medusajs/medusa · error · MedusaError

Rule value must be an array for in/nin operators

Error message

Rule value must be an array for in/nin operators

What it means

For the in and nin operators the rule value must be an array. Passing a scalar (string/number/bool) throws INVALID_DATA.

Source

Thrown at packages/modules/fulfillment/src/utils/utils.ts:131

  if (!isString(rule.operator)) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      "Rule operator must be a string"
    )
  }

  if (!availableOperators.includes(rule.operator as RuleOperator)) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      `Rule operator ${
        rule.operator
      } is not supported. Must be one of ${availableOperators.join(", ")}`
    )
  }

  if (rule.operator === RuleOperator.IN || rule.operator === RuleOperator.NIN) {
    if (!Array.isArray(rule.value)) {
      throw new MedusaError(
        MedusaError.Types.INVALID_DATA,
        "Rule value must be an array for in/nin operators"
      )
    }
  } else {
    if (Array.isArray(rule.value) || isObject(rule.value)) {
      throw new MedusaError(
        MedusaError.Types.INVALID_DATA,
        `Rule value must be a string, bool, number value for the selected operator ${rule.operator}`
      )
    }
  }

  return true
}

export function normalizeRulesValue<T extends Partial<Rule>>(rules: T[]): void {
  rules.forEach((rule: any) => {

View on GitHub (pinned to 5e06e544a2)

Solutions

1. Wrap the value in an array for in/nin rules
2. Use eq/neq for single scalar comparisons

Example fix

// before
rules: [{ attribute: 'iso', operator: 'in', value: 'dk' }]
// after
rules: [{ attribute: 'iso', operator: 'in', value: ['dk', 'se'] }]

if ((rule.operator === 'in' || rule.operator === 'nin') && !Array.isArray(rule.value)) rule.value = [rule.value]

const isArrayValueForInRule = (r: any): boolean => !(r.operator === 'in' || r.operator === 'nin') || Array.isArray(r.value)

When it happens

Trigger: rules: [{ attribute: 'iso', operator: 'in', value: 'dk' }] instead of value: ['dk'].

Common situations: Copying a single-value eq rule and changing only the operator; form inputs sending a single string where the API expects a list.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Rule must have an attribute, an operator and a value
• Rule operator ${rule.operator} is not supported. Must be one
• Rule value must be a string, bool, number value for the sele
• Invalid rule attribute - ${ruleAttributeId}
• The following shipping options do not exist: ${Array.from(mi

AI-assisted analysis of medusajs/medusa@5e06e544a2 (2026-08-27). Data as JSON: /api/errors/64ad46d0f5912058. Report an issue: GitHub.