n8n-nodes-schema-guard

Schema Guard — A data-contract enforcer for n8n.
Validates incoming JSON items against a schema, auto-fills defaults, renames fields, and routes invalid records — bringing typed pipelines to n8n.

Why?

Workflows break silently when upstream JSON shapes change.
Schema Guard catches those changes at runtime, preventing bad data from cascading through your pipeline.

Features

| Capability | Description | | --- | --- | | Validate | Check every item against a JSON Schema (draft-07 / 2020-12) | | Auto-Generate Schema | Infer the schema from the first incoming item automatically | | Auto-Fill Defaults | Missing fields are populated from schema default values or custom defaults | | Rename Fields | Map old field names to new ones before validation | | Route / Drop / Error | Choose what happens to invalid items — route them to a second output, drop them silently, or halt the workflow | | Structured Errors | Invalid items carry _schemaErrors with detailed diagnostics |

Installation

In n8n (Community Nodes)

1. Go to Settings → Community Nodes
2. Enter n8n-nodes-schema-guard
3. Click Install

Manual / npm

npm install n8n-nodes-schema-guard

Then restart n8n.

Usage

1. Validate Mode

Paste a JSON Schema into the JSON Schema field. Every incoming item is validated against it.

{
  "type": "object",
  "properties": {
    "email": { "type": "string", "format": "email" },
    "age":   { "type": "integer", "minimum": 0 },
    "role":  { "type": "string", "default": "viewer" }
  },
  "required": ["email"]
}

2. Auto-Generate Schema Mode

No schema? No problem. Schema Guard inspects the first item and derives a schema from it, then validates all items against that shape.

Options

| Option | Default | Description | | --- | --- | --- | | Auto-Fill Defaults | true | Fills missing fields from schema default values | | Custom Defaults | {} | Extra field → value pairs applied before validation | | Rename Fields | {} | {"old_name": "newName"} mapping applied before validation | | Include Error Details | true | Attaches _schemaErrors array to invalid items | | Additional Properties | true | Whether to allow fields not in the schema |

Outputs

| Output | Contents | | --- | --- | | Valid (top) | Items that passed validation | | Invalid (bottom) | Items that failed (when On Invalid = "Route to Second Output") |

On Invalid Item

• Route to Second Output — invalid items are sent to the second output with error metadata
• Drop Silently — invalid items are removed entirely
• Stop Workflow With Error — throws an error, halting execution

Example Workflow

HTTP Request → Schema Guard → IF → Database
                    ↓ (invalid)
               Slack Notification

Development

git clone https://github.com/ammaralshuaibi/n8n-nodes-schema-guard.git
cd n8n-nodes-schema-guard
npm install
npm run build

License

MIT