Make web context initialize correctly for different cases (#26726)

The web context (modules/context.Context) is quite complex, it's
difficult for the callers to initialize correctly.

This PR introduces a `NewWebContext` function, to make sure the web
context have the same behavior for different cases.

modules/context/context.go

@@ -107,6 +107,29 @@ func GetValidateContext(req *http.Request) (ctx *ValidateContext) {
 	return ctx
 }
 
+func NewTemplateContextForWeb(ctx *Context) TemplateContext {
+	tmplCtx := NewTemplateContext(ctx)
+	tmplCtx["Locale"] = ctx.Base.Locale
+	tmplCtx["AvatarUtils"] = templates.NewAvatarUtils(ctx)
+	return tmplCtx
+}
+
+func NewWebContext(base *Base, render Render, session session.Store) *Context {
+	ctx := &Context{
+		Base:    base,
+		Render:  render,
+		Session: session,
+
+		Cache: mc.GetCache(),
+		Link:  setting.AppSubURL + strings.TrimSuffix(base.Req.URL.EscapedPath(), "/"),
+		Repo:  &Repository{PullRequest: &PullRequest{}},
+		Org:   &Organization{},
+	}
+	ctx.TemplateContext = NewTemplateContextForWeb(ctx)
+	ctx.Flash = &middleware.Flash{DataStore: ctx, Values: url.Values{}}
+	return ctx
+}
+
 // Contexter initializes a classic context for a request.
 func Contexter() func(next http.Handler) http.Handler {
 	rnd := templates.HTMLRenderer()
@@ -127,21 +150,8 @@ func Contexter() func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
 			base, baseCleanUp := NewBaseContext(resp, req)
-			ctx := &Context{
-				Base:    base,
-				Cache:   mc.GetCache(),
-				Link:    setting.AppSubURL + strings.TrimSuffix(req.URL.EscapedPath(), "/"),
-				Render:  rnd,
-				Session: session.GetSession(req),
-				Repo:    &Repository{PullRequest: &PullRequest{}},
-				Org:     &Organization{},
-			}
 			defer baseCleanUp()
-
-			// TODO: "install.go" also shares the same logic, which should be refactored to a general function
-			ctx.TemplateContext = NewTemplateContext(ctx)
-			ctx.TemplateContext["Locale"] = ctx.Locale
-			ctx.TemplateContext["AvatarUtils"] = templates.NewAvatarUtils(ctx)
+			ctx := NewWebContext(base, rnd, session.GetSession(req))
 
 			ctx.Data.MergeFrom(middleware.CommonTemplateContextData())
 			ctx.Data["Context"] = ctx // TODO: use "ctx" in template and remove this
@@ -172,8 +182,7 @@ func Contexter() func(next http.Handler) http.Handler {
 				}
 			}
 
-			// prepare an empty Flash message for current request
-			ctx.Flash = &middleware.Flash{DataStore: ctx, Values: url.Values{}}
+			// if there are new messages in the ctx.Flash, write them into cookie
 			ctx.Resp.Before(func(resp ResponseWriter) {
 				if val := ctx.Flash.Encode(); val != "" {
 					middleware.SetSiteCookie(ctx.Resp, CookieNameFlash, val, 0)

modules/context/package.go

@@ -154,12 +154,10 @@ func PackageContexter() func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
 			base, baseCleanUp := NewBaseContext(resp, req)
-			ctx := &Context{
-				Base:   base,
-				Render: renderer, // it is still needed when rendering 500 page in a package handler
-			}
 			defer baseCleanUp()
 
+			// it is still needed when rendering 500 page in a package handler
+			ctx := NewWebContext(base, renderer, nil)
 			ctx.Base.AppendContextValue(WebContextKey, ctx)
 			next.ServeHTTP(ctx.Resp, ctx.Req)
 		})

modules/test/context_tests.go

@@ -45,14 +45,12 @@ func MockContext(t *testing.T, reqPath string) (*context.Context, *httptest.Resp
 	resp := httptest.NewRecorder()
 	req := mockRequest(t, reqPath)
 	base, baseCleanUp := context.NewBaseContext(resp, req)
+	_ = baseCleanUp // during test, it doesn't need to do clean up. TODO: this can be improved later
 	base.Data = middleware.GetContextData(req.Context())
 	base.Locale = &translation.MockLocale{}
-	ctx := &context.Context{
-		Base:   base,
-		Render: &mockRender{},
-		Flash:  &middleware.Flash{Values: url.Values{}},
-	}
-	_ = baseCleanUp // during test, it doesn't need to do clean up. TODO: this can be improved later
+
+	ctx := context.NewWebContext(base, &MockRender{}, nil)
+	ctx.Flash = &middleware.Flash{Values: url.Values{}}
 
 	chiCtx := chi.NewRouteContext()
 	ctx.Base.AppendContextValue(chi.RouteCtxKey, chiCtx)
@@ -148,13 +146,13 @@ func LoadGitRepo(t *testing.T, ctx *context.Context) {
 	assert.NoError(t, err)
 }
 
-type mockRender struct{}
+type MockRender struct{}
 
-func (tr *mockRender) TemplateLookup(tmpl string, _ gocontext.Context) (templates.TemplateExecutor, error) {
+func (tr *MockRender) TemplateLookup(tmpl string, _ gocontext.Context) (templates.TemplateExecutor, error) {
 	return nil, nil
 }
 
-func (tr *mockRender) HTML(w io.Writer, status int, _ string, _ any, _ gocontext.Context) error {
+func (tr *MockRender) HTML(w io.Writer, status int, _ string, _ any, _ gocontext.Context) error {
 	if resp, ok := w.(http.ResponseWriter); ok {
 		resp.WriteHeader(status)
 	}