Add appengine/gcloud/mustache dependencies.

pkg/gcloud/lib/src/db/annotations.dart

Index: pkg/gcloud/lib/src/db/annotations.dart
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+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of gcloud.db;
+
+/// Annotation used to mark dart classes which can be stored into datastore.
+///
+/// The `Kind` annotation on a class as well as other `Property` annotations on
+/// fields or getters of the class itself (and any of it's superclasses) up to
+/// the [Model] class describe the *mapping* of *dart objects* to datastore
+/// *entities*.
+///
+/// An "entity" is an object which can be stored into Google Cloud Datastore.
+/// It contains a number of named "properties", some of them might get indexed,
+/// others are not. A "property" value can be of a limited set of supported
+/// types (such as `int` and `String`).
+///
+/// Here is an example of a dart model class which can be stored into datastore:
+///     @Kind()
+///     class Person extends db.Model {
+///       @StringProperty()
+///       String name;
+///
+///       @IntProperty()
+///       int age;
+///
+///       @DateTimeProperty()
+///       DateTime dateOfBirth;
+///     }
+class Kind {
+  /// The kind name used when saving objects to datastore.
+  ///
+  /// If `null` the name will be the same as the class name at which the
+  /// annotation is placed.
+  final String name;
+
+  /// The type, either [ID_TYPE_INTEGER] or [ID_TYPE_STRING].
+  final IdType idType;
+
+  /// Annotation specifying the name of this kind and whether to use integer or
+  /// string `id`s.
+  ///
+  /// If `name` is omitted, it will default to the name of class to which this
+  /// annotation is attached to.
+  const Kind({this.name, this.idType: IdType.Integer});
+}
+
+/// The type used for id's of an entity.
+class IdType {
+  /// Use integer ids for identifying entities.
+  static const IdType Integer = const IdType(1);
+
+  /// Use string ids for identifying entities.
+  static const IdType String = const IdType(2);
+
+  final int _type;
+
+  const IdType(this._type);
+}
+
+/// Describes a property of an Entity.
+///
+/// Please see [Kind] for an example on how to use them.
+abstract class Property {
+  /// The name of the property.
+  ///
+  /// If it is `null`, the name will be the same as used in the
+  /// model class.
+  final String propertyName;
+
+  /// Specifies whether this property is required or not.
+  ///
+  /// If required is `true`, it will be enforced when saving model objects to
+  /// the datastore and when retrieving them.
+  final bool required;
+
+  /// Specifies whether this property should be indexed or not.
+  ///
+  /// When running queries no this property, it is necessary to set [indexed] to
+  /// `true`.
+  final bool indexed;
+
+  const Property({this.propertyName, this.required: false, this.indexed: true});
+
+  bool validate(ModelDB db, Object value) {
+    if (required && value == null) return false;
+    return true;
+  }
+
+  Object encodeValue(ModelDB db, Object value);
+
+  Object decodePrimitiveValue(ModelDB db, Object value);
+}
+
+/// An abstract base class for primitive properties which can e.g. be used
+/// within a composed `ListProperty`.
+abstract class PrimitiveProperty extends Property {
+  const PrimitiveProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  Object encodeValue(ModelDB db, Object value) => value;
+
+  Object decodePrimitiveValue(ModelDB db, Object value) => value;
+}
+
+/// A boolean [Property].
+///
+/// It will validate that values are booleans before writing them to the
+/// datastore and when reading them back.
+class BoolProperty extends PrimitiveProperty {
+  const BoolProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is bool);
+}
+
+/// A integer [Property].
+///
+/// It will validate that values are integers before writing them to the
+/// datastore and when reading them back.
+class IntProperty extends PrimitiveProperty {
+  const IntProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is int);
+}
+
+/// A double [Property].
+///
+/// It will validate that values are doubles before writing them to the
+/// datastore and when reading them back.
+class DoubleProperty extends PrimitiveProperty {
+  const DoubleProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is double);
+}
+
+/// A string [Property].
+///
+/// It will validate that values are strings before writing them to the
+/// datastore and when reading them back.
