More common handler interface

pkg/common/handler_example.go

@@ -0,0 +1,97 @@
+package common
+
+// Example showing how to use the common handler interfaces
+// This file demonstrates the handler interface hierarchy and usage patterns
+
+// ProcessWithAnyHandler demonstrates using the base SpecHandler interface
+// which works with any handler type (resolvespec, restheadspec, or funcspec)
+func ProcessWithAnyHandler(handler SpecHandler) Database {
+	// All handlers expose GetDatabase() through the SpecHandler interface
+	return handler.GetDatabase()
+}
+
+// ProcessCRUDRequest demonstrates using the CRUDHandler interface
+// which works with resolvespec.Handler and restheadspec.Handler
+func ProcessCRUDRequest(handler CRUDHandler, w ResponseWriter, r Request, params map[string]string) {
+	// Both resolvespec and restheadspec handlers implement Handle()
+	handler.Handle(w, r, params)
+}
+
+// ProcessMetadataRequest demonstrates getting metadata from CRUD handlers
+func ProcessMetadataRequest(handler CRUDHandler, w ResponseWriter, r Request, params map[string]string) {
+	// Both resolvespec and restheadspec handlers implement HandleGet()
+	handler.HandleGet(w, r, params)
+}
+
+// Example usage patterns (not executable, just for documentation):
+/*
+// Example 1: Using with resolvespec.Handler
+func ExampleResolveSpec() {
+	db := // ... get database
+	registry := // ... get registry
+
+	handler := resolvespec.NewHandler(db, registry)
+
+	// Can be used as SpecHandler
+	var specHandler SpecHandler = handler
+	database := specHandler.GetDatabase()
+
+	// Can be used as CRUDHandler
+	var crudHandler CRUDHandler = handler
+	crudHandler.Handle(w, r, params)
+	crudHandler.HandleGet(w, r, params)
+}
+
+// Example 2: Using with restheadspec.Handler
+func ExampleRestHeadSpec() {
+	db := // ... get database
+	registry := // ... get registry
+
+	handler := restheadspec.NewHandler(db, registry)
+
+	// Can be used as SpecHandler
+	var specHandler SpecHandler = handler
+	database := specHandler.GetDatabase()
+
+	// Can be used as CRUDHandler
+	var crudHandler CRUDHandler = handler
+	crudHandler.Handle(w, r, params)
+	crudHandler.HandleGet(w, r, params)
+}
+
+// Example 3: Using with funcspec.Handler
+func ExampleFuncSpec() {
+	db := // ... get database
+
+	handler := funcspec.NewHandler(db)
+
+	// Can be used as SpecHandler
+	var specHandler SpecHandler = handler
+	database := specHandler.GetDatabase()
+
+	// Can be used as QueryHandler
+	var queryHandler QueryHandler = handler
+	// funcspec has different methods: SqlQueryList() and SqlQuery()
+	// which return HTTP handler functions
+}
+
+// Example 4: Polymorphic handler processing
+func ProcessHandlers(handlers []SpecHandler) {
+	for _, handler := range handlers {
+		// All handlers expose the database
+		db := handler.GetDatabase()
+
+		// Type switch for specific handler types
+		switch h := handler.(type) {
+		case CRUDHandler:
+			// This is resolvespec or restheadspec
+			// Can call Handle() and HandleGet()
+			_ = h
+		case QueryHandler:
+			// This is funcspec
+			// Can call SqlQueryList() and SqlQuery()
+			_ = h
+		}
+	}
+}
+*/