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https://issues.apache.org/jira/browse/WW-5768?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Lukasz Lenart resolved WW-5768.
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Resolution: Fixed
> Make struts.ui.theme and struts.ui.templateDir scopable per package
> -------------------------------------------------------------------
>
> Key: WW-5768
> URL: https://issues.apache.org/jira/browse/WW-5768
> Project: Struts 2
> Issue Type: Improvement
> Components: Core Tags
> Reporter: Lukasz Lenart
> Priority: Major
> Fix For: 7.5.0
>
> Time Spent: 1h
> Remaining Estimate: 0h
>
> The first adopter of package-scoped constants
> ([WW-3476|https://issues.apache.org/jira/browse/WW-3476]). That change
> shipped the mechanism only, and no constant is scopable yet, so any
> {{<scoped-constant>}} currently fails at startup.
> h2. Goal
> Allow a package to override the default UI theme and template directory:
> {code:xml}<package name="admin" extends="struts-default" namespace="/admin">
> <scoped-constant name="struts.ui.theme" value="css_xhtml"/>
> <scoped-constant name="struts.ui.templateDir" value="admin-template"/>
> ...
> </package>
> {code}
> Child packages inherit the override through {{extends}}. Today the same
> effect needs a {{theme}} attribute on every tag, or an interceptor that puts
> {{theme}} into the request scope.
> h2. Why these two constants
> {{UIBean.getTheme()}} and {{UIBean.getTemplateDir()}} resolve their values
> when a tag renders, inside the result, so the action invocation and its
> package are known. The injected global value is only the last step of an
> existing chain:
> # the tag attribute
> # the enclosing form (theme only)
> # the request / session / application {{theme}} / {{templateDir}} attribute
> # the injected {{defaultUITheme}} / {{defaultTemplateDir}}
> Only step 4 changes. Everything users rely on today keeps its precedence.
> h2. Proposed change
> * Register a {{ScopableConstants}} bean in {{struts-beans.xml}} (for example
> {{StrutsUiScopableConstants}}) that returns {{struts.ui.theme}} and
> {{struts.ui.templateDir}}.
> * Inject {{ScopedConstantProvider}} into {{UIBean}}, and in step 4 use
> {{scopedConstantProvider.getValue(...)}} instead of the injected field. The
> provider already falls back to the global constant when there is no
> invocation (a JSP rendered without an action) or no override.
> * Register the bean in {{StrutsDefaultConfigurationProvider}} too, for the
> test harness.
> h2. Tests
> * A package override is used when the tag has no {{theme}} / {{templateDir}}.
> * The tag attribute, the enclosing form's theme, and a request-scope
> {{theme}} attribute still win over the override.
> * A child package inherits the parent's override.
> * With no invocation, or no override, the global constant is used.
> * The previously rejected {{<scoped-constant name="struts.ui.theme">}} now
> loads, and an unrelated name is still rejected at startup.
> h2. Docs
> Update the struts-site page for scoped constants
> ({{package-configuration.md}}, see struts-site PR #351) to list these two as
> the scopable constants, and mention the override in the themes and templates
> page.
> h2. Out of scope
> * {{struts.ui.theme.expansion.token}} and {{struts.ui.staticContentPath}}
> * {{struts.convention.result.path}}: it is read at startup by
> {{DefaultResultMapBuilder}}, when there is no invocation, so it needs a
> lookup by package name. That is a separate ticket.
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