table follow requires the id length of user

app/models/base.py

@@ -27,7 +27,7 @@ def encode_base62(num: int, length: int = None) -> str:
     return res
 
 
-def encode_tablename_to_prefix(tablename: str, length: int = 3) -> str:
+def encode_tablename_to_prefix(tablename: str, length: int) -> str:
     """
     将表名 encode 成固定长度的前缀，使用 MD5 拿到表名的唯一哈希值，转为整数后用 Base62 截取前 N 位
     """
@@ -39,18 +39,17 @@ def encode_tablename_to_prefix(tablename: str, length: int = 3) -> str:
     num = int(hex_digest, 16)
     
     # 转为 Base62 字符串
-    b62_str = encode_base62(num, length=length)
-    
-    # 截取固定长度（例如 3 位）作为该表的专属代码
-    return b62_str[:length]
+    return encode_base62(num, length=length)
 
 
-def gen_convex_payload() -> str:
-    """生成 128位 ULID 转 Base62 的趋势递增 Payload"""
+def gen_convex_payload(length: int) -> str:
+    """生成固定长度的 ULID Payload"""
     u = ulid.new()
-    return encode_base62(u.int)
+    return encode_base62(u.int, length=length)
 
 
+# --- 注入器类 ---
+
 class AutoID:
     """
     全自动 Convex 风格 ID 注入器
@@ -61,6 +60,11 @@ class AutoID:
     _id_prefix_len = 3   # 前缀长度
     _id_payload_len = 22 # 主体长度（ULID 转 Base62 最大约 22 位）
     
+    @classmethod
+    def id_length(cls) -> int:
+        """返回当前类 ID 的总长度"""
+        return cls._id_prefix_len + cls._id_payload_len
+    
     @declared_attr
     def id(cls):
         # 运行时动态获取子类的 __tablename__
@@ -68,18 +72,11 @@ class AutoID:
         # 获取子类配置的长度
         p_len = cls._id_prefix_len
         s_len = cls._id_payload_len
-        
-        # 将表名编码为固定前缀（例如 "users" -> "7X1"）
-        hasher = hashlib.md5(tablename.encode("utf-8"))
-        table_num = int(hasher.hexdigest(), 16)
-        table_prefix = encode_base62(table_num, length=p_len)
+        prefix = encode_tablename_to_prefix(tablename, length=p_len)
         
         # 核心工厂函数：拼接【编码后的表前缀】和【递增Payload】
         def id_factory():
-            # 生成固定长度的 Payload
-            u = ulid.new()
-            payload = encode_base62(u.int, length=s_len)
-            # 直接拼接，不带下划线
-            return f"{table_prefix}{payload}"
+            payload = gen_convex_payload(length=s_len)
+            return f"{prefix}{payload}"
 
-        return Column(String(p_len + s_len), primary_key=True, default=id_factory)
+        return Column(String(cls.id_length()), primary_key=True, default=id_factory)

app/models/follow.py

@@ -1,13 +1,28 @@
+from typing import TYPE_CHECKING
 from sqlalchemy import Column, DateTime, String, ForeignKey, UniqueConstraint
 from sqlalchemy.sql import func
 from .base import AutoID, Base
 
+# 只有在静态检查时才导入
+# 运行阶段这段代码会被跳过，彻底避免循环导入
+# 不确定是否用得上，但感觉这是个好习惯，尤其在模型之间有外键关系时
+if TYPE_CHECKING:
+    from .user import User
+
 class Follow(Base, AutoID):
     """用户关注关系表"""
     __tablename__ = "follows"
 
-    follower_id = Column(String(32), ForeignKey("users.id", ondelete="CASCADE"), index=True)
-    followee_id = Column(String(32), ForeignKey("users.id", ondelete="CASCADE"), index=True)
+    follower_id = Column(
+        String(User.id_length()), 
+        ForeignKey("users.id", ondelete="CASCADE"), 
+        index=True
+    )
+    followee_id = Column(
+        String(User.id_length()), 
+        ForeignKey("users.id", ondelete="CASCADE"), 
+        index=True
+    )
     
     created_at = Column(DateTime(timezone=True), server_default=func.now())