Question

Flask sqlalchemy many-to-many insert data

我已经尝试了上述建议，但在插入带有标签的新帖子时，继续收到多个属性追加的以下错误。

任何方向都会非常感激！

1:06:22 PM web.1 |的 post.tags.append（post_tag）

11:06:22 PM web.1 |文件“/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/collections.py”，第1072行，附后

11:06:22 PM web.1 | item = __set（self，item，_sa_initiator）

11:06:22 PM web.1 |在__set中输入文件“/ home / trevor / Projects / trevorblog / venv / local /lib/python2.7/site-packages/sqlalchemy/orm/collections.py”，第1044行

11:06:22 PM web.1 | item = executor.fire_append_event（item，_sa_initiator）

11:06:22 PM web.1 |在fire_append_event中输入文件“/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/collections.py”，第716行

11:06:22 PM web.1 |项目，发起人）

11:06:22 PM web.1 |在fire_append_event中输入文件“/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py”，第936行

11:06:22 PM web.1 | initiator或self._append_token或self._init_append_token（））

11:06:22 PM web.1 |文件“/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py”，第1171行，在emit_backref_from_collection_append_event

11:06:22 PM web.1 | child_state，child_dict = instance_state（child），\

11:06:22 PM web.1 | AttributeError：'BaseQuery'对象没有属性'_sa_instance_state'

Model.py

blog_tag = db.Table('post_tag',
db.Column('post_id', db.Integer, db.ForeignKey('post.id')),
db.Column('tag_id', db.Integer, db.ForeignKey('tag.id'))
)

class Post(db.Model):
    """SQLAlchemy Post object class"""
    id = db.Column(db.Integer, primary_key=True)
    body = db.Column(db.Text)
    timestamp = db.Column(db.DateTime)    
    title = db.Column(db.String(50))
    author = db.Column(db.Integer, db.ForeignKey('user.id'))
    uuid = db.Column(db.String(255))
    tags = db.relationship('Tag',secondary=blog_tag, 
                        back_populates="posts")

class Tag(db.Model):
    """SQLAlchemy Tag object class"""
    id=db.Column(db.Integer, primary_key=True)
    name=db.Column(db.String, unique=True, nullable=False)
    posts = db.relationship('Post', secondary = blog_tag,
                            back_populates = "tags")

Views.py

@console.route('/new_post', methods=['GET', 'POST'])
@login_required
def new_post():
    post_form = PostForm()
    if post_form.validate_on_submit():
        """Take the list of tags and turn them into an array"""
       uid = uuid.uuid4()
       post = Post()
       post.title = post_form.title.data
       post.body = post_form.body.data
       post.timestamp = datetime.utcnow()
       post.author = current_user.id
       post.uuid = uid.hex
       tag_string = post_form.tags.data
       tags = tag_string.split(",")
       for tag in tags:
           post_tag = add_tags(tag)
           print post_tag
           post.tags.append(post_tag)
       db.session.add(post)
       db.session.commit()
       flash (u'New Post Created!', 'alert-info')
    return render_template('new_post.html',
                title='Admin-New Post',
                form=post_form)

def add_tags(tag):
    existing_tag = Tag.query.filter(Tag.name == tag.lower())
    """if it does return existing tag objec to list"""
    if existing_tag is not None:
        return existing_tag
    else:
       new_tag = Tag()
       new_tag.name = tag.lower()
       return new_tag

Answer 1

此：

existing_tag = Tag.query.filter(Tag.name == tag.lower())
"""if it does return existing tag objec to list"""
if existing_tag is not None:
    return existing_tag

不会返回Tag，而是返回Query。您希望Tag.query.filter(...).one_or_none()获取标记本身。

Flask-SQLAlchemy多对多插入

1 个答案: