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A package which allows Pyramid requests to join the active transaction

Project description Documentation Status

pyramid_tm is a package which allows Pyramid requests to join the active transaction as provided by the transaction package.

See or docs/index.rst in this distribution for detailed documentation.


2.4 (2020-01-06)

2.3 (2019-09-30)

2.2.1 (2018-10-23)

2.2 (2017-07-03)

Backward Incompatibilities

  • This is a backward-incompatible change for anyone using the tm.commit_veto hook. Anyone else is unaffected.

    The tm.commit_veto hook will now be consulted for any squashed exceptions instead of always aborting. Previously, if an exception was handled by an exception view, the transaction would always be aborted. Now, the commit_veto can inspect request.exception and the generated response to determine whether to commit or abort.

    The new behavior when using the pyramid_tm.default_commit_veto is that a squashed exception may be committed if either of the following conditions are true:

    • The response contains the x-tm header set to commit.

    • The response’s status code does not start with 4 or 5.

    In most cases the response would result in 4xx or 5xx exception and would be aborted - this behavior remains the same. However, if the squashed exception rendered a response that is 3xx or 2xx (such as raising pyramid.httpexceptions.HTTPFound), then the transaction will be committed instead of aborted.


2.1 (2017-06-07)

  • On Pyramid >= 1.7 any errors raised from pyramid_tm invoking and will be caught and used to lookup and execute an exception view to return an error response. This exception view will be executed with an inactive transaction manager. See

2.0 (2017-04-11)

Major Features

Backward Incompatibilities

  • The tm.attempts setting has been removed and retry support has been moved into a new package named pyramid_retry. If you want retry support then please look at that library for more information about installing and enabling it. See

  • The pyramid_tm tween has been moved over the EXCVIEW tween. If you have any hacks in your application that are opening a new transaction inside your exception views then it’s likely you will want to remove them or re-evaluate when upgrading. See

  • Drop support for Pyramid < 1.5.

Minor Features

  • Support for Python 3.6.

1.1.1 (2016-11-21)

1.1.0 (2016-11-19)

  • Support transaction 2.x.

  • The transaction’s request path and userid are now coerced to unicode by first decoding as utf-8 and falling back to latin-1. If the userid does not conform to these restrictions then set tm.annotate_user = no in your settings. See

1.0.2 (2016-11-18)

1.0.1 (2016-10-24)

  • Removes the AttributeError when is accessed outside the tween. It turns out this broke subrequests as well as pshell and pyramid.paster.bootstrapp CLI scripts, especially when using the global transaction manager which can be tracked outside of the tween. See

1.0 (2016-09-12)

  • Drop Python 2.6, 3.2 and 3.3 support.

  • Add Python 3.5 support.

  • Subtle bugs can occur if you use the transaction manager during a request in which pyramid_tm is disabled via an activate_hook. To combat these types of errors, attempting to access will now raise an AttributeError when pyramid_tm is inactive. See

0.12.1 (2015-11-25)

  • Fix compatibility with 1.2 and 1.3 again. This wasn’t fully fixed in the 0.12 release as the tween was relying on request properties working (which they do not inside tweens in older versions). See

0.12 (2015-05-20)

0.11 (2015-02-04)

0.10 (2015-01-06)

0.9 (2014-12-30)

0.8 (2014-11-12)

0.7 (2012-12-30)

  • Write unauthenticated userid and request.path_info as transaction metadata via t.setUser and t.note respectively during a commit.

0.6 (2012-12-26)

  • Disuse the confusing and bug-ridden generator-plus-context-manager “attempts” mechanism from the transaction package for retrying retryable exceptions (e.g. ZODB ConflictError). Use a simple while loop plus a counter and imperative logic instead.

0.5 (2012-06-26)

Bug Fixes

  • When a non-retryable exception was raised as the result of a call to transaction.manager.commit, the exception was not reraised properly. Symptom: an unrecoverable exception such as Unsupported: Storing blobs in <somestorage> is not supported. would be swallowed inappropriately.

0.4 (2012-03-28)

Bug Fixes


  • No longer tested under Python 2.5 by tox.ini (and therefore no longer tested under 2.5 by the Pylons Jenkins server). The package may still work under 2.5, but automated tests will no longer show breakage when it changes in ways that break 2.5 support.

  • Squash test deprecation warnings under Python 3.2.

0.3 (2011-09-27)


  • The transaction manager has been converted to a Pyramid 1.2 “tween” (instead of an event subscriber). It will be slotted directly “below” the exception view handler, meaning it will have a chance to handle exceptions before they are turned into responses. This means it’s best to “raise HTTPFound(…)” instead of “return HTTPFound(…)” if you want an HTTP exception to abort the transaction.

  • The transaction manager will now retry retryable exceptions (such as a ZODB conflict error) if tm.attempts is configured to be more than the default of 1. See the Retrying section of the documentation.

  • Python 3.2 compatibility (requires Pyramid 1.3dev+).

Backwards Incompatibilities

  • Incompatible with Pyramid < 1.2a1. Use pyramid_tm version 0.2 if you need compatibility with an older Pyramid installation.

  • The default_commit_veto commit veto callback is no longer configured into the system by default. Use tm.commit_veto = pyramid_tm.default_commit_veto in the deployment settings to add it. This is for parity with repoze.tm2, which doesn’t configure in a commit veto by default either.

  • The default_commit_veto no longer checks for the presence of the X-Tm-Abort header when attempting to figure out whether the transaction should be aborted (although it still checks for the X-Tm header). Use version 0.2 or a custom commit veto function if your application depends on the X-Tm-Abort header.

  • A commit veto is now called with two arguments: request and response. The request is the webob request that caused the transaction manager to become active. The response is the response returned by the Pyramid application. This call signature is incompatible with older versions. The call signature of a pyramid_tm 0.2 and older commit veto accepted three arguments: environ, status, and headers. If you’re using a custom commit_veto function, you’ll need to either convert your existing function to use the new calling convention or use a wrapper to make it compatible with the new calling convention. Here’s a simple wrapper function (bwcompat_commit_veto_wrapper) that will allow you to use your existing custom commit veto function:

    def bwcompat_commit_veto_wrapper(request, response):
        return my_custom_commit_veto(request.environ, response.status,


  • The pyramid_tm.commit_veto configuration setting is now canonically spelled as tm.commit_veto. The older spelling will continue to work, but may raise a deprecation error when used.

0.2 (2011-07-18)

  • A new header X-Tm is now honored by the default_commit_veto commit veto hook. If this header exists in the headerlist, its value must be a string. If its value is commit, the transaction will be committed regardless of the status code or the value of X-Tm-Abort. If the value of the X-Tm header is abort (or any other string value except commit), the transaction will be aborted, regardless of the status code or the value of X-Tm-Abort.

0.1 (2011-02-23)

  • Initial release, based on repoze.tm2

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