91 lines
4.1 KiB
Python
91 lines
4.1 KiB
Python
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"""就业信息表（需求 2.3）。
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关于「学生姓名、学生班级属于冗余字段」的处理
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--------------------------------------------------------------------------
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需求点名要自行设计表结构来平衡查询效率与一致性。这里的取舍：
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* **学生姓名不落库。** 它是 student.name 的投影，1:1 关系，
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JOIN 一次的成本可以忽略；而一旦落库，改名就会两处不一致，收益为零。查询接口
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统一 `JOIN student` 取名字。
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* **班级落库（class_id 而非 class_name）。** 因为"按班级筛就业、按班级算就业率/
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平均就业时长"是高频统计场景，每次 JOIN student 再 JOIN clazz 成本更高；
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而且存 id 不存名字，班级改名不会导致脏数据。
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代价是学生转班时要同步——由 ``EmploymentService.sync_class_id()`` 在学生
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接口里兜住，不给"记得改"留口子。
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* **就业时长不落库**，= offer_date - open_date，用 SQL DATEDIFF 或 Python 现算。
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状态联动（需求 2.3 可选扩展，这里是必做）：
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登记就业 -> 有 open_date 则学生 status=2（进入就业），
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-> 有 offer_date 则学生 status=3（已就业）
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删除就业记录 -> 学生状态回退（3 -> 2 -> 1），不允许跨级跳。
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"""
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from __future__ import annotations
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from datetime import date
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from decimal import Decimal
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from sqlalchemy import Date, ForeignKey, Numeric, String, Text
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from sqlalchemy.orm import Mapped, mapped_column, relationship
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from app.model.base import Base, SoftDeleteMixin, TimestampMixin
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class Employment(Base, TimestampMixin, SoftDeleteMixin):
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__tablename__ = "employment"
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__table_args__ = {"comment": "学生就业信息表"}
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id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
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stu_id: Mapped[int] = mapped_column(
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ForeignKey("student.id"), unique=True, nullable=False, index=True,
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comment="学生ID（一学生一条就业记录）",
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)
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class_id: Mapped[int | None] = mapped_column(
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ForeignKey("clazz.id"), index=True,
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comment="班级ID（冗余，用于按班统计，转班时由 service 同步）",
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)
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open_date: Mapped[date | None] = mapped_column(Date, comment="就业开放时间")
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offer_date: Mapped[date | None] = mapped_column(Date, comment="offer 下发时间")
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company: Mapped[str | None] = mapped_column(String(80), index=True, comment="就业公司名称")
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salary: Mapped[Decimal | None] = mapped_column(Numeric(10, 2), index=True, comment="就业薪资（元/月）")
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position: Mapped[str | None] = mapped_column(String(50), comment="岗位名称")
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city: Mapped[str | None] = mapped_column(String(30), comment="就业城市")
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remark: Mapped[str | None] = mapped_column(Text, comment="备注")
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student: Mapped["Student"] = relationship(back_populates="employment", lazy="joined") # noqa: F821
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klass: Mapped["Clazz"] = relationship(lazy="joined", foreign_keys=[class_id]) # noqa: F821
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# ---------------- 出参派生字段 ----------------
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@property
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def student_name(self) -> str | None:
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return self.student.name if self.student else None
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@property
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def stu_no(self) -> str | None:
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return self.student.stu_no if self.student else None
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@property
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def student_status(self) -> int | None:
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return self.student.status if self.student else None
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@property
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def student_status_text(self) -> str | None:
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return self.student.status_text if self.student else None
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@property
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def class_name(self) -> str | None:
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# 冗余字段只存了 id，名字实时取，保证与班级表一致
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return self.klass.name if self.klass and self.klass.is_del == 0 else None
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@property
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def duration_days(self) -> int | None:
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"""就业时长 = offer 下发时间 - 就业开放时间（天）。"""
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if self.open_date and self.offer_date:
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return (self.offer_date - self.open_date).days
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return None
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@property
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def salary_wan(self) -> float | None:
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return round(float(self.salary) / 10000, 2) if self.salary is not None else None
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