Key-Value Storage

Overview

This node provides a simple key-value storage mechanism using JSON files. It allows users to save a value under a specific key or read a value by its key from a file. This is useful for scenarios where you want to persist small amounts of data between workflow executions without setting up an external database or service.

Practical examples include:

• Caching API tokens or session data locally.
• Storing configuration flags or counters that need to be retained across runs.
• Saving temporary data generated in one part of a workflow to be used later.

Properties

Output

The node outputs a single JSON object with the following structure depending on the operation:

• Save Operation:

  {
    "<key>": {
      "value": "<saved_value>",
      "operation": "save",
      "status": "Saved"
    }
  }
  

  This confirms the key and value were saved successfully.

• Read Operation:

  {
    "key": "<key>",
    "value": "<retrieved_value_or_null>",
    "operation": "read"
  }
  

  Returns the value associated with the key, or null if the key does not exist.

No binary data output is produced by this node.

Dependencies

• Uses Node.js built-in fs (filesystem) and path modules to read/write JSON files.
• Stores data in a subdirectory named data relative to the node's source code directory.
• No external services or API keys are required.

Troubleshooting

• File Access Issues: If the node cannot create or write to the data directory or JSON file, ensure the n8n process has appropriate filesystem permissions.
• Corrupted JSON File: Manual edits or concurrent writes might corrupt the JSON file, causing parse errors. Deleting or fixing the file may resolve this.
• Missing Key on Read: Reading a non-existent key returns null. Confirm the key was saved previously.
• Invalid Input: Ensure all required properties (File, Key, and for save operation, Value) are provided; otherwise, the node will error out.

Links and References

• Node.js fs module documentation
• Node.js path module documentation