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What is a Fact Definition?

A Fact Definition declares an input variable that your rules can reference in conditions and actions. Think of it like a function parameter — you define the name, type, and whether it’s required before writing the logic. Facts are tenant-wide: once defined, they’re available across all policy groups and versions.

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System Facts

Every tenant has 7 pre-registered system facts available immediately after account creation. These cannot be deleted:
KeyTypeRequiredDescription
user_idSTRING✅User identifier
payment_amountNUMBER✅Payment amount
phone_numberSTRINGPhone number
emailSTRINGEmail address
device_tokenSTRINGDevice token (for push notifications)
user_tagsLIST_STRINGUser tags
total_pointNUMBERCurrent point balance
System facts can be used in conditions and actions immediately — no registration needed.

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Custom Facts

Any input variable beyond the 7 system facts must be registered before use. For example, customer_tier, order_region, or product_category are custom facts. 
lexq facts create --key customer_tier --name "Customer Tier" --type STRING
lexq facts create --key order_region --name "Order Region" --type STRING --required

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Supported Types

TypeJSONExample Value
STRING"string""VIP"
NUMBERnumber100000
BOOLEANtrue / falsetrue
LIST_STRING["a", "b"]["KR", "US"]
LIST_NUMBER[1, 2][10000, 20000]

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Naming Conventions

Fact keys must follow snake_case naming. Keys are case-sensitive.
  • ✅ payment_amount, customer_tier, user_region
  • ❌ paymentAmount, Payment-Amount, PAYMENT AMOUNT

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Required vs Optional Facts

  • Required facts must be present in every execution request. If missing, the engine returns an INVALID_INPUT error.
  • Optional facts can be omitted. Rules referencing missing optional facts evaluate their conditions as false (no match).

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Managing Facts

Facts are managed in the Console under Management → Fact Definitions, or via the CLI: 
lexq facts list
lexq facts create --key order_total --name "Order Total" --type NUMBER --required
lexq facts update --id <factId> --name "Total Order Amount"
lexq facts delete --id <factId>
Use lexq analytics requirements (CLI) or the Engine API’s GET /groups/{groupId}/requirements endpoint to see exactly which facts a deployed version needs.
Deleting a fact does not automatically remove it from existing rules. Rules referencing a deleted fact will evaluate that condition as false. Always review rule dependencies before deleting.

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Next Steps

Policy Rules

Use facts in rule conditions and actions.

Policy Execution

See how facts are passed during execution.