76 lines
2.6 KiB
Python
76 lines
2.6 KiB
Python
import uuid
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from sqlalchemy import CheckConstraint, ForeignKey, Index, String, Text, text
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from sqlalchemy.dialects.postgresql import UUID
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from sqlalchemy.orm import Mapped, mapped_column, relationship
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from api.models.base import Base, TimestampMixin, new_uuid
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class WorkstreamDependency(Base, TimestampMixin):
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"""Directed dependency edge: `from_workstream` depends on a workstream or task.
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Semantics: the target must reach a satisfactory state before `from_workstream`
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can fully proceed. Hard deletes are intentional —
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removing an edge removes a constraint, not information.
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"""
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__tablename__ = "workstream_dependencies"
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__table_args__ = (
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CheckConstraint(
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"(to_workstream_id IS NOT NULL AND to_task_id IS NULL) "
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"OR (to_workstream_id IS NULL AND to_task_id IS NOT NULL)",
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name="ck_ws_dep_exactly_one_target",
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),
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Index(
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"uq_ws_dep_workstream_target",
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"from_workstream_id",
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"to_workstream_id",
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"relationship_type",
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unique=True,
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postgresql_where=text("to_workstream_id IS NOT NULL"),
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),
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Index(
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"uq_ws_dep_task_target",
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"from_workstream_id",
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"to_task_id",
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"relationship_type",
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unique=True,
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postgresql_where=text("to_task_id IS NOT NULL"),
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),
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)
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id: Mapped[uuid.UUID] = mapped_column(
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UUID(as_uuid=True), primary_key=True, default=new_uuid
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)
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from_workstream_id: Mapped[uuid.UUID] = mapped_column(
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UUID(as_uuid=True),
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ForeignKey("workstreams.id", ondelete="CASCADE"),
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nullable=False,
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index=True,
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)
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to_workstream_id: Mapped[uuid.UUID | None] = mapped_column(
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UUID(as_uuid=True),
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ForeignKey("workstreams.id", ondelete="CASCADE"),
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nullable=True,
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index=True,
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)
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to_task_id: Mapped[uuid.UUID | None] = mapped_column(
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UUID(as_uuid=True),
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ForeignKey("tasks.id", ondelete="CASCADE"),
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nullable=True,
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index=True,
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)
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relationship_type: Mapped[str] = mapped_column(
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String(40), nullable=False, default="blocks", server_default="blocks", index=True
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)
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description: Mapped[str | None] = mapped_column(Text, nullable=True)
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from_workstream: Mapped["Workstream"] = relationship( # noqa: F821
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"Workstream", foreign_keys=[from_workstream_id]
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)
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to_workstream: Mapped["Workstream | None"] = relationship( # noqa: F821
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"Workstream", foreign_keys=[to_workstream_id]
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)
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to_task: Mapped["Task | None"] = relationship("Task", foreign_keys=[to_task_id]) # noqa: F821
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