For Private page, add feature 'take note'

This makes this app much more meaningful. For this feature, a new database table is added. More complicated logics are also needed, for example, we use hash(user ID + timestamp + note contant) as the unique id of each note (it's necessary when we try to delete a note)

app.py

@@ -1,5 +1,6 @@
 from flask import Flask, session, url_for, redirect, render_template, request, abort, flash
 from database import list_users, verify, delete_user_from_db, add_user
+from database import read_note_from_db, write_note_into_db, delete_note_from_db, match_user_id_with_note_id
 
 app = Flask(__name__)
 app.config.from_object('config')
@@ -10,6 +11,10 @@ app.config.from_object('config')
 def FUN_401(error):
     return render_template("page_401.html"), 401
 
+@app.errorhandler(403)
+def FUN_403(error):
+    return render_template("page_403.html"), 403
+
 @app.errorhandler(404)
 def FUN_404(error):
     return render_template("page_404.html"), 404
@@ -33,7 +38,12 @@ def FUN_public():
 @app.route("/private/")
 def FUN_private():
     if "current_user" in session.keys():
-        return render_template("private_page.html")
+        notes_list = read_note_from_db(session['current_user'])
+        notes_table = zip([x[0] for x in notes_list],\
+                          [x[1] for x in notes_list],\
+                          [x[2] for x in notes_list],\
+                          ["/delete_note/" + x[0] for x in notes_list])
+        return render_template("private_page.html", notes = notes_table)
     else:
         return abort(401)
 
@@ -53,6 +63,26 @@ def FUN_admin():
 
 
 
+@app.route("/write_note", methods = ["POST"])
+def FUN_write_note():
+    text_to_write = request.form.get("text_note_to_take")
+    write_note_into_db(session['current_user'], text_to_write)
+
+    return(redirect(url_for("FUN_private")))
+
+@app.route("/delete_note/<note_id>", methods = ["GET"])
+def FUN_delete_note(note_id):
+    if session.get("current_user", None) == match_user_id_with_note_id(note_id): # Ensure the current user is NOT operating on other users' note.
+        delete_note_from_db(note_id)
+    else:
+        return abort(401)
+
+    return(redirect(url_for("FUN_private")))
+
+
+
+
+
 @app.route("/login", methods = ["POST"])
 def FUN_login():
     id_submitted = request.form.get("id").upper()

database.py

@@ -1,10 +1,12 @@
 import sqlite3
 import hashlib
+import datetime
 
-db_file_location = "database_file/users.db"
+user_db_file_location = "database_file/users.db"
+note_db_file_location = "database_file/notes.db"
 
 def list_users():
-    _conn = sqlite3.connect(db_file_location)
+    _conn = sqlite3.connect(user_db_file_location)
     _c = _conn.cursor()
 
     _c.execute("select id from users;")
@@ -15,7 +17,7 @@ def list_users():
     return result
 
 def verify(id, pw):
-    _conn = sqlite3.connect(db_file_location)
+    _conn = sqlite3.connect(user_db_file_location)
     _c = _conn.cursor()
 
     _c.execute("select pw from users where id = '" + id + "';")
@@ -26,20 +28,75 @@ def verify(id, pw):
     return result
 
 def delete_user_from_db(id):
-    _conn = sqlite3.connect(db_file_location)
+    _conn = sqlite3.connect(user_db_file_location)
     _c = _conn.cursor()
-
     _c.execute("delete from users where id = '" + id + "';")
+    _conn.commit()
+    _conn.close()
 
+    # when we delete a user from database USERS, we also need to delete all his or her notes data from database NOTES
+    _conn = sqlite3.connect(note_db_file_location)
+    _c = _conn.cursor()
+    _c.execute("delete from notes where user = '" + id + "';")
     _conn.commit()
     _conn.close()
 
 def add_user(id, pw):
-    _conn = sqlite3.connect(db_file_location)
+    _conn = sqlite3.connect(user_db_file_location)
     _c = _conn.cursor()
 
