Create new tickets based on existing tickets

Description

The NewTicketLikeThisPlugin adds a "Clone" button to existing tickets, which lets you create a new ticket whose fields derive from the original ticket if you have the appropriate permission.

It is based on the tracopt.ticket.clone.ticketclonebutton extension that ships with Trac core. Unlike that extension, the NewTicketLikeThisPlugin defines and consumes a pluggable interface for implementing custom policies to determine the way in which a new ticket is derived from the original. This allows flexible, customized business logic to be provided based on the needs and workflows of your team. Also, the NewTicketLikeThisPlugin allows you to configure the permission required to clone a ticket, whereas the core ticketclonebutton hard-codes the TICKET_ADMIN permission.

Two policies are provided by default, in the newticketlikethis.policies module:

• SimpleTicketCloner mimics the behavior of the core tracopt.ticket.clone.ticketclonebutton extension: all fields from the original ticket are cloned, and the "summary" and "description" fields are modified to denote the ticket that they were cloned from.
• DerivedFieldsTicketCloner can ignore certain fields entirely based on a configuration setting; can derive new field values from the old ticket using Genshi templates, also through configuration; and clones all remaining fields from the original ticket verbatim.

More complex policies might implement custom logic for deriving new ticket values based on the values of the existing ticket's fields, or use alternate cloning policies based on the ticket's type.

Configuration

To use the plugin, install it in your Trac environment and enable its components in trac.ini:

[components]
newticketlikethis.* = enabled

By default this will add the "Clone" button to the ticket view, and will use the SimpleTicketCloner component to clone your tickets. The TICKET_ADMIN permission will be required for cloning tickets.

Choosing a policy

To use a different ticket-cloning policy, make sure to enable any necessary components and then set the newticketlikethis.ticket_cloner option in trac.ini to reference the component's name like so:

[newticketlikethis]
ticket_cloner = ExcludedFieldsTicketCloner

Using an alternate form handler

By default the "Clone" button will submit a POST request to the current Trac environment's /newticket handler. You can specify an alternate form submission (such as a different Trac instance's /newticket handler) with:

[newticketlikethis]
ticket_clone_form_action = http://trac.example.com/main/newticket
ticket_clone_form_method = GET

Either or both of these options may be omitted.

Configuring permissions

By default the "Clone" button only appears if the user has the TICKET_ADMIN permission. You can change the required permission using the newticketlikethis.ticket_clone_permission option:

[newticketlikethis]
ticket_clone_permission = TICKET_CREATE

DerivedFieldsTicketCloner

If enabled, the DerivedFieldsTicketCloner will look for an additional configuration option newticketlikethis.excluded_fields to determine which fields to exclude. This should be a comma-separated list of ticket fields. By default, no fields are excluded.

It will also look for an option newticketlikethis.derived_fields to determine how to derive new field values from the existing ticket. This should be a comma-separated list of Genshi templates mapped to new field values.

For example, you might use a trac.ini configuration like:

[newticketlikethis]
ticket_cloner = DerivedFieldsTicketCloner
excluded_fields = description, summary, reporter
derived_fields = $ticket.reporter->cc, milestone:$ticket.milestone component:$ticket.component->keywords

This would allow you to create cloned tickets with the old ticket's reporter CCed; the old ticket's milestone and component namespaced and set as keywords on the new ticket; the new ticket's description, summary and reporter left blank; and all other fields from the old ticket transferred verbatim to the new ticket.

Customization

It is easy to implement your own custom policies as well. Look at the code in newticketlikethis.policies for inspiration.

If you implement a custom policy that you would like to share, feel free to submit it as a patch, so that the NewTicketLikeThisPlugin can ship with a strong library of reusable cloning policies.