How can I retrieve and filter file modification dates in n8n workflows?

Based on the documentation, the Read/Write Files from Disk node only returns file-related metadata like name, directory, size, extension, and MIME type. It does not include file system attributes such as the modified date.

If you need to filter the files by their modified date (for example, only processing files updated in the past day), you'll need a workaround. Here are some approaches:

Use an Execute Command Node

You can run a shell command (like Linux’s stat) to grab the modified date and then pass that data into your workflow for filtering. For example, you might run:

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stat -c "%Y %n" /data/syncthing/LogSeq/journals/*

This command returns the modification timestamp and filename for each file. You can then parse this in your workflow and compare timestamps to determine whether the file was updated in the past day.

Use a Custom Code Node

Alternatively, you could use an Execute Code (JavaScript) node that leverages Node.js libraries (when self-hosting) to read the file system metadata. This way, you can use the built-in fs module to get the stats, then use that metadata for filtering. For example:

JAVASCRIPTCopied
const fs = require('fs');
const path = '/data/syncthing/LogSeq/journals/2023_01_10.md'; // modify accordingly

fs.stat(path, (err, stats) => {
  if (err) {
    throw err;
  }
  // stats.mtime contains the last modified date
  console.log("Modified Time:", stats.mtime);
  // Further logic to filter by modification time here
});
return items;

Summary

Because the Read/Write Files from Disk node does not provide modification dates, you’ll need to either:

• Use an Execute Command node to run a shell command (like stat) to extract file metadata, or
• Use a custom code node (e.g., Execute Code) to call Node.js functions such as fs.stat and then filter files based on modification date.

These approaches allow you to decide which files updated within the past day should trigger the subsequent steps in your workflow.

Remember that since your n8n instance is self-hosted, you'll have the flexibility to integrate these workarounds.

Based on your description, the problem is that the Read/Write Files from Disk node only returns basic file information (like name, size, type, etc.) and omits metadata such as the file modified date. In your case, you need to filter files based on whether they were updated in the past day, but without using the “When File Changed” trigger since the files update frequently.

Why This Happens

The built‐in file node is designed to access file content and a minimal set of properties. It does not include the modified date (or other file system metadata) that you need for your filtering logic.

Potential Workarounds

1. Use an Execute Command Node (or similar) to Retrieve Metadata:

   Since you’re running n8n on Docker (self‑hosted on Synology), you can use an Execute Command node to run a shell command (such as ls or stat) that returns the modified date. For example, on Linux you might run a command like:

   BASHCopied
   stat -c '%Y %n' /data/syncthing/LogSeq/journals/2023_01_10.md

   This command returns the file’s last modification time (in epoch seconds) along with the filename. You can then process that output in your workflow.

2. Chain with a Date & Time Node:

   Once you have the modified date from the Execute Command node, use a Date & Time node to convert and compare the modification timestamp with your “past day” threshold. This lets you only pass files updated within the desired timeframe.

3. Custom Script or Node:

   If you need a more robust solution, consider writing a custom script or even an n8n custom node that reads the file’s metadata and outputs the additional properties you require.

Example Workflow Snippet

Below is an example snippet to illustrate using the Execute Command node to read the modification time, then parsing it for further filtering:

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{
  "nodes": [
    {
      "parameters": {},
      "id": "manual-trigger",
      "name": "When clicking 'Test workflow'",
      "type": "n8n-nodes-base.manualTrigger",
      "typeVersion": 1,
      "position": [
        -640,
        0
      ]
    },
    {
      "parameters": {
        "command": "stat -c '%Y %n' {{ $json.filePath }}"
      },
      "id": "execute-command",
      "name": "Get File Modified Date",
      "type": "n8n-nodes-base.executeCommand",
      "typeVersion": 1,
      "position": [
        -420,
        100
      ]
    },
    {
      "parameters": {
        "date": "={{ $json.modifiedEpoch }}",
        "mode": "add",
        "timeAmount": 1,
        "timeUnit": "days",
        "outputFieldName": "oneDayAgo"
      },
      "id": "date-time",
      "name": "Calculate Threshold Date",
      "type": "n8n-nodes-base.dateTime",
      "typeVersion": 2,
      "position": [
        -200,
        100
      ]
    },
    {
      "parameters": {
        "conditions": {
          "conditions": [
            {
              "leftValue": "={{ $json.modifiedEpoch }}",
              "operator": "larger",
              "rightValue": "={{ $json.oneDayAgo }}"
            }
          ]
        }
      },
      "id": "if-node",
      "name": "Filter Files (Modified in Last Day)",
      "type": "n8n-nodes-base.if",
      "typeVersion": 2,
      "position": [
        0,
        100
      ]
    }
  ],
  "connections": {
    "When clicking 'Test workflow'": {
      "main": [
        [
          {
            "node": "Get File Modified Date",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Get File Modified Date": {
      "main": [
        [
          {
            "node": "Calculate Threshold Date",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Calculate Threshold Date": {
      "main": [
        [
          {
            "node": "Filter Files (Modified in Last Day)",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}

Note: In the above snippet, replace {{ $json.filePath }} with the actual file path you are checking, and adjust the command and parsing logic to transform the output from the Execute Command node into a JSON format with a property like modifiedEpoch.

Summary

• The Read/Write Files from Disk node does not supply modified date metadata.
• You can execute a command (like stat) with an Execute Command node to extract the modified date.
• Follow up with a Date & Time node to calculate your comparison threshold and an If node to filter files updated within the past day.

This workaround gives you the additional metadata required for your workflow without relying on a file change trigger.