Python Flask和HTML：注销期间两个按钮之间的交互

我正在使用Flask设计我的博客，我注意到代码的不同行为取决于使用标签

或

如果我将标签

用于“发送”按钮和

为什么只有在使用HTML按钮类型时才会发生这种情况？为什么它与“发送”一个交互

from datetime import datetime
import flask_login
import yaml
import pdb
from flask import Flask, render_template, request, redirect, url_for 
from flask_login import LoginManager, UserMixin, login_required, logout_user
from flask_sqlalchemy import SQLAlchemy



app = Flask(__name__)
app.config['TESTING'] = False
app.config['SECRET_KEY'] = 'chiavesegreta'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////Users/franc/OneDrive/Desktop/Blog_Project/blog2.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

login_manager = LoginManager()
login_manager.init_app(app)


# {"Franz":{"pw":"Biberkopf"}}

with open(r'C://Users//franc//OneDrive//Desktop//application.yaml') as file:
    users = yaml.full_load(file)


class User(UserMixin):
    pass


class Blogpost2(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(50))
    subtitle = db.Column(db.String(50))
    author = db.Column(db.String(20))
    date_posted = db.Column(db.DateTime)
    content = db.Column(db.Text)


db.create_all()  


@app.route('/')
def index():
    posts = Blogpost2.query.order_by(Blogpost2.date_posted.desc()).all()

    return render_template('index.html', posts=posts)


@app.route('/about')
def about():
    return render_template('about.html')


@app.route('/post/<int:post_id>')
def post(post_id):
    post = Blogpost2.query.filter_by(id=post_id).one()  # .filter_by() ritrova tutti i post nel db filtrati per id

    date_posted = post.date_posted.strftime('%d %B, %Y')

    return render_template('post.html', post=post, date_posted=date_posted)


@login_manager.user_loader
def user_loader(username):
    if username not in users:
        return

    user = User()
    user.id = username
    return user


@login_manager.request_loader
def request_loader(request):
    username = request.form.get("username")  # comunica col template <input ...name = "username"> Username </input>
    if username not in users:
        return
    user = User()
    user.id = username
    user.is_authenticated = request.form["pw"] == users[username]["pw"]

    return user


@app.route('/login', methods=["POST", "GET"])
def login():
    error = None
    try: 
     if request.method == 'POST':
        username = request.form.get('username')
        if request.form.get('pw') == users[username]["pw"]:
            user = User()
            user.id = username
            flask_login.login_user(user)
            return redirect(url_for("add"))
    except KeyError:
        error = "Leider haben Sie die falschen Zugangsdaten."
        return render_template("login.html", error=error)
    return render_template("login.html")


@app.route('/add')
@login_required
def add():
    return render_template('add.html')


@app.route('/logout')
def logout():
    logout_user()
    return redirect(url_for('index'))


@app.route('/contact')
def contact():
    return render_template('contact.html')


@app.route('/prova')
def prova():
    return render_template('prova.html')


@app.route('/addpost', methods=['POST'])
def addpost():
    title = request.form['title']
    subtitle = request.form['subtitle']
    author = request.form["author"]
    content = request.form['content']

    post = Blogpost2(title=title, subtitle=subtitle, author=author, content=content, date_posted=datetime.now())

    db.session.add(post)
    db.session.commit()

    return redirect(url_for('index'))


if __name__ == "__main__":
    app.run(debug=True)




<!-- Main Content -->
  <div class="container">
    <div class="row">
      <div class="col-lg-8 col-md-10 mx-auto">
        <form name="addForm" id="addForm" method = "POST" action= "{{ url_for('addpost') }}" novalidate>
          <div class="control-group">
            <div class="form-group floating-label-form-group controls">
              <label>Title</label>
              <input type="text" class="form-control" placeholder="Title" name = "title" id="title" required data-validation-required-message="Dai un titolo al tuo post">
              <p class="help-block text-danger"></p>
            </div>
          </div>
          <div class="control-group">
            <div class="form-group floating-label-form-group controls">
              <label>Subtitle</label>
              <input type="text" class="form-control" placeholder="Subtitle" name = "subtitle" id="subtitle" required data-validation-required-message="Please enter your email address.">
              <p class="help-block text-danger"></p>
            </div>
          </div>
          <div class="control-group">
            <div class="form-group col-xs-12 floating-label-form-group controls">
              <label>Author</label>
              <input type="text" class="form-control" placeholder="Author" name = "author" id="author" required data-validation-required-message="Please enter your phone number.">
              <p class="help-block text-danger"></p>
            </div>
          </div>
          <div class="control-group">
            <div class="form-group floating-label-form-group controls">
              <label>Blog Content</label>
              <textarea rows="5" class="form-control" placeholder="Blog content" name = "content" id="content" required data-validation-required-message="Please enter a message."></textarea>
              <p class="help-block text-danger"></p>
            </div>
          </div>
          <br>
          <div id="success"></div>
          <button type="submit" class="btn btn-primary" id="sendMessageButton">Send</button>
          <a href = "{{ url_for('logout') }}" class="btn btn-primary" style="float: right;">Logout</a>
        </form> 
      </div>
    </div>
  </div>