feat(16.2-07): purge the host site cache on every admin post and category write

- posts: FormAfterCreate/Update purge after the content_html translations,
  new FormAfterDelete; categories: FormAfterCreate and FormAfterDelete
- NewSiteCachePurger refuses half configuration, non-http(s) URLs, user
  info, fragments, http to a non-loopback host and tokens under 32 chars;
  Boot logs the endpoint host and path once
- TestPostsAdminPurgesSiteCache smoke test
- README: Configuration section (keys, contract, timing, scope), API rows

controllers/admin_registry.go

@@ -30,12 +30,18 @@ func init() {
 	var _ pact.FormAfterCreate = postsAdminController{}
 	var _ pact.FormAfterUpdate = postsAdminController{}
 	var _ pact.FormBeforeDelete = postsAdminController{}
+	var _ pact.FormAfterDelete = postsAdminController{}
 	var _ pact.HasAdminActions = postsAdminController{}
 	var _ cabana.FieldRelationProvider = postsAdminController{}
 
 	var _ pact.AdminController = categoriesAdminController{}
 	var _ pact.AdminPermissioned = categoriesAdminController{}
 	var _ pact.AdminRecordSource = categoriesAdminController{}
+	var _ pact.FormBeforeCreate = categoriesAdminController{}
+	var _ pact.FormBeforeUpdate = categoriesAdminController{}
+	var _ pact.FormAfterCreate = categoriesAdminController{}
+	var _ pact.FormAfterUpdate = categoriesAdminController{}
+	var _ pact.FormAfterDelete = categoriesAdminController{}
 	var _ cabana.FieldRelationProvider = categoriesAdminController{}
 
 	var _ pact.AdminController = tagsAdminController{}

controllers/categories.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"strings"
 
+	"git.golem15.com/golem15/sm-journal-plugin/classes"
 	"git.golem15.com/golem15/sm-journal-plugin/models"
 	"git.golem15.com/golem15/summercms/modules/backpack"
 	"git.golem15.com/golem15/summercms/modules/cabana"
@@ -60,14 +61,31 @@ func (categoriesAdminController) FormBeforeUpdate(ctx context.Context, model any
 	return prepareCategoryWrite(cat)
 }
 
+// FormAfterCreate purges the host site's page caches once the save
+// transaction commits (G-16.2-2, D-19).
+func (c categoriesAdminController) FormAfterCreate(ctx context.Context, model any) error {
+	return c.purgeAfterCommit(ctx, model)
+}
+
 // FormAfterUpdate purges the host site's page caches once the save
 // transaction commits (G-16.2-2, D-19).
 func (c categoriesAdminController) FormAfterUpdate(ctx context.Context, model any) error {
+	return c.purgeAfterCommit(ctx, model)
+}
+
+// FormAfterDelete purges the host site's page caches once the delete
+// commits.
+func (c categoriesAdminController) FormAfterDelete(ctx context.Context, model any) error {
+	return c.purgeAfterCommit(ctx, model)
+}
+
+func (c categoriesAdminController) purgeAfterCommit(ctx context.Context, model any) error {
 	cat, ok := model.(*models.Category)
 	if !ok || cat == nil {
 		return errors.New("categories admin: form model is not a category")
 	}
-	purgeSiteCache(ctx, c.app, "category", cat.Slug)
+	purger, tx := siteCachePurger(ctx, c.app)
+	classes.PurgeSiteCacheAfterCommit(ctx, tx, purger, "category", cat.Slug)
 	return nil
 }
 
@@ -95,6 +113,8 @@ var (
 	_ pact.AdminRecordSource       = categoriesAdminController{}
 	_ pact.FormBeforeCreate        = categoriesAdminController{}
 	_ pact.FormBeforeUpdate        = categoriesAdminController{}
+	_ pact.FormAfterCreate         = categoriesAdminController{}
 	_ pact.FormAfterUpdate         = categoriesAdminController{}
+	_ pact.FormAfterDelete         = categoriesAdminController{}
 	_ cabana.FieldRelationProvider = categoriesAdminController{}
 )

controllers/posts.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"strconv"
 
