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PreconditionError

@rotorsoft/act-root

@rotorsoft/act-root / act/src / PreconditionError

Class: PreconditionError<TState, TEvents, TActions, TKey, TActor>

Defined in: libs/act/src/types/errors.ts:112

Thrown when a precondition from .requires([...]) refuses an action, with the message "<action> failed precondition: <description>".

Preconditions are what the caller must meet for the action to run now. They're checked after loading the current state and before the handler emits anything, so nothing is stored. Invariants (what must hold after every action) live in the state's schema instead; a broken one throws ValidationError.

Example​

Catching a refused action

import { PreconditionError } from "@rotorsoft/act";

try {
  await app.do("withdraw",
    { stream: "account-123", actor: { id: "user1", name: "Alice" } },
    { amount: 1000 }
  );
} catch (error) {
  if (error instanceof PreconditionError) {
    console.error("Action:", error.action);
    console.error("Reason:", error.description);
    console.error("Current state:", error.snapshot.state);
    console.error("Attempted payload:", error.payload);
  }
}

See​

Precondition for declaring them

Extends​

  • Error

Type Parameters​

TState​

TState extends Schema

State schema type

TEvents​

TEvents extends Schemas

Event schemas type

TActions​

TActions extends Schemas

Action schemas type

TKey​

TKey extends keyof TActions

Action name

TActor​

TActor extends Actor = Actor

Actor type extending base Actor

Constructors​

Constructor​

new PreconditionError<TState, TEvents, TActions, TKey, TActor>(action, payload, target, snapshot, description): PreconditionError<TState, TEvents, TActions, TKey, TActor>

Defined in: libs/act/src/types/errors.ts:130

Parameters​

action​

TKey

payload​

Readonly<TActions[TKey]>

target​

Target<TActor>

snapshot​

Snapshot<TState, TEvents>

description​

string

Returns​

PreconditionError<TState, TEvents, TActions, TKey, TActor>

Overrides​

Error.constructor

Properties​

action​

readonly action: TKey

Defined in: libs/act/src/types/errors.ts:120

The action that was attempted

cause?​

optional cause?: unknown

Defined in: node_modules/.pnpm/typescript@6.0.3/node_modules/typescript/lib/lib.es2022.error.d.ts:24

Inherited from​

Error.cause

description​

readonly description: string

Defined in: libs/act/src/types/errors.ts:128

Human-readable description of the precondition that refused the action

message​

message: string

Defined in: node_modules/.pnpm/typescript@6.0.3/node_modules/typescript/lib/lib.es5.d.ts:1075

Inherited from​

Error.message

name​

name: string

Defined in: node_modules/.pnpm/typescript@6.0.3/node_modules/typescript/lib/lib.es5.d.ts:1074

Inherited from​

Error.name

payload​

readonly payload: Readonly<TActions[TKey]>

Defined in: libs/act/src/types/errors.ts:122

The action payload that was provided

snapshot​

readonly snapshot: Snapshot<TState, TEvents>

Defined in: libs/act/src/types/errors.ts:126

The current state snapshot when the precondition was checked

stack?​

optional stack?: string

Defined in: node_modules/.pnpm/typescript@6.0.3/node_modules/typescript/lib/lib.es5.d.ts:1076

Inherited from​

Error.stack

target​

readonly target: Target<TActor>

Defined in: libs/act/src/types/errors.ts:124

The target stream and actor context

stackTraceLimit​

static stackTraceLimit: number

Defined in: node_modules/.pnpm/@types+node@22.20.5/node_modules/@types/node/globals.d.ts:68

The Error.stackTraceLimit property specifies the number of stack frames collected by a stack trace (whether generated by new Error().stack or Error.captureStackTrace(obj)).

The default value is 10 but may be set to any valid JavaScript number. Changes will affect any stack trace captured after the value has been changed.

If set to a non-number value, or set to a negative number, stack traces will not capture any frames.

Inherited from​

Error.stackTraceLimit

Methods​

captureStackTrace()​

static captureStackTrace(targetObject, constructorOpt?): void

Defined in: node_modules/.pnpm/@types+node@22.20.5/node_modules/@types/node/globals.d.ts:52

Creates a .stack property on targetObject, which when accessed returns a string representing the location in the code at which Error.captureStackTrace() was called.

const myObject = {};
Error.captureStackTrace(myObject);
myObject.stack;  // Similar to `new Error().stack`

The first line of the trace will be prefixed with ${myObject.name}: ${myObject.message}.

The optional constructorOpt argument accepts a function. If given, all frames above constructorOpt, including constructorOpt, will be omitted from the generated stack trace.

The constructorOpt argument is useful for hiding implementation details of error generation from the user. For instance:

function a() {
  b();
}

function b() {
  c();
}

function c() {
  // Create an error without stack trace to avoid calculating the stack trace twice.
  const { stackTraceLimit } = Error;
  Error.stackTraceLimit = 0;
  const error = new Error();
  Error.stackTraceLimit = stackTraceLimit;

  // Capture the stack trace above function b
  Error.captureStackTrace(error, b); // Neither function c, nor b is included in the stack trace
  throw error;
}

a();

Parameters​

targetObject​

object

constructorOpt?​

Function

Returns​

void

Inherited from​

Error.captureStackTrace

prepareStackTrace()​

static prepareStackTrace(err, stackTraces): any

Defined in: node_modules/.pnpm/@types+node@22.20.5/node_modules/@types/node/globals.d.ts:56

Parameters​

err​

Error

stackTraces​

CallSite[]

Returns​

any

See​

https://v8.dev/docs/stack-trace-api#customizing-stack-traces

Inherited from​

Error.prepareStackTrace