Version 10 (modified by Rob Guttman, 10 years ago) (diff)

added overwrite docs for copy_from rule

Dynamically hide, default, copy, clear, etc. ticket fields


This plugin dynamically changes fields in ticket views based on simple rules using JavaScript / jQuery (required for this plugin). Example dynamic behavior:

  • 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


  1. Install the plugin (after downloading and unzipping):
    cd dynamicfieldsplugin/0.11
    sudo python bdist_egg
    sudo cp dist/TracDynamicFields*.egg /your/trac/location/plugins/

See TracPlugins for more installation details and options. You'll likely need to restart Trac's web server after installation.

  1. Enable the plugin:
    dynfields.* = enabled

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

See the examples section below for how to specify rules.

Bugs/Feature Requests

Existing bugs and feature requests for DynamicFieldsPlugin are here.

If you have any issues, create a new ticket.


Download the zipped source from [download:dynamicfieldsplugin here].


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


This plugin currently includes four rules. Each rule is specified by modifying the [ticket-custom] section of trac.ini. Below are several examples to motivate using 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 = 

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

alwayshidden.show_when_type = invalid_value
alwayshidden.clear_on_hide = false

The clear_on_hide option above specifies that the field's value should not be cleared when hidden (clearing is the default behavior).

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

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
captain.overwrite = false

The default copy behavior is to not overwrite a value if one already exists or the target field is hidden. To always copy the value, set the overwrite option to true.

Default value 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)

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

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.

Extensibility (implementation details)

Rules are implemented as Trac extension points to allow for new rules to be added fairly easily. Four 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.

Recent Changes

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

Refs #13821.

17752 by rjollos on 2020-05-17 23:39:45
TracDynamicFields 2.5.0dev: Revise comments

Refs #13821.

17751 by rjollos on 2020-05-17 23:29:29
TracDynamicFields 2.5.0dev: Change layout only if fields reordered

Refs #13821.



Author: robguttman
Maintainer: robguttman