1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Copyright 2016 Alexandre Terrasa <alexandre@moz-code.org>
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
17 # Repositories for data management.
19 # Repositories are used to apply persistence on instances (or **documents**).
20 # Using repositories one can store and retrieve instance in a clean and maintenable
23 # This module provides the base interface `Repository` that defines the persistence
24 # services available in all kind of repos.
25 # `JsonRepository` factorizes all repositories dedicated to Json data or objects
26 # serializable to Json.
28 # `MongoRepository` is provided as a concrete example of repository.
29 # It implements all the services from `Repository` using a Mongo database as backend.
31 # Repositories can be used in Popcorn app to manage your data persistence.
32 # Here an example with a book management app:
35 # # First we declare the `Book` class. It has to be serializable so it can be used
36 # # within a `Repository`.
39 # import popcorn::pop_repos
41 # # Serializable book representation.
47 # var id: String = (new MongoObjectId).id is serialize_as "_id"
54 # redef fun to_s do return title
55 # redef fun ==(o) do return o isa SELF and id == o.id
56 # redef fun hash do return id.hash
57 # redef fun to_json do return serialize_to_json
60 # # We then need to subclass the `MongoRepository` to provide Book specific services.
62 # # Book repository for Mongo
64 # super MongoRepository[Book]
66 # # Find books by title
67 # fun find_by_title(title: String): Array[Book] do
68 # var q = new JsonObject
74 # # The repository can be used in a Handler to manage book in a REST API.
81 # # Return a json array of all books
83 # # If the get parameters `title` is provided, returns a json array of books
84 # # matching the `title`.
85 # redef fun get(req, res) do
86 # var title = req.string_arg("title")
87 # if title == null then
88 # res.json new JsonArray.from(repo.find_all)
90 # res.json new JsonArray.from(repo.find_by_title(title))
95 # redef fun post(req, res) do
96 # var title = req.string_arg("title")
97 # if title == null then
101 # var book = new Book(title)
107 # # Let's wrap it all together in a Popcorn app:
110 # var mongo = new MongoClient("mongodb://localhost:27017/")
111 # var db = mongo.database("tests_app_{100000.rand}")
112 # var coll = db.collection("books")
116 # var repo = new BookRepo(coll)
117 # app.use("/books", new BookHandler(repo))
118 # app.listen("localhost", 3000)
123 import json
::serialization
124 import mongodb
::queries
126 # A Repository is an object that can store serialized instances.
128 # Repository is the base class of all kind of persistance processes. It offers
129 # the base CRUD services to save (add/update), find and delete instances.
131 # Instances are stored in their serialized form. See the `serialization` package
132 # for more documentation.
133 interface Repository[E
: Serializable]
135 # Kind of queries accepted
137 # Can be redefined to accept more precise queries depending on the backend used.
138 type QUERY: RepositoryQuery
140 # Find an instance by it's `id`
142 # `id` is an abstract thing at this stage
143 # TODO maybe introduce the `PrimaryKey` concept?
144 fun find_by_id
(id
: String): nullable E
is abstract
146 # Find an instance based on `query`
147 fun find
(query
: QUERY): nullable E
is abstract
149 # Find all instances based on `query`
151 # Using `query` == null will retrieve all the document in the repository.
152 fun find_all
(query
: nullable QUERY): Array[E
] is abstract
155 fun save
(instance
: E
): Bool is abstract
157 # Remove the instance with `id`
158 fun remove_by_id
(id
: String): Bool is abstract
160 # Remove the instance based on `query`
161 fun remove
(query
: nullable QUERY): Bool is abstract
163 # Remove all the instances matching on `query`
164 fun remove_all
(query
: nullable QUERY): Bool is abstract
166 # Remove all instances
167 fun clear
: Bool is abstract
169 # Serialize an `instance` to a String.
170 fun serialize
(instance
: nullable E
): nullable String is abstract
172 # Deserialize a `string` to an instance.
173 fun deserialize
(string
: nullable String): nullable E
is abstract
176 # An abstract Query representation.
178 # Since the kind of query available depends on the database backend choice or
179 # implementation, this interface is used to provide a common type to all the
182 # Redefine `Repository::QUERY` to use your own kind of query.
183 interface RepositoryQuery end
185 # A Repository for JsonObjects.
187 # As for document oriented databases, Repository can be used to store and retrieve
189 # Serialization from/to Json is used to translate from/to nit instances.