+	"git.golem15.com/golem15/sm-journal-plugin/classes"
 	"git.golem15.com/golem15/sm-journal-plugin/console"
 	"git.golem15.com/golem15/sm-journal-plugin/models"
 	"git.golem15.com/golem15/summercms/modules/backpack"
@@ -226,16 +227,41 @@ func preparePostWrite(ctx context.Context, post *models.Post) error {
 }
 
 // FormAfterCreate writes content_html for every non-default locale whose
-// content the save wrote (D-02).
+// content the save wrote (D-02), then registers the host site cache purge
+// for after the commit.
 func (c postsAdminController) FormAfterCreate(ctx context.Context, model any) error {
-	return c.writeContentHTMLTranslations(ctx, model)
+	return c.afterPostWrite(ctx, model)
 }
 
 // FormAfterUpdate writes content_html for every non-default locale whose
 // content the save wrote (D-02). Untouched locales are not listed and keep
-// their content_html.
+// their content_html. It then registers the host site cache purge for after
+// the commit; an untouched save purges too, which is harmless.
 func (c postsAdminController) FormAfterUpdate(ctx context.Context, model any) error {
-	return c.writeContentHTMLTranslations(ctx, model)
+	return c.afterPostWrite(ctx, model)
+}
+
+// FormAfterDelete registers the host site cache purge for after the delete
+// commits.
+func (c postsAdminController) FormAfterDelete(ctx context.Context, model any) error {
+	post, ok := model.(*models.Post)
+	if !ok || post == nil {
+		return errors.New("posts admin: form model is not a post")
+	}
+	purger, tx := siteCachePurger(ctx, c.app)
+	classes.PurgeSiteCacheAfterCommit(ctx, tx, purger, "post", post.Slug)
+	return nil
+}
+
+func (c postsAdminController) afterPostWrite(ctx context.Context, model any) error {
+	if err := c.writeContentHTMLTranslations(ctx, model); err != nil {
+		return err
+	}
+	if post, ok := model.(*models.Post); ok && post != nil {
+		purger, tx := siteCachePurger(ctx, c.app)
+		classes.PurgeSiteCacheAfterCommit(ctx, tx, purger, "post", post.Slug)
+	}
+	return nil
 }
 
 // writeContentHTMLTranslations stores each written non-default content

controllers/site_cache.go

@@ -6,27 +6,28 @@ import (
 	"git.golem15.com/golem15/sm-journal-plugin/classes"
 	"git.golem15.com/golem15/summercms/modules/backpack"
 	"git.golem15.com/golem15/summercms/modules/cabana"
+	"gorm.io/gorm"
 )
 
-// purgeSiteCache registers a site cache purge for one saved entity to run
-// after the save transaction commits. Without a published
-// *classes.SiteCachePurger (no purge configured) or outside a save
-// transaction it does nothing.
-func purgeSiteCache(ctx context.Context, app func() *backpack.App, kind, slug string) {
+// siteCachePurger returns the published *classes.SiteCachePurger and the
+// save transaction of ctx, for classes.PurgeSiteCacheAfterCommit. Without a
+// purger (no purge configured) or outside a save transaction it returns a
+// nil purger, which PurgeSiteCacheAfterCommit ignores.
+func siteCachePurger(ctx context.Context, app func() *backpack.App) (*classes.SiteCachePurger, *gorm.DB) {
 	if app == nil {
-		return
+		return nil, nil
 	}
 	a := app()
 	if a == nil {
-		return
+		return nil, nil
 	}
 	purger, ok := a.Lookup[*classes.SiteCachePurger]()
 	if !ok || purger == nil {
-		return
+		return nil, nil
 	}
 	tx, ok := cabana.TxFromContext(ctx)
 	if !ok {
-		return
+		return nil, nil
 	}
-	classes.PurgeSiteCacheAfterCommit(ctx, tx, purger, kind, slug)
+	return purger, tx
 }