transaction.is_dirty() is very (and surprisingly) conservative

[Michael Hudson-Doyle]

As near as I can tell transaction.is_dirty() returns True if any queries have been executed at all (I think this is what lead to #15317 being reported). This is sort of fair enough (it's better to have a false positive for this sort of thing) but it certainly confused me for a good few minutes (commit_manually was complaining at me on exit). If it can't be made more accurate, at least the docstring should be improved. I'll try to come up with a patch tomorrow.

[Aymeric Augustin]

We're discussing ​https://docs.djangoproject.com/en/dev/topics/db/transactions/. I'm accepting this ticket as a documentation patch, to fix the following inconsistency.

The docs for commit_manually() say:

If your view changes data and doesn't commit() or rollback(), Django will raise a TransactionManagementError exception.

This is incompatible with the next paragraph, "Requirements for transaction handling":

This applies to all database operations, not just write operations. Even if your transaction only reads from the database, the transaction must be committed or rolled back before you complete a request.

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Also, I think this is related to #6623: that ticket discusses the wording of the error message, and your confusion certainly stemmed from there too.

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In terms of process, please assign the ticket to yourself if you're working on a patch.

[EmilStenstrom]

I find no occurrences of the string "Django will raise a TransactionManagementError exception" in the Django code base. Is the commit_manually docstring still misleading?

def commit_manually(using=None):
    """
    Decorator that activates manual transaction control. It just disables
    automatic transaction control and doesn't do any commit/rollback of its
    own -- it's up to the user to call the commit and rollback functions
    themselves.
    """
    ...

I suggest this bug is marked as resolved.

[Andreas Pelme]

This is the fix that is already committed:

​https://github.com/django/django/commit/620e0bba4969f27230d35f75bc6a1624c3fac747