使用Flask-SqlAlchemy编辑Sqlite条目时遭遇ProgrammingError错误

编辑SQLite数据库条目提交时出现以下错误：

sqlalchemy.exc.ProgrammingError: (sqlite3.ProgrammingError) Error binding parameter 1: type 'StringField' is not supported
[SQL: UPDATE blog_post SET title=?, subtitle=?, body=?, author=?, img_url=? WHERE blog_post.id = ?]
[parameters: (<wtforms.fields.simple.StringField object at 0x0000020F99680610>, <wtforms.fields.simple.StringField object at 0x0000020F99680C10>, <flask_ckeditor.fields.CKEditorField object at 0x0000020F99682250>, <wtforms.fields.simple.StringField object at 0x0000020F99682ED0>, <wtforms.fields.simple.StringField object at 0x0000020F99682310>, 2)]

数据库表定义：

class BlogPost(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(250), unique=True, nullable=False)
    subtitle = db.Column(db.String(250), nullable=False)
    date = db.Column(db.String(250), nullable=False)
    body = db.Column(db.Text, nullable=False)
    author = db.Column(db.String(250), nullable=False)
    img_url = db.Column(db.String(250), nullable=False)

条目编辑代码：

@app.route("/edit/<int:post_id>", methods=["GET", "POST"])
def edit_post(post_id):
    with app.app_context():
        post = db.session.query(BlogPost).filter_by(id = post_id).first()
        print(post.__dict__)
        # post_data = CreatePostForm(obj=post)
        post_data = CreatePostForm(
                title = post.title,
                subtitle = post.subtitle,
                author = post.author,
                img_url = post.img_url,
                body = post.body
            )
        if post_data.validate_on_submit():
            print(post.title)
            post.title = post_data.title
            post.subtitle = post_data.subtitle
            post.author = post_data.author
            post.img_url = post_data.img_url
            post.body = post_data.body
            db.session.commit()

            return redirect(url_for('show_post', index = post_id))
        return render_template('make-post.html', form = post_data, is_edit = True)

错误根源是你直接将WTForms的字段对象（如post_data.title）赋值给了数据库模型字段，而非字段对应的实际输入值。WTForms字段必须通过.data属性才能获取用户提交的内容。

修改提交逻辑部分的代码，为每个字段添加.data：

if post_data.validate_on_submit():
    print(post.title)
    post.title = post_data.title.data
    post.subtitle = post_data.subtitle.data
    post.author = post_data.author.data
    post.img_url = post_data.img_url.data
    post.body = post_data.body.data
    db.session.commit()

    return redirect(url_for('show_post', index = post_id))

另外，初始化表单时推荐使用obj=post自动填充字段，比手动赋值更简洁不易出错：

# 替换原手动初始化代码
post_data = CreatePostForm(obj=post)

内容的提问来源于stack exchange，提问作者Daikyu