燒瓶SQLAlchemy的多對多插入

Question

Flask sqlalchemy many-to-many insert data

我已經試過了上述建議，但繼續插入一個新的職位與標籤時收到上許多的附加以下錯誤很多屬性。

任何方向將不勝感激！

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

11:06:22 PM web.1 | File "/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/collections.py", line 1072, in append

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

11:06:22 PM web.1 | File "/home/trevor/Projects/trevorblog/venv/local /lib/python2.7/site-packages/sqlalchemy/orm/collections.py", line 1044, in __set

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

11:06:22 PM web.1 | File "/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/collections.py", line 716, in fire_append_event

11:06:22 PM web.1 | item, initiator)

11:06:22 PM web.1 | File "/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 936, in fire_append_event

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

11:06:22 PM web.1 | File "/home/trevor/Projects/trevorblog/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 1171, in 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' object has no attribute '_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 

不返回Tag，但Query。你想Tag.query.filter(...).one_or_none()獲得標籤本身。