@reso-standards/validation

Isomorphic TypeScript validation library for RESO Data Dictionary records. Validates field types, lengths, and ranges against metadata, plus resource-specific business rules with cross-field constraints. Zero external dependencies.

User Guide – a task-oriented walkthrough with realistic examples.

Usage

import { validateRecord, validateBusinessRules, getBusinessRules } from '@reso-standards/validation';
import type { ResoField, ValidationFailure } from '@reso-standards/validation';

// Validate a record against field metadata
const failures = validateRecord(record, fields);

// Validate resource-specific business rules
const ruleFailures = validateBusinessRules('Property', record);

// Get the rule definitions for a resource
const rules = getBusinessRules('Property');

API

validateRecord(body, fields): ValidationFailure[]

Validates a record payload against RESO field metadata. Checks:

• Unknown fields – fields not in metadata
• Type mismatches – Edm.String, Edm.Boolean, Edm.Int32, Edm.Decimal, Edm.Date, Edm.DateTimeOffset, etc.
• Negative numerics – rejects negative values for numeric types
• MaxLength – strings exceeding field.maxLength
• Integer enforcement – Int types must be whole numbers
• Collection fields – must be arrays
• Enum fields – must be string or number
• Business rules – delegates to validateBusinessRules() for range/relationship checks

Null, undefined, and empty string values are silently skipped unless the field is required. Fields starting with @ (OData annotations) are ignored.

validateBusinessRules(resourceName, body): ValidationFailure[]

Validates resource-specific constraints:

Property:

• Required: City, StateOrProvince, PostalCode, Country
• Price fields (> 0 to $1B): ListPrice, OriginalListPrice, PreviousListPrice, ClosePrice, ListPriceLow
• Room counts (0 to 100): BedroomsTotal, BathroomsFull, BathroomsHalf, etc.
• Expense/fee/amount fields ($0 to $10K): matched via fieldPattern regex /(?:Expense|Amount|Fee\d?)$/
• Latitude and Longitude are exempt from the non-negative rule (negative coordinates are valid)
• Cross-field: BathroomsTotalInteger = sum(BathroomsFull + BathroomsHalf + ...)

Member: Required MemberCity, MemberStateOrProvince, MemberPostalCode, MemberCountry

Office: Required OfficeCity, OfficeStateOrProvince, OfficePostalCode, OfficeCountry

getBusinessRules(resourceName): FieldRule[]

Returns the per-field constraint definitions for a resource.

Type Helpers

• isEnumType(type) – true if type is an enum reference (not a primitive Edm type)
• isNumericEdmType(type) – true for Edm.Decimal, Edm.Int32, Edm.Double, etc.
• isIntegerEdmType(type) – true for Edm.Int16, Edm.Int32, Edm.Int64, Edm.Byte

Types

interface ValidationFailure {
  readonly field: string;
  readonly reason: string;
}

interface FieldRule {
  readonly fieldName: string;
  readonly fieldPattern?: RegExp;  // regex alternative to fieldName for matching multiple fields
  readonly required?: boolean;
  readonly min?: number;
  readonly max?: number;
  readonly message?: string;
}

interface CrossFieldRule {
  readonly name: string;
  readonly validate: (body: Record<string, unknown>) => ValidationFailure | null;
}

Integration

Used by both the reference server (request body validation on POST/PATCH) and the React UI (client-side form validation). Also used by @reso-standards/certification for payload validation in compliance testing.

License

See LICENSE in the repository root.