Interface

CustomValidatorConfig

@ng-forge/dynamic-forms

Custom validator configuration using Angular's public FieldContext API. Returns ValidationError | ValidationError[] | null synchronously.

Three authoring forms (mutually exclusive at runtime, not enforced by TypeScript): 1. Registered function: { type: 'custom', functionName: 'myValidator' } 2. Inline function (code-only): { type: 'custom', fn: (ctx) => ... } 3. Expression-based: { type: 'custom', expression: 'fieldValue === formValue.password', kind: 'passwordMismatch' }

Unlike AsyncValidatorConfig and FunctionHttpValidatorConfig (strict fn ↔ functionName XOR via discriminated unions), this surface keeps a permissive interface — the historical expression-vs-functionName split was already runtime-checked, so adding fn follows the same precedent. The runtime resolver picks one source and warns if fn and functionName are both set; inline fn wins.

fn is NOT JSON-serializable — for code-only configs. For configs loaded from JSON / OpenAPI / databases, prefer functionName to reference a function registered in customFnConfig.validators.

Signature

interface CustomValidatorConfig
  extends BaseValidatorConfig

Properties

Name	Type	Description
`type`	`"custom"`	Validator type identifier
`functionName` ?	`string \| undefined`	Name of registered validator function (function-based pattern)
`fn` ?	`CustomValidator \| undefined`	Inline custom validator (code-only authoring). Mutually exclusive with `functionName`. NOT JSON-serializable.
`params` ?	`Record<string, unknown> \| undefined`	Optional parameters to pass to validator function
`expression` ?	`string \| undefined`	JavaScript expression to evaluate (expression-based pattern)
`kind` ?	`string \| undefined`	Error kind for expression-based validators - links to validationMessages
`errorParams` ?	`Record<string, string> \| undefined`	Parameters to include in error object for message interpolation (expression-based pattern) Map of parameter names to expressions that will be evaluated in the same context as the validation expression

packages/dynamic-forms/src/lib/models/validation/validator-config.ts:48