LangChain Code

Use the LangChain Code node to import LangChain. This means if there is functionality you need that n8n hasn't created a node for, you can still use it. By configuring the LangChain Code node connectors you can use it as a normal node, root node or sub-node.

On this page, you'll find the node parameters, guidance on configuring the node, and links to more resources.

Deprecated due to security issues

This node has critical security issues and isn't safe to use. It's deprecated and hidden from the nodes panel. Avoid using it in your workflows.

Not available on Cloud

This node is only available on self-hosted n8n.

Node parameters

Add Code

Add your custom code. Choose either Execute or Supply Data mode. You can only use one mode.

Unlike the Code node, the LangChain Code node doesn't support Python.

• Execute: use the LangChain Code node like n8n's own Code node. This takes input data from the workflow, processes it, and returns it as the node output. This mode requires a main input and output. You must create these connections in Inputs and Outputs.

• Supply Data: use the LangChain Code node as a sub-node, sending data to a root node. This uses an output other than main.

By default, you can't load built-in or external modules in this node. Self-hosted users can enable built-in and external modules.

Inputs

Choose the input types.

The main input is the normal connector found in all n8n workflows. If you have a main input and output set in the node, Execute code is required.

Outputs

Choose the output types.

The main output is the normal connector found in all n8n workflows. If you have a main input and output set in the node, Execute code is required.

Node inputs and outputs configuration

By configuring the LangChain Code node connectors (inputs and outputs) you can use it as an app node, root node or sub-node.

Screenshot of a workflow with four LangChain nodes, configured as different node types

Node type	Inputs	Outputs	Code mode
App node. Similar to the Code node.	Main	Main	Execute
Root node	Main; at least one other type	Main	Execute
Sub-node	-	A type other than main. Must match the input type you want to connect to.	Supply Data
Sub-node with sub-nodes	A type other than main	A type other than main. Must match the input type you want to connect to.	Supply Data

Built-in methods

n8n provides these methods to make it easier to perform common tasks in the LangChain Code node.

Method	Description
this.addInputData(inputName, data)	Populate the data of a specified non-main input. Useful for mocking data. inputName is the input connection type, and must be one of: ai_agent, ai_chain, ai_document, ai_embedding, ai_languageModel, ai_memory, ai_outputParser, ai_retriever, ai_textSplitter, ai_tool, ai_vectorRetriever, ai_vectorStore data contains the data you want to add. Refer to Data structure for information on the data structure expected by n8n.
this.addOutputData(outputName, data)	Populate the data of a specified non-main output. Useful for mocking data. outputName is the input connection type, and must be one of: ai_agent, ai_chain, ai_document, ai_embedding, ai_languageModel, ai_memory, ai_outputParser, ai_retriever, ai_textSplitter, ai_tool, ai_vectorRetriever, ai_vectorStore data contains the data you want to add. Refer to Data structure for information on the data structure expected by n8n.
this.getInputConnectionData(inputName, itemIndex, inputIndex?)	Get data from a specified non-main input. inputName is the input connection type, and must be one of: ai_agent, ai_chain, ai_document, ai_embedding, ai_languageModel, ai_memory, ai_outputParser, ai_retriever, ai_textSplitter, ai_tool, ai_vectorRetriever, ai_vectorStore itemIndex should always be 0 (this parameter will be used in upcoming functionality) Use inputIndex if there is more than one node connected to the specified input.
this.getInputData(inputIndex?, inputName?)	Get data from the main input.
this.getNode()	Get the current node.
this.getNodeOutputs()	Get the outputs of the current node.
this.getExecutionCancelSignal()	Use this to stop the execution of a function when the workflow stops. In most cases n8n handles this, but you may need to use it if building your own chains or agents. It replaces the Cancelling a running LLMChain code that you'd use if building a LangChain application normally.

Templates and examples

Browse LangChain Code node documentation integration templates or search all templates

Related resources

View n8n's Advanced AI documentation.