Dynamically hide, default, copy, clear, validate, set ticket fields


This plugin dynamically changes fields in ticket views based on simple rules.

Key features:

  • Hide a field based on another field's value.
  • Default a field's value per user preference.
  • Clear a field's value when another field's value changes.
  • Copy one field's value to another field.
  • Validate a field's value.
  • Set a field's value based on another field's value.

In the configuration section a few worked out examples of how to use this plugin are presented.

This plugin requires JavaScript to be enabled.

Bugs/Feature Requests

Existing bugs and feature requests for DynamicFieldsPlugin are here.

If you have any issues, create a new ticket.


59 / 62


17 / 27


5 / 5


Download the zipped source from here.

The plugin is also available on PyPi.


You can check out DynamicFieldsPlugin from here using Subversion, or browse the source with Trac.

Install from the trunk when running Trac 1.0 and later.


  1. Install the plugin by one of the following methods:
    1. From PyPI using pip:
      $ pip install TracDynamicFields
    2. After downloading and unzipping:
      $ cd dynamicfieldsplugin/trunk
      $ python bdist_egg
      $ cp dist/TracDynamicFields*.egg /your/trac/location/plugins/
      See TracPlugins for more installation details and options. You will likely need to restart Trac's web server after installation.
  2. Enable the plugin:
    dynfields.* = enabled

You can alternatively use the Trac Web Admin GUI to enable any or all rules.


This plugin currently includes 6 rules. Each rule is specified by modifying the [ticket-custom] section of your trac.ini file. Below are several examples to each rule.

Hide rule

Let's say that your team only specifies effort for enhancements, but not for defects or other ticket types. This rule shows a custom effort field only when the type field's value is enhancement:

effort.show_when_type = enhancement

If effort is specified for either enhancement or defect ticket types, then use pipe-delimited syntax to list both of them:

effort.show_when_type = enhancement|defect

If your version field is based upon the milestone, then this rule hides the version field when the milestone field's value is empty:

version.hide_when_milestone = 

You may also hide fields based on group membership. For example, if only members of the production team should see a custom duedate field:

duedate.show_if_group = production

Some of your fields may be auto-generated or used by very few people. To always hide a field:

alwayshidden.hide_always = true
alwayshidden.clear_on_hide = false

Fields that are always hidden will also be hidden on the custom query (/query) page. The clear_on_hide option above specifies that the field's value should not be cleared when hidden (clearing is the default behavior). Sometimes you want to allow users to get access to hidden fields. You can enable specific fields to be shown in ticket views when a user clicks a "Show hidden fields" link:

mostlyhidden.show_when_type = enhancement
mostlyhidden.link_to_show = true

The default is that hidden fields are not enabled to be shown, ie link_to_show defaults to false. The "Show hidden fields" link is only shown when there are hidden fields and at least one of them is enabled to be shown.

Clear rule

In the version/milestone example above, if the milestone changes then we want the version field to be cleared:

version.clear_on_change_of = milestone

Note that 'clearing' a select field will actually reset it to its default value if no 'empty' option is available.

Copy rule

Let's say your workflow includes reassigning a ticket's owner to someone else for review or verification but maintain the person responsible for the work in a custom captain field. Initially the captain should be set to the owner, so to reduce data entry in making this so:

captain.copy_from = owner

The default copy behavior is to not overwrite a value if one already exists. To always copy the value, add (overwrite) as follows:

captain.copy_from = owner (overwrite)

Default rule

Let's say your QA team usually creates defect tickets and your product managers usually create enhancement tickets. Here's how to allow each user to set the default value for the ticket type:

type.default_value = (pref)

For text fields, if the field's value is not empty, the default value will not be applied unless you set an append option to true:

cc.default_value = (pref)
cc.append = true

Using append presumes the field is a comma-delimited list and will append any missing values from the default preference value (which can also be a comma-delimited list) to that field's list.

The above example introduces the plugin's user preference facility described below.

Validate rule

Some fields may be required, ie can't be empty, or must not contain some specific values. For example:

owner.invalid_if =
severity.invalid_if = pick one

The above will prevent the ticket from being submitted if either the owner field is empty or the severity field's value equals pick one. The value for the invalid_if rule can be empty or any regular expression. Hidden fields do not get validated.

You can also specify a condition under which the validation should be applied:

phase.invalid_if.1 = verifying
phase.invalid_when.1 = .codereviewstatus .pending (msg:Pending code reviews.)
phase.invalid_if.2 = verifying
phase.invalid_when.2 = .codereviewstatus:last .rejected (msg:The last code review did not pass.)

