Add TilesViewResolver to enable fallback if tiles definition does not exist [SPR-5689]

[spring-projects-issues]

Mark Fisher opened SPR-5689 and commented

Currently the typical way of integrating Tiles is to use a TilesView as the 'viewClass' for a UrlBasedViewResolver. Any UrlBasedViewResolver instance will prevent later resolvers in a chain (those with a higher 'order' value) from being invoked at all, because UrlBasedViewResolvers do not return null. In this particular case, the TilesView will be created and returned even if it the 'url' is an invalid tiles definition name.

However, it should be possible to add an earlier check within a TilesViewResolver implementation since the TilesContainer does provide an isValidDefinition(..) method. That way, we could return null and enable fallback to additional ViewResolvers in the chain.

For one thing, this would allow incremental adoption of Tiles within a large application that is currently using JSP via InternalViewResolver (and JstlView).

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Issue Links:

• Make Tiles 2 easier to configure in Spring MVC [SPR-5406] #10079 Make Tiles 2 easier to configure in Spring MVC

2 votes, 2 watchers

[spring-projects-issues]

Dave Syer commented

For a FreemarkerView (and VelocityView) the same feature would be equally useful - if the template doesn't exist, we know that it isn't going to render, so it would be better to resolve to null.

[spring-projects-issues]

Dave Syer commented

Rossen suggested using the viewNames property of the UrlBasedViewResolver. This works up to a point, but isn't really very helpful for less simple use cases (I want to create my views once, and possibly in another JAR file than where the view resolver lives).

[spring-projects-issues]

Juergen Hoeller commented

I've added a general checkResource mechanism to AbstractUrlBasedView and UrlBasedViewResolver, which VelocityView, FreeMarkerView and TilesView support now. Without any special configuration, UrlBasedViewResolvers should return null if the target resource doesn't exist for those now. I've also added a convenience TilesViewResolver, which is just a UrlBasedViewResolver with TilesView as default view class.

However, this hasn't been integration-tested yet. Any volunteers? :-)

Juergen