[sqlalchemy] Re: insertion of an object with a user defined field value
The id is generate by the database engine, not SQLAlchemy, so session.add()
does nothing to push your object to the database and generate the id. You
need to execute session.flush() after session.add() to write the book to the
database and generate the id. After the flush() operation, the book id is
available to save in your dictionary.
something like this:
bk_ids = {}
for title in ('Tom Sawyer', 'Huck Finn'):
book = Book(title=title)
session.add(book)
session.flush()
bk_ids[title] = book.id
session.commit()
Without the flush(), the id will be NULL.
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[sqlalchemy] Re: insertion of an object with a user defined field value
Thanks for the quick response. However, the problem I face is not
being able to access the id assigned by database but not being able to
modify the corresponding field in Page instance. To be more clear:
bk_ids = {}
for title in ('Tom Sawyer', 'Huck Finn'):
book = Book(title=title)
session.add(book)
session.flush()
bk_ids[title] = book.id
session.commit()
for i, content in enumerate(('Once upon a time there was a little
fellow called Tom.', 'His surname was Sawyer.')):
page = Page(i, content, bk_ids['Tom Sawyer'])
session.add(page)
session.commit()
When I check the database, book_id field in pages table is not
modified as it supposed (or at least I suppose) to be.
On Nov 9, 3:12 pm, Mike Conley mconl...@gmail.com wrote:
The id is generate by the database engine, not SQLAlchemy, so session.add()
does nothing to push your object to the database and generate the id. You
need to execute session.flush() after session.add() to write the book to the
database and generate the id. After the flush() operation, the book id is
available to save in your dictionary.
something like this:
bk_ids = {}
for title in ('Tom Sawyer', 'Huck Finn'):
book = Book(title=title)
session.add(book)
session.flush()
bk_ids[title] = book.id
session.commit()
Without the flush(), the id will be NULL.
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[sqlalchemy] Re: insertion of an object with a user defined field value
Using your class definitions, it seems to work. What is different?
Base.metadata.bind=create_engine('sqlite:///')
Base.metadata.create_all()
session=sessionmaker()()
bk_ids = {}
for title in ('Tom Sawyer', 'Huck Finn'):
book = Book(title=title)
session.add(book)
session.flush()
bk_ids[title] = book.id
session.commit()
print bk_ids
for i, content in enumerate((
'Once upon a time there was a little fellow called Tom.',
'His surname was Sawyer.')):
page = Page(i, content, bk_ids['Tom Sawyer'])
session.add(page)
session.commit()
for page in session.query(Page):
print 'page:',page.id,' book:',page.book_id
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[sqlalchemy] Re: insertion of an object with a user defined field value
It does indeed! It is my bad, it works as expected, the problem was
due to not flushing properly before storing the values in the
dictionary.
Sorry for the inconvenience and thank you for the support.
On Nov 9, 4:46 pm, Mike Conley mconl...@gmail.com wrote:
Using your class definitions, it seems to work. What is different?
Base.metadata.bind=create_engine('sqlite:///')
Base.metadata.create_all()
session=sessionmaker()()
bk_ids = {}
for title in ('Tom Sawyer', 'Huck Finn'):
book = Book(title=title)
session.add(book)
session.flush()
bk_ids[title] = book.id
session.commit()
print bk_ids
for i, content in enumerate((
'Once upon a time there was a little fellow called Tom.',
'His surname was Sawyer.')):
page = Page(i, content, bk_ids['Tom Sawyer'])
session.add(page)
session.commit()
for page in session.query(Page):
print 'page:',page.id,' book:',page.book_id
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