index.d.ts

type onFailure = 'ignore' | 'setNull';

export interface PropertyCheckParams {
  type?: any;
  arrayType?: any;
  required?: boolean;
  nullable?: boolean;
  onFailure?: onFailure;
  customValidator?: (input: any) => boolean;
}

export declare enum ValidationErrorType {
  NullValue = 'null',
  MissingField = 'missing',
  InvalidType = 'invalid',
}

export class ValidationError extends Error {
  public readonly field: string | undefined;
  public readonly errorType: ValidationErrorType;
}

export function TypesCheck(
  target: any,
  propertyKey: string,
  descriptor: TypedPropertyDescriptor<any>
): any;
export function TypeCheck(type: any): any;
export function PropertyCheck(params?: PropertyCheckParams): any;
export function validate<T>(input: any, expectedType: new () => T): T;
export function validate<T extends ArrayConstructor, U>(
  input: any,
  expectedType: T,
  arrayType: new () => U
): U[];