Changing the id field type , when I have not manually specified in the table, fails in migrations

[sumitsharansatsangi]

Earlier I have table as follows:

class Band(Table):
    name = Varchar(length=100)

When I am changing it to following , migration is giving the error that id already exists.

class Band(Table):
    id = UUID(primary_key=True)
    name = Varchar(length=100)

The problem is piccolo is considering the id field as it is newly added.
In the migration file , piccolo is generating the migration for add_column instead of alter_column

One way to solve this problem is that if the table already exist and the column which is added is a primary key then it should generate the migration of alter_column, because piccolo auto generates only the id column as primary key , if it is not manually specified in the table.

Above suggested way will work in the following condition too( Where a different name is specified for the primary key), with a modification which is that piccolo has to generate migration for rename_column too, ( for now without asking a question Did you rename the column in the table .... till piccolo doesn't support for complex primary key and specifying a complex primary key is not like as follows

class Band(Table):
    band_id = UUID(primary_key=True)
    name = Varchar(length=100)
    type = ForeignKey(references = BandType ,primary_key=True)

)

Before:

class Band(Table):
    name = Varchar(length=100)

After:

class Band(Table):
    band_id = UUID(primary_key=True)
    name = Varchar(length=100)

[dantownsend]

Yeah, it's tricky for Piccolo to change the primary key of a table, because it would also have to update any foreign keys pointing to the table.

I agree we could do something better though.

If the table has no data, one solution is to drop the table (just comment it out, and create a new migration). Then re-add it with the correct foreign key.

[sumitsharansatsangi]

Yeah, I have done the same. You are right, Updating Foreign key may be problematic.
We have to look into the implementation of some mature orm.