@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.

Install

This package isn't on npm yet. Install from the reso-tools monorepo on GitHub:

git clone https://github.com/RESOStandards/reso-tools.git
cd reso-tools/reso-validation
npm install

This package has no sibling dependencies — npm install just runs. To bootstrap every package at once, run npm run bootstrap from the repo root instead.

To consume the SDK from another project, link it locally with npm link or use a file: dependency.

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.