How to define a table without primary key with SQLAlchemy?

Question

I have a table that does not have a primary key. And I really do not want to apply this constraint to this table.

In SQLAlchemy, I defined the

Answer 1

There is only one way that I know of to circumvent the primary key constraint in SQL Alchemy - it's to map specific column or columns to your table as a primary keys, even if they aren't primary key themselves. http://docs.sqlalchemy.org/en/latest/faq/ormconfiguration.html#how-do-i-map-a-table-that-has-no-primary-key.

Answer 2

The solution I found is to add an auto-incrementing primary key column to the table, then use that as your primary key. The database should deal with everything else beyond that.

Answer 3

There is no proper solution for this but there are workarounds for it:

Workaround 1

Adding parameter primary_key to the existing column that is not having a primary key will work.

class SomeTable(Base):
    __table__ = 'some_table'
    some_other_already_existing_column = Column(..., primary_key=True) # just add primary key to it whether or not this column is having primary key or not

Workaround 2

Just declare a new dummy column on the ORM layer, not in actual DB. Just define in SQLalchemy model

class SomeTable(Base):
    __table__ = 'some_table'
    column_not_exist_in_db = Column(Integer, primary_key=True) # just add for sake of this error, dont add in db

Answer 4

Disclaimer: Oracle only

Oracle databases secretly store something called rowid to uniquely define each record in a table, even if the table doesn't have a primary key. I solved my lack of primary key problem (which I did not cause!) by constructing my ORM object like:

class MyTable(Base)
    __tablename__ = 'stupid_poorly_designed_table'
    
    rowid = Column(String, primary_key=True)
    column_a = Column(String)
    column_b = Column(String)
    ...

You can see what rowid actually looks like (it's a hex value I believe) by running

SELECT rowid FROM stupid_poorly_designed_table
GO