n8n-nodes-rule-evaluator

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Put your workflow rules in one node -- one place to edit policies.

n8n-nodes-rule-evaluator is an n8n community node package for deterministic business-rule decisions.

For each input item, it evaluates rule conditions, resolves conflicts using a fixed priority strategy (Business Rules) or a table hit policy (Decision Table), and routes the item to the resolved outcome.

Before and after

Before -- policies scattered across the canvas:

[Trigger] -> [IF ...] -> [IF ...] -> [Switch] -> ...
                |            |
                v            v
             [IF ...]    [Merge] -> ...

After -- rules consolidated into one node:

[Trigger] -> [Business Rules] -> (Allow / Escalate / Deny / ...)

Same item, same inputs; one place to edit when policies change.

In 15 seconds

1. Drop Business Rules or Decision Table on the canvas.
2. Add rules/cases with the native n8n condition UI.
3. Connect outputs -- routing is built in.

What you get

• One node for many rules -- all policies in one place.
• Built-in routing -- no extra Switch for standard outcomes.
• Two decision patterns:
  • Business Rules (enum outcomes with a priority ladder)
  • Decision Table (switchless table routing with hit policies)
• Legacy compatibility -- Rule Enricher for existing workflows.

Nodes in this package

• Business Rules: evaluate independent rules per item, resolve conflicts with a fixed priority ladder, and route to the resolved outcome.
• Decision Table: switchless, table-based routing with user-defined string decisions and four hit policies: Unique, First, Unanimous, Collect.
• Rule Enricher: legacy helper that writes the decision to a field (default _decision); you add a Switch for routing.

Which node should I use?

| | Business Rules | Decision Table | | -------- | ---------------------------------------------- | ---------------------------------------------- | | Shape | Independent rules | Table rows (cases) | | Overlap | Several rules can match | Cases are usually mutually exclusive | | Outcomes | allow, escalate, silent, deny, error | Your own string decisions | | Routing | Output routing by resolved enum outcome | Switchless dynamic outputs based on hit policy |

Not sure? Start with Business Rules.

Business Rules

Use when you have many independent checks (several can be true at once) and you need one final decision.

Decision priority (low -> high):

allow < escalate < silent < deny < error

If a rule condition fails to evaluate, the outcome is error.

Decision Table

Use when your logic is case-based: each case combines several conditions (AND) and maps to a string decision.

Decision Table is switchless: it exposes dynamic outputs depending on Hit Policy.

Hit policies (all available in 1.2.x):

• Unique (default): no match -> default, one match -> case decision, 2+ matches -> runtime error
• First: first matching case wins (top-to-bottom row order)
• Unanimous: all matched cases must agree (otherwise runtime error)
• Collect: gathers all matched case decisions into an array and routes to a single decision output

Quick Start

Check out our Workflow Examples to import these directly into your n8n canvas.

Try Business Rules

Build a chat gate with built-in routing -- no IF chain before every reply.

1. Add When chat message received, then Business Rules.
2. Add Rule 1: risk_score >= 80 -> deny
3. Add Rule 2: is_suspicious = true -> escalate
4. Set Default Decision to allow
5. Wire outputs:

• Allow -> Answer (Send Message)
• Escalate -> Request Approval (Send and Wait) -> human approval
• Deny -> Not Permitted (Send Message)

6. Run with { "risk_score": 50, "is_suspicious": true } -> item exits Escalate (human review).

[When chat message received] -> [Business Rules] -- Allow -----> [Answer]
                                    |-- Escalate -> [Request Approval] -> ...
                                    +-- Deny -----> [Not Permitted]

Try Decision Table

1. Add the Decision Table node.
2. Add Case 1: status = "pending" AND days_open > 7 -> escalate
3. Add Case 2: status = "pending" -> wait
4. Set Default Decision to closed
5. Set Hit Policy to First (top row wins when several cases match).
6. Connect outputs and run with { "status": "pending", "days_open": 10 } -> item exits as escalate.

Both cases match, but First picks Case 1 because it is above Case 2. No code. Native n8n condition UI.

For overlapping cases where order matters, use First. For conflict detection, use Unanimous.

Reference

Installation

n8n UI

1. Settings -> Community Nodes -> Install
2. Package name: n8n-nodes-rule-evaluator
3. Restart n8n if prompted

npm / Docker

npm install n8n-nodes-rule-evaluator

Restart n8n after install.

Business Rules parameters

| Parameter | Description | | --------------------- | ------------------------------------------------------------------------ | | Default Decision | One of: allow, escalate, silent, deny, error. Default: deny. | | Rules | Fixed collection. Each rule: one IF-style condition and a Decision. | | Output Field Name | Field written to JSON. Default: _decision. | | Include Matched Rules | Adds matched_rules for debugging (ruleIndex and decision). |

Decision Table parameters

| Parameter | Description | | -------------------- | ---------------------------------------------------------------------- | | Default Decision | Used when no case matches. | | Cases | Each case: multiple conditions (AND) and a custom string Decision. | | Hit Policy | Unique / First / Unanimous / Collect. Default: Unique. | | Output Field Name | Default: _decision. | | Include Matched Case | Debug: which case matched. |

Output type for {Output Field Name}:

• Unique / First / Unanimous: string
• Collect: string[] (array of matched decisions in case order)

Rule Enricher (legacy)

Deprecated but supported for existing workflows.

It writes the resolved decision to the configured output field (default _decision); you add a Switch node for routing.

New workflows should use Business Rules.

Output example

{
  "message": "Can you help with my order?",
  "is_suspicious": true,
  "risk_score": 50,
  "_decision": "escalate"
}

Compatibility

• Requires n8n >= 1.0.0 (uses the modern Condition UI).
• Any n8n instance with community nodes enabled. No credentials are required.
• Package scope for 1.2.x: Decision Table, Business Rules, and Rule Enricher (legacy).
• One output item per input item; Business Rules routes each item to exactly one dynamic output.

Troubleshooting

• Unexpected error: check expressions and mapped fields; unevaluable conditions become error.
• No match: verify input fields and Default Decision.
• Debug visibility: enable Include Matched Rules / Include Matched Case.

Testing and development

npm test
npm run verify