Added support for middleware functions (#5)

Author: aosasona

handle.go

@@ -13,6 +13,13 @@ import (
 
 // handleProcedureCall handles a procedure call, calling the procedure and returning the result from the handler
 func (r *Robin) handleProcedureCall(ctx *Context, procedure Procedure) error {
+	// Call the procedure middleware functions before we proceed to to any work
+	for _, middleware := range procedure.MiddlewareFns() {
+		if err := middleware(ctx); err != nil {
+			return err
+		}
+	}
+
 	var (
 		data = struct {
 			Payload any `json:"d"`

mutation.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"go.trulyao.dev/robin/internal/guarded"
+	"go.trulyao.dev/robin/types"
 )
 
 type (
@@ -24,6 +25,9 @@ type (
 		// WARNING: This never really has a value, it's just used for "type inference/reflection" during runtime
 		out ReturnType
 
+		// Middleware functions to be executed before the mutation is called
+		middlewareFns []types.Middleware
+
 		// Whether the mutation expects a payload or not
 		expectsPayload bool
 	}
@@ -88,6 +92,17 @@ func (m *mutation[_, _]) Validate() error {
 	return nil
 }
 
+// MiddlewareFns returns the middleware functions that should be executed before the mutation is called
+func (m *mutation[_, _]) MiddlewareFns() []types.Middleware {
+	return m.middlewareFns
+}
+
+// WithMiddleware sets the middleware functions for the mutation
+func (m *mutation[_, _]) WithMiddleware(fns ...types.Middleware) Procedure {
+	m.middlewareFns = append(m.middlewareFns, fns...)
+	return m
+}
+
 // Creates a new mutation with the given name and handler function
 func Mutation[R any, B any](name string, fn MutationFn[R, B]) *mutation[R, B] {
 	var body B

query.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"go.trulyao.dev/robin/internal/guarded"
+	"go.trulyao.dev/robin/types"
 )
 
 type (
@@ -24,6 +25,9 @@ type (
 		// WARNING: This never really has a value, it's just used for "type inference/reflection" during runtime
 		out ReturnType
 
+		// Middleware functions to be executed before the mutation is called
+		middlewareFns []types.Middleware
+
 		// Whether the query expects a payload or not
 		expectsPayload bool
 	}
@@ -88,6 +92,17 @@ func (q *query[_, _]) Validate() error {
 	return nil
 }
 
+// MiddlewareFns returns the middleware functions to be executed before the query is called
+func (q *query[_, _]) MiddlewareFns() []types.Middleware {
+	return q.middlewareFns
+}
+
+// Add the middleware functions for the query
+func (q *query[_, _]) WithMiddleware(fns ...types.Middleware) Procedure {
+	q.middlewareFns = append(q.middlewareFns, fns...)
+	return q
+}
+
 // Creates a new query with the given name and handler function
 func Query[R any, B any](name string, fn QueryFn[R, B]) *query[R, B] {
 	var body B

types/procedure.go

@@ -41,8 +41,16 @@ type Procedure interface {
 
 	// Validate the procedure
 	Validate() error
+
+	// Middleware to be executed before the procedure is called
+	MiddlewareFns() []Middleware
+
+	// Set the middleware functions for the procedure
+	WithMiddleware(...Middleware) Procedure
 }
 
+type Middleware func(*Context) error
+
 // No-op type to represent a procedure that doesn't return any response or take any payload
 type (
 	_RobinVoid struct{} // Used for identification of robin's special void type