edge.py

# Copyright 2025 Google LLC.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# models.py
import sqlalchemy as sa
from sqlalchemy.orm import deferred, relationship
from sqlalchemy.types import String, Text

from datacommons_db.models.base import Base


EDGE_TABLE_NAME = "Edge"
OBJECT_VALUE_MAX_LENGTH = 4096


class EdgeModel(Base):
    """
    Represents an edge in the graph.
    """

    __tablename__ = EDGE_TABLE_NAME
    subject_id = sa.Column(
        String(1024), sa.ForeignKey("Node.subject_id"), primary_key=True
    )
    predicate = sa.Column(String(1024), primary_key=True)
    object_id = sa.Column(String(1024), primary_key=True)
    provenance = sa.Column(String(1024), primary_key=True, nullable=False)

    # Define relationships to both source and target nodes
    source_node = relationship(
        "NodeModel", foreign_keys=[subject_id], back_populates="outgoing_edges"
    )

    def __repr__(self):
        return f"<EdgeModel(subject_id='{self.subject_id}', predicate='{self.predicate}', object_id='{self.object_id}')>"