How to use Pickle Type

[RamDurgaSai]

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Example Code

from sqlmodel import SQLModel, Field, PickleType



class FlowInDb(SQLModel, table=True):
    id : str = Field(primary_key=True)
    flow: PickleType
    
    class Config:
        arbitrary_types_allowed = True

Description

Getting Error ...
sqlalchemy.exc.CompileError: (in table 'flowindb', column 'flow'): Can't generate DDL for NullType(); did you forget to specify a type on this Column?

Operating System

Windows

Operating System Details

No response

SQLModel Version

0.06

Python Version

3.10

Additional Context

No response

[byrman]

Try flow: PickleType = Field(sa_column=Column(PickleType)).

[RamDurgaSai]

Try flow: PickleType = Field(sa_column=Column(PickleType)).

Thanks

Gettting ...

sqlalchemy.exc.IntegrityError: (sqlite3.IntegrityError) NOT NULL constraint failed: flowindb.flow
[SQL: INSERT INTO flowindb (flow, id) VALUES (?, ?)]
[parameters: (None, 'd4pgyYaU3nVCJgXjYu6b')]
(Background on this error at: https://sqlalche.me/e/14/gkpj)

[byrman]

My previous answer was perhaps a bit confusing. Suppose flow is of type Foo, then your code becomes:

class Foo:
    pass


class FlowInDb(SQLModel, table=True):
    id : str = Field(primary_key=True)
    flow: Foo = Field(sa_column=Column(PickleType))
    
    class Config:
        arbitrary_types_allowed = True

Then you can insert a FlowInDb instance into the database like this:

session.add(FlowInDb(id="d4pgyYaU3nVCJgXjYu6b", flow=Foo())
session.commit()

You don't have to pickle yourself, PickleType takes care of that.

[YuriiMotov]

Runnable code example:

from pydantic import ConfigDict
from sqlmodel import Column, Field, PickleType, Session, SQLModel, create_engine

class Foo:
    def __init__(self, a: str):
        self.a = a

class FlowInDb(SQLModel, table=True):
    model_config = ConfigDict(arbitrary_types_allowed=True)
    id : str = Field(primary_key=True)
    flow: Foo = Field(sa_column=Column(PickleType))

def main():
    engine = create_engine("sqlite:///", echo=True)
    SQLModel.metadata.create_all(engine)

    with Session(engine) as session:
        flow = FlowInDb(flow=Foo(a="asd"))
        session.add(flow)
        session.commit()

    with Session(engine) as session:
        flow_db = session.get(FlowInDb, 1)
        assert isinstance(flow_db.flow, Foo)
        assert flow_db.flow.a == "asd"