191 # See `MongoRepository` for a concrete implementation example.
192 abstract class JsonRepository[E
: Serializable]
195 redef fun serialize
(item
) do
196 if item
== null then return null
197 var stream
= new StringWriter
198 var serializer
= new RepoSerializer(stream
)
199 serializer
.serialize item
204 redef fun deserialize
(string
) do
205 if string
== null then return null
206 var deserializer
= new JsonDeserializer(string
)
207 return deserializer
.deserialize
.as(E
)
211 private class RepoSerializer
214 # Remove caching when saving refs to db
215 redef fun serialize_reference
(object
) do serialize object
218 # A Repository that uses MongoDB as backend.
222 # import popcorn::pop_repos
224 # # First, let's create a User abstraction:
226 # # Serializable user representation.
235 # var password: String is writable
237 # redef fun to_s do return login
240 # # We then need to subclass the `MongoRepository` to provide User specific services:
242 # # User repository for Mongo
244 # super MongoRepository[User]
246 # # Find a user by its login
247 # fun find_by_login(login: String): nullable User do
248 # var q = new JsonObject
254 # # The repository can then be used with User instances:
257 # var mongo = new MongoClient("mongodb://localhost:27017/")
258 # var db = mongo.database("tests")
259 # var coll = db.collection("test_pop_repo_{100000.rand}")
261 # # Create a user repo to store User instances
262 # var repo = new UserRepo(coll)
264 # # Create some users
265 # repo.save(new User("Morriar", "1234"))
266 # repo.save(new User("Alex", "password"))
268 # assert repo.find_all.length == 2
269 # assert repo.find_by_login("Morriar").password == "1234"
271 # assert repo.find_all.length == 0
273 class MongoRepository[E
: Serializable]
274 super JsonRepository[E
]
276 redef type QUERY: JsonObject
278 # MongoDB collection used to store objects
279 var collection
: MongoCollection
281 redef fun find_by_id
(id
) do
282 var query
= new JsonObject
287 redef fun find
(query
) do
288 var res
= collection
.find
(query
)
289 if res
== null then return null
290 return deserialize
(res
.to_json
)
293 redef fun find_all
(query
) do
294 var res
= new Array[E
]
295 for e
in collection
.find_all
(query
or else new JsonObject) do
296 res
.add deserialize
(e
.to_json
).as(E
)
301 redef fun save
(item
) do
302 var json
= serialize
(item
).as(String)
303 var obj
= json
.parse_json
.as(JsonObject)
304 return collection
.save
(obj
)
307 redef fun remove_by_id
(id
) do
308 var query
= new JsonObject
313 redef fun remove
(query
) do
314 return collection
.remove
(query
or else new JsonObject)
317 redef fun remove_all
(query
) do
318 return collection
.remove_all
(query
or else new JsonObject)
321 redef fun clear
do return collection
.drop
323 # Perform an aggregation query over the repo.
324 fun aggregate
(pipeline
: JsonArray): Array[E
] do
325 var res
= new Array[E
]
326 for obj
in collection
.aggregate
(pipeline
) do
327 var instance
= deserialize
(obj
.to_json
)
328 if instance
== null then continue
335 # Base serializable entity that can go into a JsonRepository
337 # Provide boiler plate implementation of all object serializable to json.
339 # `id` is used as a primary key for `find_by_id`.
341 # Subclassing RepoObject makes it easy to create a serializable class:
343 # import popcorn::pop_repos
354 # Do not forget the `serialize` annotation else the fields will not be serialized.
356 # It is also possible to redefine the `id` primary key to use your own:
358 # import popcorn::pop_repos
364 # redef var id = "order-{get_time}"
370 abstract class RepoObject
376 # This attribute is serialized under the key `_id` to be used
377 # as primary key by MongoDb
378 var id
: String = (new MongoObjectId).id
is writable, serialize_as
"_id"
380 # Base object comparison on ID
382 # Because multiple deserialization can exists of the same instance,
383 # we use the ID to determine if two object are the same.
384 redef fun ==(o
) do return o
isa SELF and id
== o
.id
386 redef fun hash
do return id
.hash
387 redef fun to_s
do return id
388 redef fun to_json
do return serialize_to_json
391 # JsonObject can be used as a `RepositoryQuery`.
394 redef class JsonObject
395 super RepositoryQuery