添加chapter和lesson

Html/apps/models/material.py

@@ -0,0 +1,24 @@
+from pydantic import BaseModel
+from typing import List, Optional
+from datetime import datetime
+from bson import ObjectId
+
+class Lesson(BaseModel):
+    lesson_name: str
+    markdown_lesson_file_link: str
+    markdown_prompt_file_name: str
+    markdown_score_prompt_file_link: str
+
+class Chapter(BaseModel):
+    chapter_name: str
+    lessons: List[Lesson]
+
+class Material(BaseModel):
+    _id: ObjectId
+    name: str
+    description: Optional[str] = None
+    teacher_id: str
+    created_at: datetime
+    updated_at: datetime
+    image_url: Optional[str] = None # 封面图片的url
+    chapters: List[Chapter]