Flask ImportError: cannot import name

Question

Hi I would like to import a model within a model. But It seems that I can't do it if both model are importing one another. To make it clear below is a sample code

# Files located in models with filename model_b.py
from repository.base_model import BaseModel
from models.model_a import ModelA

class ModelB(BaseModel):
     # properties and classes here
     # There's a join function here that make use of ModelA

Now I have another file which is named model_a that have a class of ModelA. I need to import ModelB as I need to do a join query.

# Files located in models with filename model_a.py
from repository.base_model import BaseModel
from models.model_b import ModelB

class ModelA(BaseModel):
     # properties and classes here
    def join_function(code, session):

      result = (session.query(ModelA).
                select_from(ModelA).
                join(ModelB, ModelB.id == ModelA.model_b_id).
                filter(ModelB.code == code).
                all())

If I run my script it say

ImportError: cannot import name 'ModelB'

Now if I remove the import of ModelB it works just fine. It seems that there is an issue when two Model are importing one another. Is there a solution to this?

[Python circular importing](https://stackoverflow.com/questions/22187279/python-circular-importing) — Sohaib Farooqi, Nov 11 '17 at 16:07
@GarbageCollector yeah that's what I figured out. But is there a way to accomplish this? ModelB really needs to make a join at ModelA and same with ModelA — MadzQuestioning, Nov 11 '17 at 16:08
[This answer](https://stackoverflow.com/a/43505554/5741172) describes circular one-to-one relations on both parent and child entities. I am not sure if it is applicable to your case. — Sohaib Farooqi, Nov 11 '17 at 16:16

Flask ImportError: cannot import name

0 Answers0