Python 炼金术+；SQLite非空故障

我有一个简单的注册表，它将插入我的SQLite数据库。但是它失败了，因为它显示

email

列与

notnull

约束相矛盾。即使来自

电子邮件的输入正在提交和识别

数据库模型（炼金术）：

class Registration(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    email = db.Column(db.String(50))
    username = db.Column(db.String(20))
    password = db.Column(db.String(350))

form = RegistrationForm()
    if request.method == "POST" and form.validate_on_submit():
        username = form.username.data
        email = form.email.data
        password = bcrypt.hashpw(form.password.data.encode('utf-8'), bcrypt.gensalt(14))

        # Query DB for existing username
        user = Registration.query.filter_by(username=username).first()
        # Query DB for existing email
        email = Registration.query.filter_by(email=email).first()

        # If username exits
        if user:
            flash("Sorry that username is already taken, please choose another!")
            return render_template('register.html', form=form)

        # If email exists
        elif email:
            flash('That email is already associated with another account, please use another!')
            return render_template('register.html', form=form)

        else:
            new_user = Registration(email=email, username=username, password=password)
            db.session.add(new_user)
            db.session.commit()
            flash("Thanks for registering, {u}!".format(u=username))

            return redirect(url_for('home'))

(sqlite3.IntegrityError) NOT NULL constraint failed: registration.email [SQL: 'INSERT INTO registration (email, username, password) VALUES (?, ?, ?)'] [parameters: (None, 'test_user', b'$2b$14$fiL14w35s.kckAY5timb9uE0d9pQ/K9RZpRuNPBlnsKl3FHaQfFoG')]

注册码：

class Registration(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    email = db.Column(db.String(50))
    username = db.Column(db.String(20))
    password = db.Column(db.String(350))

form = RegistrationForm()
    if request.method == "POST" and form.validate_on_submit():
        username = form.username.data
        email = form.email.data
        password = bcrypt.hashpw(form.password.data.encode('utf-8'), bcrypt.gensalt(14))

        # Query DB for existing username
        user = Registration.query.filter_by(username=username).first()
        # Query DB for existing email
        email = Registration.query.filter_by(email=email).first()

        # If username exits
        if user:
            flash("Sorry that username is already taken, please choose another!")
            return render_template('register.html', form=form)

        # If email exists
        elif email:
            flash('That email is already associated with another account, please use another!')
            return render_template('register.html', form=form)

        else:
            new_user = Registration(email=email, username=username, password=password)
            db.session.add(new_user)
            db.session.commit()
            flash("Thanks for registering, {u}!".format(u=username))

            return redirect(url_for('home'))

(sqlite3.IntegrityError) NOT NULL constraint failed: registration.email [SQL: 'INSERT INTO registration (email, username, password) VALUES (?, ?, ?)'] [parameters: (None, 'test_user', b'$2b$14$fiL14w35s.kckAY5timb9uE0d9pQ/K9RZpRuNPBlnsKl3FHaQfFoG')]

错误：

class Registration(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    email = db.Column(db.String(50))
    username = db.Column(db.String(20))
    password = db.Column(db.String(350))

form = RegistrationForm()
    if request.method == "POST" and form.validate_on_submit():
        username = form.username.data
        email = form.email.data
        password = bcrypt.hashpw(form.password.data.encode('utf-8'), bcrypt.gensalt(14))

        # Query DB for existing username
        user = Registration.query.filter_by(username=username).first()
        # Query DB for existing email
        email = Registration.query.filter_by(email=email).first()

        # If username exits
        if user:
            flash("Sorry that username is already taken, please choose another!")
            return render_template('register.html', form=form)

        # If email exists
        elif email:
            flash('That email is already associated with another account, please use another!')
            return render_template('register.html', form=form)

        else:
            new_user = Registration(email=email, username=username, password=password)
            db.session.add(new_user)
            db.session.commit()
            flash("Thanks for registering, {u}!".format(u=username))

            return redirect(url_for('home'))

(sqlite3.IntegrityError) NOT NULL constraint failed: registration.email [SQL: 'INSERT INTO registration (email, username, password) VALUES (?, ?, ?)'] [parameters: (None, 'test_user', b'$2b$14$fiL14w35s.kckAY5timb9uE0d9pQ/K9RZpRuNPBlnsKl3FHaQfFoG')]

但这表明找到了电子邮件地址：

2017-03-20 13:35:19,082 INFO sqlalchemy.engine.base.Engine ('insert@gmail.com', 1, 0)

但之后的两行是：

2017-03-20 13:35:19,084 INFO sqlalchemy.engine.base.Engine INSERT INTO registration (email, username, password) VALUES (?, ?, ?)
2017-03-20 13:35:19,084 INFO sqlalchemy.engine.base.Engine (None, 'test_user', b'$2b$14$fiL14w35s.kckAY5timb9uE0d9pQ/K9RZpRuNPBlnsKl3FHaQfFoG')

为什么它会尝试为
电子邮件插入
None
，即使它显示实际输入的电子邮件？
因为您运行此查询：

email=Registration.query.filter\u by（email=email.first（）

您正在使用该查询的结果覆盖您的
电子邮件
变量。如果没有找到匹配的条目，您将用
None
替换
email
，这将导致您的问题

同样有趣的是，我不明白为什么你的
email
列有
notnull
约束-你对该列的定义是：

email=db.Column（db.String（50））

它不会为列指定任何约束。如果要确保此列从不为NULL，应将其更改为：

email=db.Column（db.String（50），nullable=False）