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SQLAlchemy filter query for Hybrid Property Enum

I have these models in my FastApi Python project with SqlAlchemy:
class Status(Enum):
SUCCESS = "SUCCESS"
FAILURE = "FAILURE"
class BarModel(Base):
__tablename__ = "Bar"
id = Column(Integer, ForeignKey("foo.id"), primary_key=True)
name = Column(String, nullable=True)
class FooModel(Base):
__tablename__ = "foo"
id = Column(Integer, autoincrement=True, primary_key=True)
flag_one = Column(Boolean, nullable=True, default=None)
bar = relationship("BarModel", lazy="joined", uselist=False)
#hybrid_property
def hybrid_enum(self) -> Status:
if (
self.flag_one
and self.bar is not None
and self.bar.name is not None
):
return Status.SUCCESS
else:
return Status.FAILURE
My hybrid_enum property works like a charm when reading data from the database.
However, when i want to do a filter query based on the hybrid property:
db.query(FooModel)
.filter(FooModel.hybrid_enum == Status.SUCCESS)
.all(),
I receive the following error:
AttributeError: Neither 'InstrumentedAttribute' object nor
'Comparator' object associated with FooModel.bar has an
attribute 'name'
I also tried to join the BarModel, but it results in the same error. What am i missing here?

FastAPI model test importing errors

I try to write tests for my FastAPI application but I get some import errors.
I'm trying to do very simple testing for my models, e.g.:
models/example.py:
class ExampleDbModel(ExampleBase, table=True):
__tablename__ = "example"
id: str
name: str
relation_id: str = Field(foreign_key="another_example.id")
...
relation: AnotherExampleDbModel = Relationship()
class AnotherExampleDbModel(AnotherExampleBase, table=True):
__tablename__ = "another_example"
id: str
some_field: str
relation_id: str = Field(foreign_key="third_example.id")
...
relation: ThirdExampleDbModel = Relationship()
tests/test_example.py:
def test_example():
example = ExampleDbModel(name="test")
fields = [
"id",
"name",
...
]
class_fields = example.dict().keys()
diff = set(fields) ^ set(list(class_fields))
assert not diff
This gives me an error: sqlalchemy.exc.InvalidRequestError: Table 'third_example' is already defined for this MetaData instance. Specify 'extend_existing=True' to redefine options and columns on an existing Table object.. Am I right when assuming it's because the model AnotherExampleDbModel has its own fk relation to another table? How could I test a model that has relations to another table (which has relations to another table)?

ManyToMany with SQLalchemy in Fastapi

I have a following models with many-to-many relations:
dashboard_customer_association = Table(
"entry_customer",
Base.metadata,
Column("entry_id", ForeignKey("entry.id"), primary_key=True),
Column("customer_id", ForeignKey("customer.id"), primary_key=True),
)
class Customer(Base):
__tablename__ = "customer"
id = Column(Integer, primary_key=True, index=True, autoincrement=True)
name = Column(String(64), unique=True, index=True)
class Entry(Base):
__tablename__ = "entry"
id = Column(String(16), primary_key=True, index=True)
customer = relationship("Customer", secondary=dashboard_customer_association)
Here's my pydantic schema.
class Entry(BaseModel):
id: str
customer: List[str] = []
class Config:
orm_mode = True
I've managed to insert the data and create the customers alongside,
but the problem is when I'm trying to retrieve data:
pydantic.error_wrappers.ValidationError: 2 validation errors for Entry
response -> customer -> 0
str type expected (type=type_error.str)
response -> customer -> 1
str type expected (type=type_error.str)
I understand that the Customer object is not a string, so customer
field cannot be directly serialized as List[str], but I fail to see
how am I supposed to do the conversion.
I return the data with the following function:
def get_data(item_id):
instance = db.query(models.Entry).filter(models.Entry.id == item_id).first()
return instance
I was trying to set instance.customer = [customer.name for customer in instance.customer],
but SQLalchemy prevents that. What is the right way to do that?

The best way would be to simply match the schema to the returned data and have a Customer object as well.
However, if that is not an option, you can use a validator to change the content when it's being populated - i.e. just return a single value from your Customer object.
#validator('customer')
def customer_as_string(cls, v):
return v.name

Insert into temp table using SQLAlchemy

I want to create a temp table from a result of CTE using SQLAlchemy.
Tables definition:
class Data(Base):
__tablename__ = 'data'
c_id = Column(Integer, primary_key=True)
# ...
# temp table
class CIdTmp(Base):
__tablename__ = '#c_id_tmp'
c_id = Column(Integer, primary_key=True)
This is my CTE:
c_id_cte = (session.query(Data.c_id)).cte('c_id_cte')
I tried combining insert() with from_select() like this:
session.execute(CIdTmp.insert().from_select(['c_id'], c_id_cte))
But it produces this error:
AttributeError: type object 'CIdTmp' has no attribute 'insert'

Ok, I found out that I have to get a Table object to execute an insert expression. It can be done by using ___table__ on my model.
session.execute(CIdTmp.__table__.insert().from_select(['c_id'], c_id_cte))

Flask SQLAlchemy select child object - return JSONB column

I have a class with a one-many relationship. I would like to return all the parent’s children in the relationship ; specifically I’d like to return all the JSONB objects in my children tables.
These are my class:
class Parent(db.Model):
__tablename__ = ‘parent220416'
id = db.Column(db.Integer, primary_key=True)
children = db.relationship(‘Child’, backref=‘Parent’, lazy='dynamic')
class Child(db.Model):
__tablename__ = ‘child220416'
id = db.Column(db.Integer, primary_key=True)
parentid = db.Column(db.Integer, db.ForeignKey('words220416.id'))
data = db.Column(JSONB)
Then with Flask Restful, I’m trying to select all the child like this:
class ParentChild(Resource):
def get(self, id):
result = db.session.query(Parent).get(id)
result_child = result.children
return {'child': result_child}
There is an error:
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <sqlalchemy.orm.dynamic.AppenderBaseQuery object at 0x106178da0> is not JSON serializable

If you want to get all of the data objects for each Child of the Parent. you could do the following query:
result_child = db.session.query(Child.data).filter(Child.parentid == id).all()
If you want to use the children relationship, it is possible to iterate over it:
result_child = [child.data for child in result.children]