The `||` operator doesn't work in the Window Buffer Memory node.

[xhzkp]

Bug Description

I want to make the Window Buffer Memory node compatible with both the Webhook and Chat Message triggers, so I tried to use the following expression to achieve this.

{{ $('Webhook').first().json?.sessionId || $('When chat message received').first().json.sessionId }}

However, it doesn't work. This type of expression works in other nodes.

BUG4.mp4

Workflow config code:

{
  "nodes": [
    {
      "parameters": {
        "public": true,
        "initialMessages": "ChatGPT",
        "options": {
          "allowFileUploads": true,
          "allowedFilesMimeTypes": "txt,pdf",
          "subtitle": "",
          "title": "Hi there! 👋"
        }
      },
      "type": "@n8n/n8n-nodes-langchain.chatTrigger",
      "typeVersion": 1.1,
      "position": [
        -120,
        180
      ],
      "id": "740a0e1a-c655-4d99-863c-0e8569820fb5",
      "name": "When chat message received",
      "webhookId": "a8dbf527-12af-4d82-a7a7-ddbd69e6265b"
    },
    {
      "parameters": {
        "promptType": "define",
        "text": "=sessionId: {{ $json.query?.sessionId || $json.sessionId }}\nchatInput: {{ $json.query?.chatInput || $json.chatInput }}\n",
        "options": {}
      },
      "type": "@n8n/n8n-nodes-langchain.agent",
      "typeVersion": 1.7,
      "position": [
        240,
        120
      ],
      "id": "0fa9f0b1-539d-4dd3-b2f4-c86f0547c40d",
      "name": "AI Agent"
    },
    {
      "parameters": {
        "options": {
          "baseURL": "https://api.chatanywhere.org/v1"
        }
      },
      "type": "@n8n/n8n-nodes-langchain.lmChatOpenAi",
      "typeVersion": 1,
      "position": [
        200,
        340
      ],
      "id": "41df6a07-b5bb-4b49-8f44-3cb6bb7e935f",
      "name": "OpenAI Chat Model",
      "credentials": {
        "openAiApi": {
          "id": "oYt1X4B1EySK0Ho4",
          "name": "OpenAi Free"
        }
      }
    },
    {
      "parameters": {
        "path": "ZP",
        "responseMode": "responseNode",
        "options": {}
      },
      "type": "n8n-nodes-base.webhook",
      "typeVersion": 2,
      "position": [
        -120,
        20
      ],
      "id": "be97f8d6-0f80-4d6a-ad51-0db8baa40946",
      "name": "Webhook",
      "webhookId": "323dbfae-6242-4a36-8501-ad9be790aba0"
    },
    {
      "parameters": {
        "options": {}
      },
      "type": "n8n-nodes-base.respondToWebhook",
      "typeVersion": 1.1,
      "position": [
        680,
        20
      ],
      "id": "9e9e770c-8189-43f6-a78d-47dbfa4951b5",
      "name": "Respond to Webhook"
    },
    {
      "parameters": {
        "sessionIdType": "customKey",
        "sessionKey": "={{ $('Webhook').first().json?.sessionId || $('When chat message received').first().json.sessionId }}"
      },
      "type": "@n8n/n8n-nodes-langchain.memoryBufferWindow",
      "typeVersion": 1.3,
      "position": [
        340,
        340
      ],
      "id": "459564ff-871f-4acc-8edb-f10cc0fff173",
      "name": "Window Buffer Memory"
    }
  ],
  "connections": {
    "When chat message received": {
      "main": [
        [
          {
            "node": "AI Agent",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "AI Agent": {
      "main": [
        [
          {
            "node": "Respond to Webhook",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "OpenAI Chat Model": {
      "ai_languageModel": [
        [
          {
            "node": "AI Agent",
            "type": "ai_languageModel",
            "index": 0
          }
        ]
      ]
    },
    "Webhook": {
      "main": [
        [
          {
            "node": "AI Agent",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Window Buffer Memory": {
      "ai_memory": [
        [
          {
            "node": "AI Agent",
            "type": "ai_memory",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}

To Reproduce

1. copy config
2. run

Expected behavior

support ||

Operating System

self-hosted n8n on a Windows 10

n8n Version

1.71

Node.js Version

20.18.0

Database

SQLite (default)

Execution mode

main (default)

[Joffcom]

Hey @xhzkp,

We have created an internal ticket to look into this which we will be tracking as "GHC-574"

[OlegIvaniv]

Hi @xhzkp,

you can accomplish this behaviour by checking if the Webhook node was executed first. So something like this:

{{ $('Webhook').isExecuted ? $('Webhook')?.first()?.json?.sessionId : $('When chat message received').first().json.sessionId }}

[xhzkp]

@OlegIvaniv
Thank you for the help. An error occurred while testing the webhook.

Bug2.mp4

[OlegIvaniv]

@OlegIvaniv Thank you for the help. An error occurred while testing the webhook.

Bug2.mp4

Ah, that's because you're sending the webhook parameters in query, so you need to access them as such. Here's updated expression: {{ $('Webhook').isExecuted ? $('Webhook').item.json.query?.sessionld : $('When chat message received').json.sessionId }}

[xhzkp]

@OlegIvaniv Thank you for the help. An error occurred while testing the webhook.
Bug2.mp4

Ah, that's because you're sending the webhook parameters in query, so you need to access them as such. Here's updated expression: {{ $('Webhook').isExecuted ? $('Webhook').item.json.query?.sessionld : $('When chat message received').json.sessionId }}

Thank you for your help! The code above works perfectly.
Will the || expression be supported in the future? It's very concise.

[OlegIvaniv]

@OlegIvaniv Thank you for the help. An error occurred while testing the webhook.
Bug2.mp4

Ah, that's because you're sending the webhook parameters in query, so you need to access them as such. Here's updated expression: {{ $('Webhook').isExecuted ? $('Webhook').item.json.query?.sessionld : $('When chat message received').json.sessionId }}

Thank you for your help! The code above works perfectly. Will the || expression be supported in the future? It's very concise.

Hey @xhzkp, just realized that this actually works, but you need to access .json directly, not .item.json. So: {{ $('Webhook').json?.sessionId || $('When chat message received').json.sessionId }}.

[xhzkp]

@OlegIvaniv Thank you for the help. An error occurred while testing the webhook.
Bug2.mp4

Ah, that's because you're sending the webhook parameters in query, so you need to access them as such. Here's updated expression: {{ $('Webhook').isExecuted ? $('Webhook').item.json.query?.sessionld : $('When chat message received').json.sessionId }}

Thank you for your help! The code above works perfectly. Will the || expression be supported in the future? It's very concise.

Hey @xhzkp, just realized that this actually works, but you need to access .json directly, not .item.json. So: {{ $('Webhook').json?.sessionId || $('When chat message received').json.sessionId }}.

This causes an error when using a webhook.

[OlegIvaniv]

@OlegIvaniv Thank you for the help. An error occurred while testing the webhook.
Bug2.mp4

Ah, that's because you're sending the webhook parameters in query, so you need to access them as such. Here's updated expression: {{ $('Webhook').isExecuted ? $('Webhook').item.json.query?.sessionld : $('When chat message received').json.sessionId }}

Thank you for your help! The code above works perfectly. Will the || expression be supported in the future? It's very concise.

Hey @xhzkp, just realized that this actually works, but you need to access .json directly, not .item.json. So: {{ $('Webhook').json?.sessionId || $('When chat message received').json.sessionId }}.

This causes an error when using a webhook.

A simples expression would be: {{ $json.query?.sessionId || $json.sessionId }} that should work for both webhook and chat. Here's reference WF:
My_workflow_202.json