT * FROM with_constraints c
+multiple: SELECT d.*, c.** FROM with_constraints c
  INNER JOIN with_defaults d
    ON d.a = c.a AND d.b = c.b
  WHERE $predicate;

moor_generator/lib/src/analyzer/sql_queries/query_handler.dart

@@ -170,7 +170,8 @@ class QueryHandler {
         if (result is! Table) continue;
 
         final moorTable = mapper.tableToMoor(result as Table);
-        nestedTables.add(NestedResultTable(column.tableName, moorTable));
+        nestedTables
+            .add(NestedResultTable(column, column.tableName, moorTable));
       }
     }
 

moor_generator/lib/src/model/sql_query.dart

@@ -167,7 +167,8 @@ class InferredResultSet {
 
   /// Whether this query returns a single column that should be returned
   /// directly.
-  bool get singleColumn => matchingTable == null && columns.length == 1;
+  bool get singleColumn =>
+      matchingTable == null && nestedResults.isEmpty && columns.length == 1;
 
   void forceDartNames(Map<ResultColumn, String> names) {
     _dartNames
@@ -251,10 +252,13 @@ class ResultColumn {
 /// Knowing that `User` should be extracted into a field is represented with a
 /// [NestedResultTable] information as part of the result set.
 class NestedResultTable {
+  final NestedStarResultColumn from;
   final String name;
   final MoorTable table;
 
-  NestedResultTable(this.name, this.table);
+  NestedResultTable(this.from, this.name, this.table);
+
+  String get dartFieldName => ReCase(name).camelCase;
 }
 
 /// Something in the query that needs special attention when generating code,

moor_generator/lib/src/writer/queries/query_writer.dart

@@ -19,6 +19,8 @@ class QueryWriter {
   final SqlQuery query;
   final Scope scope;
 
+  final Map<NestedResultTable, String> _expandedNestedPrefixes = {};
+
   SqlSelectQuery get _select => query as SqlSelectQuery;
   UpdatingQuery get _update => query as UpdatingQuery;
 
@@ -64,6 +66,7 @@ class QueryWriter {
   }
 
   void _writeSelect() {
+    _createNamesForNestedResults();
     if (!_select.resultSet.singleColumn) {
       _writeMapping();
     }
@@ -88,6 +91,14 @@ class QueryWriter {
     }
   }
 
+  void _createNamesForNestedResults() {
+    var index = 0;
+
+    for (final nested in _select.resultSet.nestedResults) {
+      _expandedNestedPrefixes[nested] = 'nested_${index++}';
+    }
+  }
+
   /// Writes a mapping method that turns a "QueryRow" into the desired custom
   /// return type.
   void _writeMapping() {
@@ -106,6 +117,16 @@ class QueryWriter {
         final fieldName = _select.resultSet.dartNameFor(column);
         _buffer.write('$fieldName: ${_readingCode(column)},');
       }
+      for (final nested in _select.resultSet.nestedResults) {
+        final prefix = _expandedNestedPrefixes[nested];
+        if (prefix == null) continue;
+
+        final fieldName = nested.dartFieldName;
+        final tableGetter = nested.table.dbGetterName;
+
+        _buffer.write('$fieldName: $tableGetter.mapFromRowOrNull(row, '
+            'tablePrefix: ${asDartLiteral(prefix)}),');
+      }
       _buffer.write(');\n}\n');
 
       _writtenMappingMethods.add(_nameOfMappingMethod());
@@ -354,12 +375,25 @@ class QueryWriter {
   String _queryCode() {
     // sort variables and placeholders by the order in which they appear
     final toReplace = query.fromContext.root.allDescendants
-        .where((node) => node is Variable || node is DartPlaceholder)
+        .where((node) =>
+            node is Variable ||
+            node is DartPlaceholder ||
+            node is NestedStarResultColumn)
         .toList()
           ..sort(_compareNodes);
 
     final buffer = StringBuffer("'");
 
+    // Index nested results by their syntactic origin for faster lookups later
+    var doubleStarColumnToResolvedTable =
+        const <NestedStarResultColumn, NestedResultTable>{};
+    if (query is SqlSelectQuery) {
+      doubleStarColumnToResolvedTable = {
+        for (final nestedResult in _select.resultSet.nestedResults)
+          nestedResult.from: nestedResult
+      };
+    }
+
     var lastIndex = query.fromContext.root.firstPosition;
 
     void replaceNode(AstNode node, String content) {
@@ -387,6 +421,29 @@ class QueryWriter {
 
         replaceNode(rewriteTarget,
             '\${${_placeholderContextName(moorPlaceholder)}.sql}');
+      } else if (rewriteTarget is NestedStarResultColumn) {
+        final result = doubleStarColumnToResolvedTable[rewriteTarget];
+        if (result == null) continue;
+
+        final prefix = _expandedNestedPrefixes[result];
+        final table = rewriteTarget.tableName;
+
+        // Convert foo.** to "foo.a" AS "nested_0.a", ... for all columns in foo
+        final expanded = StringBuffer();
+        var isFirst = true;
+
+        for (final column in result.table.columns) {
+          if (isFirst) {
+            isFirst = false;
+          } else {
+            expanded.write(', ');
+          }
+
+          final columnName = column.name.name;
+          expanded.write('"$table.$columnName" AS "$prefix.$columnName"');
+        }
+
+        replaceNode(rewriteTarget, expanded.toString());
       }
     }
 

moor_generator/lib/src/writer/queries/result_set_writer.dart

@@ -10,8 +10,7 @@ class ResultSetWriter {
 
   void write() {
     final className = query.resultClassName;
-    final columnNames =
-        query.resultSet.columns.map(query.resultSet.dartNameFor).toList();
+    final fieldNames = <String>[];
     final into = scope.leaf();
 
     into.write('class $className {\n');
@@ -20,11 +19,22 @@ class ResultSetWriter {
       final name = query.resultSet.dartNameFor(column);
       final runtimeType = column.dartType;
       into.write('final $runtimeType $name\n;');
+
+      fieldNames.add(name);
+    }
+
+    for (final nested in query.resultSet.nestedResults) {
+      final typeName = nested.table.dartTypeName;
+      final fieldName = nested.dartFieldName;
+
+      into.write('final $typeName $fieldName;\n');
+
+      fieldNames.add(fieldName);
     }
 
     // write the constructor
     into.write('$className({');
-    for (final column in columnNames) {
+    for (final column in fieldNames) {
       into.write('this.$column,');
     }
     into.write('});\n');
@@ -32,10 +42,10 @@ class ResultSetWriter {
     // if requested, override hashCode and equals
     if (scope.writer.options.overrideHashAndEqualsInResultSets) {
       into.write('@override int get hashCode => ');
-      const HashCodeWriter().writeHashCode(columnNames, into);
+      const HashCodeWriter().writeHashCode(fieldNames, into);
       into.write(';\n');
 
-      overrideEquals(columnNames, className, into);
+      overrideEquals(fieldNames, className, into);
     }
 
     into.write('}\n');