sqlalchemy - Alembic default value to be used in add_column -
how alembic use specified default value new column, without making server_default
?
only existing rows should receive default value. new rows inserted after should still server_default
.
i had similar problem, wanted new column not nullable, not work existing rows, of course. created row without not null constraint first, filled column custom python code , altered column (in same migration) have constraint.
so you'd iterate on existing objects, set values according transient default.
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