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
+		}
+	}
+}
+*/

pkg/common/interfaces.go

@@ -246,3 +246,39 @@ type PrimaryKeyNameProvider interface {
 type SchemaProvider interface {
 	SchemaName() string
 }
+
+// SpecHandler interface represents common functionality across all spec handlers
+// This is the base interface implemented by:
+//   - resolvespec.Handler: Handles CRUD operations via request body with explicit operation field
+//   - restheadspec.Handler: Handles CRUD operations via HTTP methods (GET/POST/PUT/DELETE)
+//   - funcspec.Handler: Handles custom SQL query execution with dynamic parameters
+//
+// The interface hierarchy is:
+//
+//	SpecHandler (base)
+//	├── CRUDHandler (resolvespec, restheadspec)
+//	└── QueryHandler (funcspec)
+type SpecHandler interface {
+	// GetDatabase returns the underlying database connection
+	GetDatabase() Database
+}
+
+// CRUDHandler interface for handlers that support CRUD operations
+// This is implemented by resolvespec.Handler and restheadspec.Handler
+type CRUDHandler interface {
+	SpecHandler
+
+	// Handle processes API requests through router-agnostic interface
+	Handle(w ResponseWriter, r Request, params map[string]string)
+
+	// HandleGet processes GET requests for metadata
+	HandleGet(w ResponseWriter, r Request, params map[string]string)
+}
+
+// QueryHandler interface for handlers that execute SQL queries
+// This is implemented by funcspec.Handler
+// Note: funcspec uses standard http.ResponseWriter and *http.Request instead of common interfaces
+type QueryHandler interface {
+	SpecHandler
+	// Methods are defined in funcspec package due to different function signature requirements
+}