v0.1 fastapi: route + model + orm

debug/orm_imp/orm_simple_imp.py

@@ -0,0 +1,97 @@
+class Field:
+    """字段描述符：记录列名和类型"""
+    def __init__(self, column_type):
+        self.column_type = column_type
+        self.name = None
+
+    def __set_name__(self, owner, name):
+        self.name = name
+
+    def __get__(self, instance, owner):
+        if instance is None:
+            return self
+        return instance.__dict__.get(self.name)
+
+    def __set__(self, instance, value):
+        instance.__dict__[self.name] = value
+
+
+class IntegerField(Field):
+    def __init__(self, primary_key=False):
+        super().__init__("INTEGER")
+        self.primary_key = primary_key
+
+
+class StringField(Field):
+    def __init__(self, max_length=255):
+        super().__init__(f"VARCHAR({max_length})")
+
+
+class ModelMeta(type):
+    """元类：在类创建时收集字段，生成 SQL"""
+    def __new__(mcs, name, bases, namespace):
+        # 跳过基类 Model 本身
+        if name == "Model":
+            return super().__new__(mcs, name, bases, namespace)
+
+        fields = {}
+        for key, value in namespace.items():
+            if isinstance(value, Field):
+                fields[key] = value
+
+        # 把收集到的字段挂到类上
+        namespace["_fields"] = fields
+        namespace["_table"] = name.lower() + "s"
+
+        cls = super().__new__(mcs, name, bases, namespace)
+        return cls
+
+
+class Model(metaclass=ModelMeta):
+    """所有模型的基类"""
+
+    @classmethod
+    def create_table_sql(cls):
+        columns = []
+        for name, field in cls._fields.items():
+            col = f"{name} {field.column_type}"
+            if isinstance(field, IntegerField) and field.primary_key:
+                col += " PRIMARY KEY AUTOINCREMENT"
+            columns.append(col)
+        return f"CREATE TABLE IF NOT EXISTS {cls._table} ({', '.join(columns)});"
+
+    @classmethod
+    def insert_sql(cls, **kwargs):
+        keys = ", ".join(kwargs.keys())
+        values = ", ".join(
+            f"'{v}'" if isinstance(v, str) else str(v)
+            for v in kwargs.values()
+        )
+        return f"INSERT INTO {cls._table} ({keys}) VALUES ({values});"
+
+
+# ===== 使用 =====
+class User(Model):
+    id = IntegerField(primary_key=True)
+    name = StringField(50)
+    email = StringField(100)
+
+
+class Post(Model):
+    id = IntegerField(primary_key=True)
+    title = StringField(200)
+    user_id = IntegerField()
+
+
+print(User.create_table_sql())
+# CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(50), email VARCHAR(100));
+
+print(User.insert_sql(name="Alice", email="alice@example.com"))
+# INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com');
+
+print(Post.create_table_sql())
+# CREATE TABLE IF NOT EXISTS posts (id INTEGER PRIMARY KEY AUTOINCREMENT, title VARCHAR(200), user_id INTEGER);
+
+print(Post.insert_sql(title="orm is best", user_id=1))
+print(Post.insert_sql(title="orm simple imp", user_id=1))
+print(Post.insert_sql(title="mete class is the base", user_id=1))