another wip

backend/trading_journal/db_migration.py

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+from __future__ import annotations
+
+from typing import Callable
+
+from sqlalchemy import text
+from sqlalchemy.engine import Engine
+from sqlmodel import SQLModel
+
+# 最新 schema 版本号
+LATEST_VERSION = 1
+
+
+def _mig_0_1(engine: Engine) -> None:
+    """
+    Initial schema: create all tables from SQLModel models.
+    Safe to call on an empty DB; idempotent for missing tables.
+    """
+    # Ensure all models are imported before this is called (import side-effect registers tables)
+    # e.g. trading_journal.models is imported in the caller / app startup.
+    SQLModel.metadata.create_all(bind=engine)
+
+
+# map current_version -> function that migrates from current_version -> current_version+1
+MIGRATIONS: dict[int, Callable[[Engine], None]] = {
+    0: _mig_0_1,
+}
+
+
+def _get_sqlite_user_version(conn) -> int:
+    row = conn.execute(text("PRAGMA user_version")).fetchone()
+    return int(row[0]) if row and row[0] is not None else 0
+
+
+def _set_sqlite_user_version(conn, v: int) -> None:
+    conn.execute(text(f"PRAGMA user_version = {int(v)}"))
+
+
+def run_migrations(engine: Engine, target_version: int | None = None) -> int:
+    """
+    Run migrations up to target_version (or LATEST_VERSION).
+    Returns final applied version.
+    """
+    target = target_version or LATEST_VERSION
+    with engine.begin() as conn:
+        driver = conn.engine.name.lower()
+        if driver == "sqlite":
+            cur_version = _get_sqlite_user_version(conn)
+            while cur_version < target:
+                fn = MIGRATIONS.get(cur_version)
+                if fn is None:
+                    raise RuntimeError(f"No migration from {cur_version} -> {cur_version + 1}")
+                # call migration with Engine (fn should use transactions)
+                fn(engine)
+                _set_sqlite_user_version(conn, cur_version + 1)
+                cur_version += 1
+            return cur_version
+        else:
+            # generic migrations table for non-sqlite
+            conn.execute(
+                text("""
+                CREATE TABLE IF NOT EXISTS migrations (
+                    version INTEGER PRIMARY KEY,
+                    applied_at TEXT DEFAULT CURRENT_TIMESTAMP
+                )
+            """)
+            )
+            row = conn.execute(text("SELECT MAX(version) FROM migrations")).fetchone()
+            cur_version = int(row[0]) if row and row[0] is not None else 0
+            while cur_version < target:
+                fn = MIGRATIONS.get(cur_version)
+                if fn is None:
+                    raise RuntimeError(f"No migration from {cur_version} -> {cur_version + 1}")
+                fn(engine)
+                conn.execute(text("INSERT INTO migrations(version) VALUES (:v)"), {"v": cur_version + 1})
+                cur_version += 1
+            return cur_version