Recipe: add a quality rule

Time: 2 minutes · Audience: anyone with an existing contract

Problem

You have a working contract but no enforcement against silent data issues — null customer_id, stale freshness, duplicate primary keys.

Solution

Add a dq.rules block under the expose.contract. Only id, type, and severity are required — most rules also add selector + threshold + operator (a freshness rule swaps those for a single window). The four below cover ~80 % of real-world cases.

Add this to exposes[].contract

exposes:
  - exposeId: customer_orders
    contract:
      schema:
        - name: order_id
          type: STRING
          required: true
        - name: customer_id
          type: STRING
          required: true
        - name: total
          type: NUMERIC
          required: true
        - name: order_ts
          type: TIMESTAMP
          required: true

      dq:
        rules:
          # 1. Block deploys with null customer_id (any null = error)
          - id: customer_id_complete
            type: completeness
            selector: customer_id
            threshold: 1.0
            operator: ">="
            severity: error

          # 2. Block on duplicate order_id (must be unique)
          - id: order_id_unique
            type: uniqueness
            selector: order_id
            threshold: 1.0
            operator: ">="
            severity: error

          # 3. Warn (don't block) if data is more than 1 hour old
          - id: orders_freshness
            type: freshness
            window: PT1H
            severity: warn

          # 4. Block if total has any negative values (every row must satisfy total >= 0)
          - id: total_non_negative
            type: accuracy
            selector: total
            threshold: 0.0
            operator: ">="
            severity: error

Test it

fluid validate contract.fluid.yaml      # ← passes if rule syntax is well-formed
fluid test contract.fluid.yaml          # ← runs the rules against live data
fluid apply contract.fluid.yaml --yes   # ← aborts on any rule with severity: error

Severity levels

SeverityBehavior
errorfluid apply aborts. Hard guarantee.
warnDeploy proceeds; warning emitted to stdout + test report.
infoRecorded only. Useful for tracking metrics over time.

See also