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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Calculated columns not working (`sqlaquemy.orm.column_property`)","articleBody":"### First Check\r\n\r\n- [X] I added a very descriptive title to this issue.\r\n- [X] I used the GitHub search to find a similar issue and didn't find it.\r\n- [X] I searched the SQLModel documentation, with the integrated search.\r\n- [X] I already searched in Google \"How to X in SQLModel\" and didn't find any information.\r\n- [X] I already read and followed all the tutorial in the docs and didn't find an answer.\r\n- [X] I already checked if it is not related to SQLModel but to [Pydantic](https://github.com/samuelcolvin/pydantic).\r\n- [X] I already checked if it is not related to SQLModel but to [SQLAlchemy](https://github.com/sqlalchemy/sqlalchemy).\r\n\r\n### Commit to Help\r\n\r\n- [X] I commit to help with one of those options 👆\r\n\r\n### Example Code\r\n\r\n```python\r\nfrom typing import List\r\n\r\nfrom sqlalchemy import func\r\nfrom sqlalchemy import select as sa_select\r\nfrom sqlalchemy.orm import column_property\r\nfrom sqlmodel import create_engine, Field, Relationship, SQLModel\r\n\r\n\r\nclass Hero(SQLModel, table=True):\r\n    name: str = Field(primary_key=True)\r\n    team_name: str = Field(foreign_key=\"team.name\")\r\n    team: \"Team\" = Relationship(back_populates=\"heroes\")\r\n\r\n\r\nclass Team(SQLModel, table=True):\r\n    name: str = Field(primary_key=True)\r\n    heroes_count = column_property(\r\n        sa_select(func.count(Hero.team_name))\r\n        .where(Hero.team_name == name)\r\n        .correlate_except(Hero)\r\n        .scalar_subquery()\r\n    )\r\n    heroes: List[\"Hero\"] = Relationship(back_populates=\"team\")\r\n\r\n\r\nif __name__ == \"__main__\":\r\n    engine = create_engine(\"sqlite:///test.db\")\r\n    SQLModel.metadata.create_all(engine)\r\n```\r\n\r\n\r\n### Description\r\n\r\n* Create a Hero model\r\n* Crate a Team model\r\n* Create a calculated column using `sqlalquemy.orm.column_property` (https://docs.sqlalchemy.org/en/14/orm/mapped_sql_expr.html#using-column-property)\r\n* Create all tables and it will raise the `sqlalquemy.exc.InvalidRequestError`\r\n```shell\r\nsqlalchemy.exc.InvalidRequestError: When initializing mapper mapped class Hero-\u003ehero, expression 'Team' failed to locate a name ('Team').\r\nIf this is a class name, consider adding this relationship() to the \u003cclass '__main__.Hero'\u003e class after both dependent classes have been defined.\r\n```\r\n\r\n### Operating System\r\n\r\nmacOS\r\n\r\n### Operating System Details\r\n\r\n_No response_\r\n\r\n### SQLModel Version\r\n\r\n0.0.6\r\n\r\n### Python Version\r\n\r\nPython 3.9.6\r\n\r\n### Additional Context\r\n\r\n_No response_","author":{"url":"https://github.com/angel-langdon","@type":"Person","name":"angel-langdon"},"datePublished":"2022-02-09T12:10:11.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/240/sqlmodel/issues/240"}