02_lesson: Add canSave check function to disable Save Post button

02_lesson_starter/src/features/posts/AddPostForm.js

@@ -25,6 +25,8 @@ const AddPostForm = () => {
     }
   };
 
+  const canSave = Boolean(title) && Boolean(content) && Boolean(userId);
+
   const usersOptions = users.map((user) => (
     <option key={user.id} value={user.id}>
       {user.name}
@@ -55,7 +57,7 @@ const AddPostForm = () => {
           value={content}
           onChange={onContentChanged}
         />
-        <button type="button" onClick={onSavePostClicked}>
+        <button type="button" onClick={onSavePostClicked} disabled={!canSave}>
           Save Post
         </button>
       </form>