fix: check for panics on page registration. Fix header append bug: was appending multiple ctx_id to the header; feat: handle complex signal init values as json; add tests; other small improvemnts

context.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"reflect"
 	"sync"
 
 	"github.com/go-via/via/h"
@@ -32,8 +33,7 @@ type Context struct {
 // Changes to signals or state can be pushed live with Sync().
 func (c *Context) View(f func() h.H) {
 	if f == nil {
-		c.app.logErr(c, "failed to bind view to context: nil func")
-		return
+		panic("nil viewfn")
 	}
 	c.view = func() h.H { return h.Div(h.ID(c.id), f()) }
 }
@@ -143,6 +143,12 @@ func (c *Context) Signal(v any) *signal {
 			err: fmt.Errorf("context '%s' failed to bind signal '%s': nil signal value", c.id, sigID),
 		}
 	}
+	switch reflect.TypeOf(v).Kind() {
+	case reflect.Slice, reflect.Struct:
+		if j, err := json.Marshal(v); err == nil {
+			v = string(j)
+		}
+	}
 	sig := &signal{
 		id:      sigID,
 		val:     v,
@@ -251,13 +257,13 @@ func (c *Context) Sync() {
 // Then, the merge will only occur if the ID of the top level element in the patch
 // matches 'my-element'.
 func (c *Context) SyncElements(elem h.H) {
-	patchChan := c.getPatchChan()
-	if c.view == nil {
-		c.app.logErr(c, "sync element failed: viewfn is nil")
+	if elem == nil {
+		c.app.logErr(c, "sync elements failed: view func is nil")
 		return
 	}
-	if elem == nil {
-		c.app.logErr(c, "sync element failed: view func is nil")
+	patchChan := c.getPatchChan()
+	if patchChan == nil {
+		c.app.logWarn(c, "sync elements failed: no sse stream")
 		return
 	}
 	b := bytes.NewBuffer(make([]byte, 0))
@@ -302,15 +308,15 @@ func (c *Context) ExecScript(s string) {
 	patchChan <- patch{patchTypeScript, s}
 }
 
-func newContext(id string, route string, app *V) *Context {
-	if app == nil {
-		log.Fatalf("create context failed: app pointer is nil")
+func newContext(id string, route string, v *V) *Context {
+	if v == nil {
+		log.Fatal("create context failed: app pointer is nil")
 	}
 
 	return &Context{
 		id:                id,
 		route:             route,
-		app:               app,
+		app:               v,
 		componentRegistry: make(map[string]*Context),
 		actionRegistry:    make(map[string]func()),
 		signals:           new(sync.Map),

go.mod

@@ -19,7 +19,7 @@ require (
 	github.com/kr/pretty v0.1.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	golang.org/x/sys v0.13.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -42,8 +42,8 @@ github.com/valyala/gozstd v1.20.1 h1:xPnnnvjmaDDitMFfDxmQ4vpx0+3CdTg2o3lALvXTU/g
 github.com/valyala/gozstd v1.20.1/go.mod h1:y5Ew47GLlP37EkTB+B4s7r6A5rdaeB7ftbl9zoYiIPQ=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
-golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
-golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
+golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

signal_test.go

@@ -0,0 +1,64 @@
+package via
+
+import (
+	//	"net/http/httptest"
+	"testing"
+
+	"github.com/go-via/via/h"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSignalReturnAsString(t *testing.T) {
+	testcases := []struct {
+		given    any
+		expected string
+	}{
+		{"test", "test"},
+		{"another", "another"},
+		{1, "1"},
+		{-99, "-99"},
+		{1.1, "1.1"},
+		{-34.345, "-34.345"},
+		{true, "true"},
+		{false, "false"},
+	}
+
+	for _, testcase := range testcases {
+		var sig *signal
+		v := New()
+		v.Page("/", func(c *Context) {
+			c.View(func() h.H { return nil })
+			sig = c.Signal(testcase.given)
+		})
+
+		assert.Equal(t, testcase.expected, sig.String())
+
+	}
+}
+
+func TestSignalReturnAsStringComplexTypes(t *testing.T) {
+	testcases := []struct {
+		given    any
+		expected string
+	}{
+		{[]string{"test"}, `["test"]`},
+		{[]int{1, 2}, "[1, 2]"},
+		{struct{ Val string }{"test"}, `{"Val": "test"}`},
+		{struct {
+			Num        int
+			IsPositive bool
+		}{1, true}, `{"Num": 1, "IsPositive": true}`},
+	}
+
+	for _, testcase := range testcases {
+		var sig *signal
+		v := New()
+		v.Page("/", func(c *Context) {
+			c.View(func() h.H { return nil })
+			sig = c.Signal(testcase.given)
+		})
+
+		assert.JSONEq(t, testcase.expected, sig.String())
+
+	}
+}