     command = "insert into users values('" + id.upper() + "', '" + hashlib.sha256(pw).hexdigest() + "');" 
     _c.execute(command)
+    
+    _conn.commit()
+    _conn.close()
+
+def read_note_from_db(id):
+    _conn = sqlite3.connect(note_db_file_location)
+    _c = _conn.cursor()
+
+    command = "select note_id, timestamp, note from notes where user = '" + id.upper() + "';" 
+    _c.execute(command)
+    result = _c.fetchall()
+
+    _conn.commit()
+    _conn.close()
+
+    return result
+
+def match_user_id_with_note_id(note_id):
+    # Given the note id, confirm if the current user is the owner of the note which is being operated.
+    _conn = sqlite3.connect(note_db_file_location)
+    _c = _conn.cursor()
+
+    command = "select user from notes where note_id = '" + note_id + "';" 
+    _c.execute(command)
+    result = _c.fetchone()[0]
+
+    _conn.commit()
+    _conn.close()
+
+    return result
+
+def write_note_into_db(id, note_to_write):
+    _conn = sqlite3.connect(note_db_file_location)
+    _c = _conn.cursor()
+
+    current_timestamp = str(datetime.datetime.now()) 
+    command = "insert into notes values('" + id.upper() + "', '" + \
+                current_timestamp + "', '" + note_to_write + \
+                "', '" + hashlib.sha1(id.upper() + current_timestamp + note_to_write).hexdigest() + "');" 
+    _c.execute(command)
+
+    _conn.commit()
+    _conn.close()
+
+def delete_note_from_db(note_id):
+    _conn = sqlite3.connect(note_db_file_location)
+    _c = _conn.cursor()
+
+    command = "delete from notes where note_id = '" + note_id + "';" 
+    _c.execute(command)
 
     _conn.commit()
     _conn.close()
@@ -47,5 +104,7 @@ def add_user(id, pw):
 
 
 
+
+
 if __name__ == "__main__":
     print list_users()

templates/admin.html

@@ -5,16 +5,18 @@
     
     {# only invoked when failed adding new ID due to duplication #}
     {% if id_to_add_is_duplicated %}
-      <div class="text-danger">
-        <strong>Warning!</strong> The account name already exists.
-      </div>
+    <div class="alert alert-dismissible alert-danger">
+      <button type="button" class="close" data-dismiss="alert">&times;</button>
+      <strong>Warning!</strong> The account name already exists.
+    </div>
     {% endif %}
     
     {# only invoked when failed adding new ID due to invalid character #}
     {% if id_to_add_is_invalid %}
-      <div class="text-danger">
-        <strong>Warning!</strong> The account name is invalid.
-      </div>
+    <div class="alert alert-dismissible alert-danger">
+      <button type="button" class="close" data-dismiss="alert">&times;</button>
+      <strong>Warning!</strong> The account name is invalid.
+    </div>
     {% endif %}
 
     <div class = "container">
@@ -63,10 +65,4 @@
     </div>
 
 
-
-
-
-    
-
-
 {% endblock %}

templates/page_403.html

@@ -0,0 +1,6 @@
+{% extends "layout.html" %}
+{% block page_title %}Forbidden(403){% endblock %}
+{% block body %}
+    {{ super() }}
+    This operation is forbidden.
+{% endblock %}

templates/private_page.html

@@ -2,6 +2,44 @@
 {% block page_title %}Private Page{% endblock %}
 {% block body %}
     {{ super() }}
-    <img src="{{ url_for('static', filename='img/private.jpg') }}" class="img-circle" alt="Cinque Terre" width="304" height="236">
-    Only logged-in users, like you, can access this page.
+
+    <h4>You can take notes here. Only yourself can access them. They will be removed when your account is removed.</h4>
+
+    <hr>
+    
+    <div class="form-group">
+      <label for="textArea" class="col-lg-3 control-label">Note to Take</label>
+      <div class="col-lg-9">
+      <form action="/write_note" method="post">
+        <input class="form-control" name="text_note_to_take"></input>
+        <button type="submit" class="btn btn-success">Submit</button>
+        </form>
+      </div>
+    </div>
+
+    <hr>
+
+    {% if notes %}
+        <h2>Your Notes</h2>
+        <table class="table">
+            <thead>
+                <tr>
+                  <th>Note ID</th>
+                  <th>Timestamp</th>
+                  <th>Note</th>
+                  <th>Action</th>
+                </tr>
+            </thead>
+            {% for note_id, timestamp, note, act in notes %}
+                    <tr>
+                       <td> {{ note_id }} </td>
+                       <td> {{ timestamp }} </td>
+                       <td> {{ note }} </td>
+                       <td><a href={{act}}>Delete</a></td>
+                    </tr>
+                    
+            {% endfor %}
+        </table>
+    {% endif %}
+
 {% endblock %}