The above example is for the CodeReviewer plugin when using its ticket reference macro to prevent a ticket moving a custom phase field past "codereview" if there are either pending reviews or the last changeset has not passed review. The value is a jQuery selector and if it returns one or more items then the validation is applied, else it's skipped. The .1 and .2 suffix for the option keys are to group the invalid_if and invalid_when parts together.

Set rule

When a developer starts working on a ticket, you may want to make sure (s)he sets the milestone accordingly:

milestone.set_to_milestone3_when_phase = implementation|verifying|releasing

When the phase field changes to either implementation, verifying, or releasing, then the milestone will get set to milestone3. To avoid needing to update the current milestone's value in the rule, you can alternatively use the special "!" value which specifies to set the field to the first non-empty value:

milestone.set_to_!_when_phase = implementation|verifying|releasing

Toggling checkboxes is supported (as of version 1.2.6):

checkbox.set_to_true_when_component = component2 (overwrite)

If you want to enable each user to set the value as a preference, you set to a question mark ? as follows:

milestone.set_to_?_when_phase = implementation|verifying|releasing (pref)

Learn more about user preferences below. The default set behavior is to not overwrite a value if one already exists. To always set the value, add (overwrite) as follows:

milestone.set_to_!_when_phase = implementation|verifying|releasing (overwrite) (pref)

An (overwrite) must precede a (pref) as shown above.

User preferences

Any rule expressed above can be configured to allow users to set preferences for them by appending (pref) to the end of the rule. For example, here's one of the hide rules from above:

alwayshidden.show_when_type = invalid_value (pref)

The (pref) will cause this rule to be added to a new Dynamic Fields preference panel where the user can disable the rule by unchecking the rule's checkbox. Some rules require user input such as the default value rule above. In that example, the user can both enable/disable the rule as well as set the field's default value for him/her. If you wish to disable a rule as the default preference, append (pref:disable) to the end of the rule like so:

alwayshidden.show_when_type = invalid_value (pref:disable)


  • status cannot be used in rules (#8400)

Extensibility (implementation details)

Rules are implemented as Trac extension points to allow for new rules to be added fairly easily. Six rules come packaged to provide the dynamic behaviors described above. Each rule is split between two parts:

  1. rule specification (Python in
  2. rule implementation (JavaScript in rules.js)

The two parts are linked by instantiating the JavaScript part with the class name of the python part. See the code for details. JavaScript was chosen over Genshi transforms to dynamically have fields change without requiring a form submission - hence the plugin's name, Dynamic Fields.

About i18n/l10n support

The 0.12 branch of this plugin is prepared for localization.
But English message texts are still the (POSIX) default. If this isn't your preferred language, you can

  1. check if it's already available from the Trac plugin l10n project at Transifex or
  2. do it yourself: see the l10n cookbook page for Trac plugins for more details.

Contributing your translation is highly appreciated!

You could send it to the plugin's maintainer or contribute to Trac plugin l10n project via Transifex:

Top translations for dynfields:

Preparing the plugin from source now requires the additional step of compiling message catalog files. As long as you stick to the message catalogs served with this plugin directly, there is still nothing special to be done. Just package your plugin from source the standard way:

$ cd dynamicfieldsplugin
$ python bdist_egg

and the proper helper function calls to a suitable Babel install will be issued automatically for you. Beware, there is a Trac ticket strongly suggesting to do Babel install before Trac 0.12 install, or your Babel will not be functional with Trac. You're hit by this bug, if your message compilation does not produce any usable catalog.

Only if you encounter message catalogs with translations marked 'fuzzy', including them would require special treatment, since automatic compilation trashes them by default. Walk through:

$ cd dynamicfieldsplugin
$ python compile_catalog -f
$ python bdist_egg

Again, this is almost obsolete, and only needed to include translations marked as #, fuzzy by the translator. For more details see the l10n cookbook page for Trac plugins.

Recent Changes

17871 by rjollos on 2020-11-12 18:54:39
2.6.0dev: Fix textarea layout with Trac 1.0.x

Refs #8971.

17855 by rjollos on 2020-08-21 23:18:37
2.6.0dev: Add prefs template for Trac 1.4+

Refs #13875.

17755 by rjollos on 2020-05-18 13:56:57
2.6.0dev: Increment version after release

Refs #13821.



Author: robguttman
Maintainer: Ryan J Ollos
Contributors: hasienda

Last modified 2 years ago Last modified on May 31, 2022, 9:40:15 AM