via.go

@@ -18,6 +18,7 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/go-via/via/h"
 	"github.com/starfederation/datastar-go/datastar"
@@ -38,6 +39,10 @@ type V struct {
 	devModePageInitFnMap map[string]func(*Context)
 }
 
+func (v *V) logFatal(format string, a ...any) {
+	log.Printf("[fatal] msg=%q", fmt.Sprintf(format, a...))
+}
+
 func (v *V) logErr(c *Context, format string, a ...any) {
 	cRef := ""
 	if c != nil && c.id != "" {
@@ -119,8 +124,8 @@ func (v *V) AppendToFoot(elements ...h.H) {
 	}
 }
 
-// Page registers a route and its associated page handler.
-// The handler receives a *Context to define UI, signals, and actions.
+// Page registers a route and its associated page handler. The handler receives a *Context
+// that defines state, UI, signals, and actions.
 //
 // Example:
 //
@@ -130,6 +135,20 @@ func (v *V) AppendToFoot(elements ...h.H) {
 //		})
 //	})
 func (v *V) Page(route string, initContextFn func(c *Context)) {
+	// check for panics
+	func() {
+		defer func() {
+			if err := recover(); err != nil {
+				v.logFatal("failed to register page with init func that panics: %v", err)
+				panic(err)
+			}
+		}()
+		c := newContext("", "", v)
+		initContextFn(c)
+		c.view()
+	}()
+
+	// save page init function allows devmode to restore persisted ctx later
 	if v.cfg.DevMode {
 		v.devModePageInitFnMap[route] = initContextFn
 	}
@@ -145,10 +164,15 @@ func (v *V) Page(route string, initContextFn func(c *Context)) {
 		if v.cfg.DevMode {
 			v.devModePersist(c)
 		}
-		v.AppendToHead(h.Meta(h.Data("signals", fmt.Sprintf("{'via-ctx':'%s'}", id))))
-		v.AppendToHead(h.Meta(h.Data("init", "@get('/_sse')")))
-		v.AppendToHead(h.Meta(h.Data("init", fmt.Sprintf(`window.addEventListener('beforeunload', (evt) => {
-			navigator.sendBeacon('/_session/close', '%s');});`, c.id))))
+		headElements := []h.H{}
+		headElements = append(headElements, v.documentHeadIncludes...)
+		headElements = append(headElements,
+			h.Meta(h.Data("signals", fmt.Sprintf("{'via-ctx':'%s'}", id))),
+			h.Meta(h.Data("init", "@get('/_sse')")),
+			h.Meta(h.Data("init", fmt.Sprintf(`window.addEventListener('beforeunload', (evt) => {
+			navigator.sendBeacon('/_session/close', '%s');});`, c.id))),
+		)
+
 		bodyElements := []h.H{c.view()}
 		bodyElements = append(bodyElements, v.documentFootIncludes...)
 		if v.cfg.DevMode {
@@ -158,7 +182,7 @@ func (v *V) Page(route string, initContextFn func(c *Context)) {
 		}
 		view := h.HTML5(h.HTML5Props{
 			Title:     v.cfg.DocumentTitle,
-			Head:      v.documentHeadIncludes,
+			Head:      headElements,
 			Body:      bodyElements,
 			HTMLAttrs: []h.H{},
 		})
@@ -175,11 +199,11 @@ func (v *V) registerCtx(c *Context) {
 	}
 	v.contextRegistry[c.id] = c
 	v.logDebug(c, "new context added to registry")
-	v.summarize()
+	v.logDebug(nil, "number of sessions in registry: %d", v.currSessionNum())
 }
 
