Send SSE

isbn_sort/app.py

@@ -1,12 +1,26 @@
-from flask import render_template, redirect, request, flash, Blueprint, current_app, url_for
+from flask import render_template, redirect, request, flash, Blueprint, current_app, url_for, Response
 
 import json
 
 from .book import Book
 from . import isbn_db
+from . import sse
 
 bp = Blueprint("app", __name__, url_prefix="/app")
 
+announcer = sse.MessageAnnouncer()
+
+def announce_book(book, msg_type: str="add_book") -> None:
+    """
+    msg_type must either be "update_book",  "add_book" or "delete_book"
+    """
+    msg = sse.format_sse({
+        "type": msg_type,
+        "book": book.to_json()
+    })
+    announcer.announce(msg)
+
+
 @bp.route("/submit-isbn")
 def submit_isbn():
     if "isbn" not in request.args:
@@ -24,18 +38,23 @@ def submit_isbn():
         book.load()
     except KeyError:
         isbn_db.add_book(book)
+        announce_book(book)
         return "Pas trouvé, à rajouter manuellement"
 
     print("Got ", book)
     if isbn_db.add_book(book) == "duplicate":
+        announce_book(book, msg_type="update_book")
         return f"{book.title} ajouté (plusieurs occurrences)"
+    announce_book(book)
     return f"{book.title} ajouté"
 
+
 @bp.route("/web-submit-isbn")
 def web_submit_isbn():
     flash(submit_isbn())
     return redirect(url_for("app.index"))
 
+
 @bp.route("/")
 def index():
     return render_template("index.html", books=isbn_db.get_all_books())
@@ -47,8 +66,16 @@ def delete_book():
         return "missing isbn"
 
     isbn_db.delete_book(request.form["isbn"])
+    msg = sse.format_sse({
+        "type": "delete_book",
+        "book": {
+            "isbn": request.form["isbn"]
+        }
+    })
+    announcer.announce(msg)
     return redirect(url_for("app.index"))
 
+
 @bp.route("/update-book", methods=["POST"])
 def update_book():
     attributes = ["isbn", "count", "title", "author", "publisher", "publish_date"]
@@ -70,8 +97,10 @@ def update_book():
         count=int(form_data["count"])
     )
     isbn_db.update_book(book)
+    announce_book(book, msg_type="update_book")
     return redirect(url_for("app.index"))
 
+
 @bp.route("/export-csv")
 def export_csv():
     books = isbn_db.get_all_books()
@@ -86,3 +115,21 @@ def export_csv():
         mimetype="text/csv",
         headers={"Content-Disposition": "attachment;filename=books.csv"}
     )
+
+
+@bp.route('/listen', methods=['GET'])
+def listen():
+    def stream():
+        messages = announcer.listen()  # returns a queue.Queue
+        while True:
+            msg = messages.get()  # blocks until a new message arrives
+            yield msg
+
+    return Response(stream(), mimetype='text/event-stream')
+
+
+@bp.route('/ping')
+def ping():
+    msg = sse.format_sse(data={"type": "pong"})
+    announcer.announce(msg=msg)
+    return {}, 200

isbn_sort/book.py

@@ -58,3 +58,13 @@ class Book:
         if self.title is None:
             return f"<Book: ISBN:{self.isbn}>"
         return f"<Book: {self.title}>"
+
+    def to_json(self):
+        return {
+            "isbn": self.isbn,
+            "title": self.title,
+            "publisher": self.publisher,
+            "publish_date": self.publish_date,
+            "author": self.author,
+            "count": self.count
+        }

isbn_sort/sse.py

@@ -0,0 +1,26 @@
+import queue
+import json
+
+class MessageAnnouncer:
+    def __init__(self):
+        self.listeners = []
+
+    def listen(self):
+        q = queue.Queue(maxsize=5)
+        self.listeners.append(q)
+        return q
+
+    def announce(self, msg):
+        for i in reversed(range(len(self.listeners))):
+            try:
+                self.listeners[i].put_nowait(msg)
+            except queue.Full:
+                del self.listeners[i]
+
+
+def format_sse(data: str, event=None) -> str:
+    json_data = json.dumps(data)
+    msg = f'data: {json_data}\n\n'
+    if event is not None:
+        msg = f'event: {event}\n{msg}'
+    return msg

isbn_sort/static/dynamicUpdate.js

@@ -0,0 +1,23 @@
+const listener = new EventSource("/app/listen");
+
+listener.onmessage = (e) => {
+    let data = JSON.parse(e.data);
+    console.log(data);
+    
+    switch (data.type) {
+        case "pong":
+            console.log("pong!");
+            break;
+        case "add_book":
+            viewAddBook(data.book);
+            break;
+        case "update_book":
+            viewUpdateBook(data.book);
+            break;
+        case "delete_book":
+            viewDeleteBook(data.book);
+            break;
+        default:
+            console.log("Unexpected response from SSE:", data);
+    }
+};

isbn_sort/static/main.js

@@ -1,4 +1,4 @@
-getBookData = (isbn) => {
+function getBookData(isbn) {
     var table = document.getElementById("books-table");
     
     // Find all rows in the table except the header
@@ -32,7 +32,7 @@ getBookData = (isbn) => {
     return null;
 }
 
-function edit_book(isbn) {
+function openEditBookDialog(isbn) {
     var bookData = getBookData(isbn);
     if (bookData) {
         var editDialog = document.getElementById("edit-book-dialog");
@@ -55,7 +55,7 @@ function hideEditBookDialog() {
 }
 
 // Function to show the delete-book dialog
-function delete_book(isbn) {
+function openDeleteBookDialog(isbn) {
     var bookData = getBookData(isbn);
     console.log(isbn, bookData)
     if (bookData === null)

isbn_sort/templates/base.html

@@ -11,7 +11,6 @@
   <link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}">
 </head>
 <body>
-  <script src="{{ url_for('static', filename='main.js') }}" defer></script>
   <div id="container">
     {% for message in get_flashed_messages() %}
     <div class="flash">{{ message }}</div>

isbn_sort/templates/index.html

@@ -7,6 +7,8 @@
 {% endblock %}
 
 {% block content %}
+<script src="{{ url_for('static', filename='main.js') }}" defer></script>
+<script src="{{ url_for('static', filename='dynamicUpdate.js') }}" defer></script>
 <dialog id="edit-book-dialog">
     <form id="edit-book-form" action="/app/update-book" method="post">
         <input type="hidden" id="edit-isbn" value="" name="isbn">
@@ -60,8 +62,8 @@
           <td><p {% if book.publisher == None %}class="red"{% endif %}>{{ book.publisher }}</p></td>
           <td><p {% if book.count != 1 %}class="red"{% endif %}>{{ book.count }}</p></td>
           <td>
-              <button class="action" onclick="edit_book({{ book.isbn }})">✏️</button>
-              <button class="action" onclick="delete_book({{ book.isbn }})">🗑️</button>
+              <button class="action" onclick="openEditBookDialog({{ book.isbn }})">✏️</button>
+              <button class="action" onclick="openDeleteBookDialog({{ book.isbn }})">🗑️</button>
           </td>
       </tr>
       {% endfor %}