Added bookstore example

Author: joente

examples/bookstore/bookstore.py

@@ -0,0 +1,130 @@
+"""Keep data in sync between multiple services using ThingsDB.
+
+Make sure you start with an empty collection and configure your token and
+collection. (THINGSDB_AUTH_TOKEN and THINGSDB_COLLECTION)
+
+Start the `bookstore.py` multiple times on different ports, for example:
+
+python bookstore.py 5050
+python bookstore.py 5051
+
+Call the `add_book` handler on the one of the web servers (For example 5050)
+```
+curl \
+    --location \
+    --request POST 'http://127.0.0.1:5050/add_book' \
+    --header 'Content-Type: application/json' \
+    --data-raw '{"title": "A short history of nearly everything"}'
+```
+
+Observe that the book is synchronized with the other web server (5051):
+
+```
+curl \
+    --location \
+    --request GET 'http://127.0.0.1:5051/get_books'
+```
+"""
+from sys import argv
+from functools import partial
+from asyncio import get_event_loop
+from aiohttp import web
+from thingsdb.client import Client
+from thingsdb.room import Room, event
+
+THINGSDB_AUTH_TOKEN = 'YOUR_TOKEN'
+THINGSDB_COLLECTION = '//YOUR_COLLECTION'
+
+bookstore = None
+
+
+class BookStore(Room):
+
+    def on_init(self):
+        self.books = []
+        self.add_book = partial(self.client.run, 'add_book')
+
+    async def on_join(self):
+        self.books = await self.client.query("""//ti
+            .books;  // Just return all the books
+        """)
+
+    @event('add-book')
+    def on_add_boook(self, book):
+        self.books.append(book)
+
+
+def on_cleanup():
+    client.close()
+    return client.wait_closed()
+
+
+async def add_book(request):
+    book = await request.json()
+    # Use the procedure to add the book
+    await bookstore.add_book(book)
+    return web.HTTPNoContent()
+
+
+# We hve the books in memory
+async def get_books(request):
+    return web.json_response({
+        "book_titles": [book['title'] for book in bookstore.books]
+    })
+
+
+async def setup(client):
+    global bookstore
+
+    await client.connect('playground.thingsdb.net', '9400')
+    await client.authenticate(THINGSDB_AUTH_TOKEN)
+
+    bookstore = BookStore("""//ti
+        if (!has_type('Book')) {
+
+            new_procedure('add_book', |book| {
+                book = Book(book);
+                .books.push(book);  // add the book to our books list
+                .ev.emit('add-book', book);  // emit the add-book event
+            });
+
+            // Set-up the collection, this will run only the first time.
+            set_type('Book', {
+                title: 'str',
+            });
+
+            set_type('BookStore', {
+                books: '[Book]',
+                ev: 'room',
+            });
+
+            // Convert the collection to type BookStore. This works
+            // only on an empty collection, if the collectoins is not empty
+            // you can use .clear(); first to empty the collection.
+            .to_type('BookStore');
+        };
+
+        .ev.id();  // Return the event room id
+    """)
+    await bookstore.join(client)
+
+
+if __name__ == '__main__':
+    port = int(argv[1])
+
+    app = web.Application()
+
+    # Handlers
+    app.add_routes([
+        web.post("/add_book", add_book),
+        web.get("/get_books", get_books),
+    ])
+
+    client = Client(ssl=True)
+    client.set_default_scope(THINGSDB_COLLECTION)
+
+    loop = get_event_loop()
+    loop.run_until_complete(setup(client))
+
+    app.on_cleanup.append(lambda _: on_cleanup())
+    web.run_app(app, port=port, loop=loop)