This is beautiful and exactly what I want. Thanks very much.
pjjH
On Mar 7, 12:08 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> On Mar 6, 2009, at 10:37 PM, phrrn...@googlemail.com wrote:
>
>
>
>
>
> > I have some metadata on table and some of the columns and would like
> > to surface these as docstrings on the mapped class and columns.
>
> > If table foo has columns i, j, k with comments 'apple', 'banana',
> > 'pear', respectively, and the table is mapped via class Foo then I
> > would like the programmer to do a help(Foo) and see something like:
>
> > i()
> > apple
>
> > j()
> > banana
>
> > k()
> > pear
>
> > or whatever the common Python idiom is. I am looking for something
> > that will work well for interactive work with ipython. In our case,
> > the comments are MS_Description properties from the
> > sys.extended_properties table in SQL Server. I searched through the
> > list archives and see that there has already been some discussion
> > about providing support for comments in the DDL producerers. Although
> > I am more interested in the mapper side of things, I can see how
> > sp_addextendedproperty, sp_updateextendedproperty could be used to
> > set the comments as part of the DDL generation.
>
> > Since I am code-generating all the alchemy models right now, it seems
> > reasonable to poke in the comment into the docstring of the class and
> > the the __doc__ attribute column properties after the mapper()
> > invocation. Or should one use some magic Python hook to get the value
> > of the docstring from elsewhere? For reference, I append the a
> > fragment of the code that retrieves the table and column
> > MS_Description properties that are widely used by a number of SQL
> > Server tools.
>
> reflection of column notes can be added, im not sure if any dialects
> support that currently. the plumbing to propagate that from info
> column to instrumented descriptor could be done using an
> InstrumentationManager, which allows you to receive events as
> descriptors are placed on classes.
>
> from sqlalchemy import *
> from sqlalchemy.orm import *
> from sqlalchemy.ext.declarative import declarative_base
> from sqlalchemy.orm import attributes, interfaces, properties
>
> Base = declarative_base()
>
> class AttachNotesAsDocstring(interfaces.InstrumentationManager):
> def instrument_attribute(self, class_, key, attr):
> if isinstance(attr.property, properties.ColumnProperty):
> attr.__doc__ = attr.property.columns[0].info.get('notes')
>
> attributes.instrumentation_finders.insert(0, lambda cls:
> AttachNotesAsDocstring)
>
> class User(Base):
> __tablename__ = "users"
>
> id = Column(Integer, primary_key=True, info={'notes':'the primary
> key'})
> name = Column(String, info={'notes':'the name'})
>
> help(User)
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