Neaten up the blog site example

And fix some issues.

examples/blog-site/model.scm

@@ -28,6 +28,9 @@ connection to DATABASE-FILE."
        (sqlite-busy-timeout db 5000)
        (sqlite-exec db "PRAGMA journal_mode=WAL")
        (sqlite-exec db "PRAGMA foreign_keys=ON")
+
+       (db-init! db)
+
        (list db)))
    #:thread-destructor
    (lambda (db)
@@ -44,18 +47,15 @@ SQLite connection.  Returns whatever PROC returns."
 ;;; Schema
 ;;;
 
-(define (db-init! pool)
-  "Create the schema if it doesn't exist."
-  (call-with-db pool
-    (lambda (db)
-      (sqlite-exec db "
-        CREATE TABLE IF NOT EXISTS posts (
-          id INTEGER PRIMARY KEY AUTOINCREMENT,
-          title TEXT NOT NULL,
-          body TEXT NOT NULL,
-          image_url TEXT,
-          created_at TEXT NOT NULL DEFAULT (datetime('now'))
-        )"))))
+(define (db-init! db)
+  (sqlite-exec db "
+CREATE TABLE IF NOT EXISTS posts (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  title TEXT NOT NULL,
+  body TEXT NOT NULL,
+  image_url TEXT,
+  created_at TEXT NOT NULL DEFAULT (datetime('now'))
+)"))
 
 ;;;
 ;;; Row conversions
@@ -118,6 +118,14 @@ newest first."
             (sqlite-finalize stmt)
             (vector-ref row 0)))))))
 
+(define (sqlite-changes db)
+  "Return the number of rows changed by the most recent INSERT, UPDATE,
+or DELETE statement on DB."
+  (let ((stmt (sqlite-prepare db "SELECT changes()")))
+    (let ((row (sqlite-step stmt)))
+      (sqlite-finalize stmt)
+      (vector-ref row 0))))
+
 (define (db-update-post! pool id title body image-url)
   "Update the post with ID.  Returns #t if a row was changed, #f otherwise."
   (call-with-db pool