feat: add path params; add pathparams example

context.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"maps"
 	"reflect"
 	"sync"
 	"time"
@@ -20,12 +21,13 @@ type Context struct {
 	route             string
 	app               *V
 	view              func() h.H
+	routeParams       map[string]string
 	componentRegistry map[string]*Context
 	parentPageCtx     *Context
 	patchChan         chan patch
 	actionRegistry    map[string]func()
 	signals           *sync.Map
-	mutex             sync.RWMutex
+	mu                sync.RWMutex
 	ctxDisposedChan   chan struct{}
 }
 
@@ -170,8 +172,8 @@ func (c *Context) Signal(v any) *signal {
 		changed: true,
 	}
 
-	c.mutex.Lock()
+	c.mu.Lock()
-	defer c.mutex.Unlock()
+	defer c.mu.Unlock()
 	if c.isComponent() { // components register signals on parent page
 		c.parentPageCtx.signals.Store(sigID, sig)
 	} else {
@@ -187,8 +189,8 @@ func (c *Context) injectSignals(sigs map[string]any) {
 		return
 	}
 
-	c.mutex.Lock()
+	c.mu.Lock()
-	defer c.mutex.Unlock()
+	defer c.mu.Unlock()
 
 	for sigID, val := range sigs {
 		if _, ok := c.signals.Load(sigID); !ok {
@@ -218,8 +220,8 @@ func (c *Context) getPatchChan() chan patch {
 }
 
 func (c *Context) prepareSignalsForPatch() map[string]any {
-	c.mutex.RLock()
+	c.mu.RLock()
-	defer c.mutex.RUnlock()
+	defer c.mu.RUnlock()
 	updatedSigs := make(map[string]any)
 	c.signals.Range(func(sigID, value any) bool {
 		if sig, ok := value.(*signal); ok {
@@ -322,6 +324,42 @@ func (c *Context) stopAllRoutines() {
 	}
 }
 
+func (c *Context) injectRouteParams(params map[string]string) {
+	if params == nil {
+		return
+	}
+	m := make(map[string]string)
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	maps.Copy(m, params)
+	c.routeParams = m
+
+}
+
+// GetPathParam retrieves the value from the page request URL for the given parameter name
+// or an empty string if not found.
+//
+// Example:
+//
+//	v.Page("/users/{user_id}", func(c *via.Context) {
+//
+//			userID := GetPathParam("user_id")
+//
+//			c.View(func() h.H {
+//					return h.Div(
+//							h.H1(h.Textf("User ID: %s", userID)),
+//					)
+//			})
+//	})
+func (c *Context) GetPathParam(param string) string {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	if p, ok := c.routeParams[param]; ok {
+		return p
+	}
+	return ""
+}
+
 func newContext(id string, route string, v *V) *Context {
 	if v == nil {
 		log.Fatal("create context failed: app pointer is nil")
@@ -330,6 +368,7 @@ func newContext(id string, route string, v *V) *Context {
 	return &Context{
 		id:                id,
 		route:             route,
+		routeParams:       make(map[string]string),
 		app:               v,
 		componentRegistry: make(map[string]*Context),
 		actionRegistry:    make(map[string]func()),

internal/examples/pathparams/main.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"strconv"
+
+	"github.com/go-via/via"
+	"github.com/go-via/via-plugin-picocss/picocss"
+	. "github.com/go-via/via/h"
+)
+
+func main() {
+	v := via.New()
+
+	v.Config(via.Options{
+		Plugins: []via.Plugin{picocss.Default},
+	})
+
+	v.Page("/counters/{counter_id}/{start_at_step}", func(c *via.Context) {
+
+		counterID := c.GetPathParam("counter_id")
+		startAtStep, _ := strconv.Atoi(c.GetPathParam("start_at_step"))
+
+		count := 0
+		step := c.Signal(startAtStep)
+
+		increment := c.Action(func() {
+			count += step.Int()
+			c.Sync()
+		})
+
+		c.View(func() H {
+			return Main(Class("container"),
+
+				Nav(
+					Ul(
+						Li(
+							Strong(Text("⚡Via Example")),
+						),
+					),
+					Ul(
+						Li(
+							Raw(`<svg xmlns="http://www.w3.org/2000/svg" height="18" width="24.25" viewBox="0 0 496 512" class="icon-github"><path d="M165.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6zm-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3zm44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9zM244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8zM97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1zm-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7zm32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1zm-11.4-14.7c-1.6 1-1.6 3.6 0 5.9 1.6 2.3 4.3 3.3 5.6 2.3 1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2z"></path></svg>`),
+							A(Class("contrast"),
+								Text(" GitHub"),
+								Href("https://github.com/go-via/via"),
+							),
+						),
+					),
+				),
+
+				Section(
+					Article(
+						H3(Text(counterID)),
+						Hr(),
+						H5(Textf("Count %d", count)),
+						H6(Text("Step "), step.Text()),
+						FieldSet(Role("group"),
+							Input(Type("number"), step.Bind()),
+							Button(Text("Increment"), increment.OnClick()),
+						),
+					),
+				),
+			)
+		})
+
+	})
+
+	v.Start()
+}

routine.go

@@ -46,7 +46,8 @@ func (r *OnIntervalRoutine) Stop() {
 	r.localInterrupt <- struct{}{}
 }
 
-func newOnIntervalRoutine(ctxDisposedChan chan struct{}, duration time.Duration, handler func()) *OnIntervalRoutine {
+func newOnIntervalRoutine(ctxDisposedChan chan struct{},
+	duration time.Duration, handler func()) *OnIntervalRoutine {
 	r := &OnIntervalRoutine{
 		ctxDisposed:    ctxDisposedChan,
 		localInterrupt: make(chan struct{}),

via.go

@@ -161,6 +161,8 @@ func (v *V) Page(route string, initContextFn func(c *Context)) {
 		}
 		id := fmt.Sprintf("%s_/%s", route, genRandID())
 		c := newContext(id, route, v)
+		routeParams := extractParams(route, r.URL.Path)
+		c.injectRouteParams(routeParams)
 		initContextFn(c)
 		v.registerCtx(c)
 		if v.cfg.DevMode {
@@ -484,3 +486,21 @@ func genRandID() string {
 	rand.Read(b)
 	return hex.EncodeToString(b)[:8]
 }
+
+func extractParams(pattern, path string) map[string]string {
+	p := strings.Split(strings.Trim(pattern, "/"), "/")
+	u := strings.Split(strings.Trim(path, "/"), "/")
+	if len(p) != len(u) {
+		return nil
+	}
+	params := make(map[string]string)
+	for i := range p {
+		if strings.HasPrefix(p[i], "{") && strings.HasSuffix(p[i], "}") {
+			key := p[i][1 : len(p[i])-1] // remove {}
+			params[key] = u[i]
+		} else if p[i] != u[i] {
+			continue
+		}
+	}
+	return params
+}