Flask 从sqlalchemy\mptt目录树中获取所有项目很热
我正在使用sqlalchemy\u mptt创建树结构。我的模型定义如下:Flask 从sqlalchemy\mptt目录树中获取所有项目很热,flask,sqlalchemy,Flask,Sqlalchemy,我正在使用sqlalchemy\u mptt创建树结构。我的模型定义如下: class TreeGroup(BaseNestedSets, db.Model): name = db.Column(db.String(400), index=True, unique=True) note = db.Column(db.Text(), nullable=True) items = db.relationship("Item", backref='item', lazy='dy
class TreeGroup(BaseNestedSets, db.Model):
name = db.Column(db.String(400), index=True, unique=True)
note = db.Column(db.Text(), nullable=True)
items = db.relationship("Item", backref='item', lazy='dynamic')
def __init__(self, name, parent_id=None):
self.uuid = uuid4().hex
self.name = name
self.parent_id = parent_id
def __repr__(self):
return '{}'.format(self.name)
class Item(db.Model):
__tablename__ = 'items'
id = db.Column(db.Integer, primary_key=True)
category_id = db.Column(db.Integer, db.ForeignKey('tree_groups.id'))
name = db.Column(db.String(475), index=True)
插入的虚拟数据:
db.session.add(TreeGroup(name="Root")) # root node
db.session.add_all( # second level
[
TreeGroup(name="Test2", parent_id=1), # id=2
TreeGroup(name="Test3", parent_id=1), # id=3
TreeGroup(name="Test4", parent_id=1), # id=4
]
)
db.session.add_all( # third level
[
TreeGroup(name="Test5", parent_id=2), # id=5
TreeGroup(name="Test6", parent_id=2), # id=6
TreeGroup(name="Test7", parent_id=3), # id=7
TreeGroup(name="Test8", parent_id=3), # id=8
TreeGroup(name="Test9", parent_id=4), # id=9
TreeGroup(name="Test10", parent_id=4) # id=10
]
)
db.session.add_all( # fourth level
[
TreeGroup(name="Test11", parent_id=5),
TreeGroup(name="Test12", parent_id=5),
TreeGroup(name="Test13", parent_id=6),
TreeGroup(name="Test14", parent_id=7)
]
)
db.session.commit()
现在让我们关注id=3的节点(“Test3节点”)。我想查看它的所有项目,以及他下面的项目。(来自子节点:Test7节点和Test8节点以及它们的子节点(Test7)->Test14
我怎样才能做到这一点?我想:
-递归的
-也许是一些棘手的炼金术
我还知道,可以通过以下方式获得儿童:
x = TreeGroup.query.filter_by(name=group_name).first()
children = x.drilldown_tree() #but will that help me?
您是对的-您可以使用
向下钻取\u tree()
+递归。以下是示例:
def print_tree(group_name, tab=1):
"""
:param str group_name:
:param int tab: used just for formatting
"""
group = TreeGroup.query.filter_by(name=group_name).one_or_none() # type: TreeGroup
if not group:
return
# group found - print name and find children
print('- ' * tab + group.name)
for child_group in group.children: # type: TreeGroup
# new tabulation value for child record
print_tree(child_group.name, tab * 2)
示例:
# print_tree('Test3')
- Test3
- - Test7
- - - - Test14
- - Test8
# print_tree('Test2')
- Test2
- - Test5
- - - - Test11
- - - - Test12
- - Test6
- - - - Test13
希望这有帮助。谢谢!真的很有帮助。