add_edge() — langchain Function Reference

Architecture documentation for the add_edge() function in graph.py from the langchain codebase.

Function python LangChainCore Runnables

Entity Profile

LangChainCore→ Runnables→ add_edge() — langchain Function Reference

Dependency Diagram

graph TD
  f1aa2cc8_a959_f2b6_f36e_f96286c417ed["add_edge()"]
  646f3bb5_a594_563e_cfbf_e18bdc9efb90["Graph"]
  f1aa2cc8_a959_f2b6_f36e_f96286c417ed -->|defined in| 646f3bb5_a594_563e_cfbf_e18bdc9efb90
  style f1aa2cc8_a959_f2b6_f36e_f96286c417ed fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/runnables/graph.py lines 351–382

    def add_edge(
        self,
        source: Node,
        target: Node,
        data: Stringifiable | None = None,
        conditional: bool = False,  # noqa: FBT001,FBT002
    ) -> Edge:
        """Add an edge to the graph and return it.

        Args:
            source: The source node of the edge.
            target: The target node of the edge.
            data: Optional data associated with the edge.
            conditional: Whether the edge is conditional.

        Returns:
            The edge that was added to the graph.

        Raises:
            ValueError: If the source or target node is not in the graph.
        """
        if source.id not in self.nodes:
            msg = f"Source node {source.id} not in graph"
            raise ValueError(msg)
        if target.id not in self.nodes:
            msg = f"Target node {target.id} not in graph"
            raise ValueError(msg)
        edge = Edge(
            source=source.id, target=target.id, data=data, conditional=conditional
        )
        self.edges.append(edge)
        return edge