is possible add node or edge dynamic without restart app

[weiminw]

is possible add node or edge dynamic without restart app

[dosubot[bot]]

Hey @weiminw, long time no see! Hope you're coding up a storm 🌪️

Yes, it is indeed possible to add a node or edge dynamically without restarting the app in LangChain. The Graph class in the graph.py file provides methods add_node and add_edge that allow for the dynamic addition of nodes and edges to the graph instance. These methods modify the graph's state in memory, so any changes (like adding nodes or edges) take effect immediately without the need to restart the application.

Here's how you can add a node:

# Assuming `graph` is an instance of the Graph class
new_node_data = ... # This should be an instance of BaseModel or RunnableType
new_node = graph.add_node(data=new_node_data)

And here's how you can add an edge between two nodes:

# Assuming `source_node` and `target_node` are Node instances within `graph`
new_edge = graph.add_edge(source=source_node, target=target_node)

These operations are performed at runtime, and their effects are reflected immediately in the Graph instance. You can find more details in the source code here.

Sources

• libs/core/langchain_core/runnables/graph.py

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[weiminw]

well，could i also remove node or edge from graph dynamic on runtime？

[ariel-frischer]

Will this actually work? Do you need to run graph.compile() again?
@dosubot

[ariel-frischer]

Found this tidbit:
.../lib/python3.11/site-packages/langgraph/graph/state.py

        if self.compiled:
            logger.warning(
                "Adding a node to a graph that has already been compiled. This will "
                "not be reflected in the compiled graph."
            )

So seems like this won't work. I will try compiling a new subgraph dynamically instead.