-func (v *V) summarize() {
-	fmt.Println("Have", len(v.contextRegistry), "sessions")
+func (v *V) currSessionNum() int {
+	return len(v.contextRegistry)
 }
 
 func (v *V) unregisterCtx(id string) {
@@ -190,7 +214,7 @@ func (v *V) unregisterCtx(id string) {
 	}
 	v.logDebug(nil, "ctx '%s' removed from registry", id)
 	delete(v.contextRegistry, id)
-	v.summarize()
+	v.currSessionNum()
 }
 
 func (v *V) getCtx(id string) (*Context, error) {
@@ -251,6 +275,37 @@ func (v *V) devModePersist(c *Context) {
 	v.logDebug(c, "devmode persisted ctx to file")
 }
 
+func (v *V) devModeRemovePersisted(c *Context) {
+	p := filepath.Join(".via", "devmode", "ctx.json")
+
+	// load persisted list from file, or empty list if file not found
+	file, err := os.Open(p)
+	ctxRegMap := make(map[string]string)
+	if err == nil {
+		json.NewDecoder(file).Decode(&ctxRegMap)
+	}
+	file.Close()
+
+	// remove ctx to persisted list
+	if _, ok := ctxRegMap[c.id]; !ok {
+		delete(ctxRegMap, c.id)
+	}
+
+	// write persisted list to file
+	file, err = os.Create(p)
+	if err != nil {
+		v.logErr(c, "devmode failed to remove percisted ctx: %v", err)
+
+	}
+	defer file.Close()
+
+	encoder := json.NewEncoder(file)
+	if err := encoder.Encode(ctxRegMap); err != nil {
+		v.logErr(c, "devmode failed to remove persisted ctx")
+	}
+	v.logDebug(c, "devmode removed persisted ctx from file")
+}
+
 func (v *V) devModeRestore() {
 	p := filepath.Join(".via", "devmode", "ctx.json")
 	file, err := os.Open(p)
@@ -330,18 +385,16 @@ func New() *V {
 
 		v.logDebug(c, "SSE connection established")
 
-		go func() {
-			if v.cfg.DevMode {
-				c.Sync()
-			} else {
-				c.SyncSignals()
-			}
-		}()
+		if v.cfg.DevMode {
+			c.Sync()
+		} else {
+			c.SyncSignals()
+		}
 
 		for {
 			select {
 			case <-sse.Context().Done():
-				v.logDebug(c, "SSE context done, exiting handler loop")
+				v.logDebug(c, "SSE connection ended")
 				return
 			case patch, ok := <-c.patchChan:
 				if !ok {
@@ -365,6 +418,8 @@ func New() *V {
 						return
 					}
 				}
+			default:
+				time.Sleep(100 * time.Microsecond)
 			}
 		}
 	})
@@ -410,6 +465,7 @@ func New() *V {
 			return
 		}
 		v.logDebug(c, "session close event triggered")
+		v.devModeRemovePersisted(c)
 		v.unregisterCtx(c.id)
 
 	})

via_test.go

@@ -35,6 +35,7 @@ func TestDatastarJS(t *testing.T) {
 
 	assert.Equal(t, http.StatusOK, w.Code)
 	assert.Equal(t, "application/javascript", w.Header().Get("Content-Type"))
+	assert.Contains(t, w.Body.String(), "🖕JS_DS🚀")
 }
 
 func TestSignal(t *testing.T) {
@@ -106,3 +107,10 @@ func TestSyncSignals(t *testing.T) {
 	patch := <-ctx.patchChan
 	assert.Equal(t, patch.content, fmt.Sprintf(`{"%s":"updated"}`, sig.ID()))
 }
+
+func TestPage_PanicsOnNoView(t *testing.T) {
+	assert.Panics(t, func() {
+		v := New()
+		v.Page("/", func(c *Context) {})
+	})
+}