Template Engine

Revel allows for building and using custom template engines; the process for building your own engine is as follows

Building a new Template Engine

A template engine must implement the TemplateEngine interface. To register a new engine in Revel :

• Define it as a module to be loaded in the app.conf.
• In the init() function of the engine, register the engine in revel by calling:
  RegisterTemplateLoader(key string, loader func(loader *TemplateLoader) (TemplateEngine, error)) (err error)
• Specify the template engines to be used by setting the template.engines configuration option to the names of the engine to be used (a comma delimited list).

Template Engine Interface

• Event(event int, arg interface{}) Called when a revel.TemplateRefresh or revel.TemplateRefreshComplete occurs. This allows the engine to do a pre-initialize, before the templates are loaded, and could also do some form of memory release once the templates are loaded.

• Handles(templateView *TemplateView) bool Called for every view found, revel creates a Trevel.TemplateView instance and calls every engine to see if they are the one to be used to parse the view

• ParseAndAdd(basePath *TemplateView) error Called on application startup, or when templates have been changed.

• Name() string Called to fetch the name of the template engine.

• Lookup(templateName string) revel.Template Called to fetch the template, see below for what the template interface implements.

There is a helper struct called revel.EngineHandles which can be used to examine the view to check to see if it contains a shebang or a file extenstion that matches the name of the engine , see revel.GoEngine for some examples

Template Interface

• Name() string Name of template
• Content() []string The content of the template as a string (Used in error handling).
• Render(wr io.Writer, context interface{}) error Called by the server to render the template out the io.Writer, context contains the view args to be passed to the template.
• Location() string // The full path to the file on the disk.

There is a helper struct called revel.TemplateView, which implements the Location function, see revel.GoEngine for some examples