[web2py] How to hang Rocket with Web2py 2.0.9, Postgres 9, pscopg2

[Cliff Kachinske]

System: Ubuntu 12.4 LTS, Web2py 2.0.9, Postgres 9, psycopg2

In the model, start with a table like this:

db.define_table('subject_revisions',
        Field('subject_id', 'reference subjects', 
            readable=False, writable=False,),
        Field('revision', length=32),
        Field('effective_date', 'date', requires=IS_EMPTY_OR(IS_DATE())),
        )

We are going to attempt to change revision to a required integer. 

First, comment it out so Postgres drops the column.
db.define_table('subject_revisions',
        Field('subject_id', 'reference subjects', 
            readable=False, writable=False,),
        # Field('revision', length=32),
        Field('effective_date', 'date', requires=IS_EMPTY_OR(IS_DATE())),
        )

Then put it back as an integer field.
b.define_table('subject_revisions',
        Field('subject_id', 'reference subjects', 
            readable=False, writable=False,),
        Field('revision', 'integer'),
        Field('effective_date', 'date', requires=IS_EMPTY_OR(IS_DATE())),
        )

Now using the admin interface, make sure that all entries in the table have 
an integer value in the field.

Make the field required.
b.define_table('subject_revisions',
        Field('subject_id', 'reference subjects', 
            readable=False, writable=False,),
        Field('revision', length=32, required=True),
        Field('effective_date', 'date', requires=IS_EMPTY_OR(IS_DATE())),
        )

So far so good.  Refresh the admin interface and observe no errors.

Now try to tell Postgres to not allow nulls.  Make this change to the field 
def:
        Field('revision', length=32, required=True, notnull=True),

Postgres chokes with this error:

IntegrityError: column "revision__tmp" contains null values


Remove the notnull constraint and attempt to refresh the admin interface.  
Rocket will hang at this point.



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