+class StringProperty extends PrimitiveProperty {
+  const StringProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is String);
+}
+
+/// A key [Property].
+///
+/// It will validate that values are keys before writing them to the
+/// datastore and when reading them back.
+class ModelKeyProperty extends PrimitiveProperty {
+  const ModelKeyProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is Key);
+
+  Object encodeValue(ModelDB db, Object value) {
+    if (value == null) return null;
+    return db.toDatastoreKey(value);
+  }
+
+  Object decodePrimitiveValue(ModelDB db, Object value) {
+    if (value == null) return null;
+    return db.fromDatastoreKey(value as datastore.Key);
+  }
+}
+
+/// A binary blob [Property].
+///
+/// It will validate that values are blobs before writing them to the
+/// datastore and when reading them back. Blob values will be represented by
+/// List<int>.
+class BlobProperty extends PrimitiveProperty {
+  const BlobProperty({String propertyName, bool required: false})
+     : super(propertyName: propertyName, required: required, indexed: false);
+
+  // NOTE: We don't validate that the entries of the list are really integers
+  // of the range 0..255!
+  // If an untyped list was created the type check will always succeed. i.e.
+  //   "[1, true, 'bar'] is List<int>" evaluates to `true`
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is List<int>);
+
+  Object encodeValue(ModelDB db, Object value) {
+      if (value == null) return null;
+      return new datastore.BlobValue(value);
+  }
+
+  Object decodePrimitiveValue(ModelDB db, Object value) {
+    if (value == null) return null;
+
+    datastore.BlobValue blobValue = value;
+    return blobValue.bytes;
+  }
+}
+
+/// A datetime [Property].
+///
+/// It will validate that values are DateTime objects before writing them to the
+/// datastore and when reading them back.
+class DateTimeProperty extends PrimitiveProperty {
+  const DateTimeProperty(
+      {String propertyName, bool required: false, bool indexed: true})
+      : super(propertyName: propertyName, required: required, indexed: indexed);
+
+  bool validate(ModelDB db, Object value)
+      => super.validate(db, value) && (value == null || value is DateTime);
+
+  Object decodePrimitiveValue(ModelDB db, Object value) {
+    if (value is int) {
+      return
+          new DateTime.fromMillisecondsSinceEpoch(value ~/ 1000, isUtc: true);
+    }
+    return value;
+  }
+}
+
+
+/// A composed list [Property], with a `subProperty` for the list elements.
+///
+/// It will validate that values are List objects before writing them to the
+/// datastore and when reading them back. It will also validate the elements
+/// of the list itself.
+class ListProperty extends Property {
+  final PrimitiveProperty subProperty;
+
+  // TODO: We want to support optional list properties as well.
+  // Get rid of "required: true" here.
+  const ListProperty(this.subProperty,
+                     {String propertyName, bool indexed: true})
+      : super(propertyName: propertyName, required: true, indexed: indexed);
+
+  bool validate(ModelDB db, Object value) {
+    if (!super.validate(db, value) || value is! List) return false;
+
+    for (var entry in value) {
+       if (!subProperty.validate(db, entry)) return false;
+    }
+    return true;
+  }
+
+  Object encodeValue(ModelDB db, Object value) {
+    if (value == null) return null;
+    List list = value;
+    if (list.length == 0) return null;
+    if (list.length == 1) return subProperty.encodeValue(db, list[0]);
+    return list.map(
+        (value) => subProperty.encodeValue(db, value)).toList();
+  }
+
+  Object decodePrimitiveValue(ModelDB db, Object value) {
+    if (value == null) return [];
+    if (value is! List) return [subProperty.decodePrimitiveValue(db, value)];
+    return (value as List)
+        .map((entry) => subProperty.decodePrimitiveValue(db, entry))
+        .toList();
+  }
+}
+
+/// A convenience [Property] for list of strings.
+class StringListProperty extends ListProperty {
+  const StringListProperty({String propertyName, bool indexed: true})
+      : super(const StringProperty(),
+              propertyName: propertyName, indexed: indexed);
+}