@middy/appconfig/index.d.ts

AppConfig middleware for the middy framework

// Copyright 2017 - 2026 will Farrell, Luciano Mammino, and Middy contributors.
// SPDX-License-Identifier: MIT
import type {
	AppConfigDataClient,
	AppConfigDataClientConfig,
	StartConfigurationSessionRequest,
} from "@aws-sdk/client-appconfigdata";
import type middy from "@middy/core";
import type { Options as MiddyOptions } from "@middy/util";
import type { Context as LambdaContext } from "aws-lambda";

export type ParamType<T> = StartConfigurationSessionRequest & {
	__returnType?: T;
};
export declare function appConfigParam<T>(
	name: StartConfigurationSessionRequest,
): ParamType<T>;

export interface AppConfigOptions<AwsAppConfigClient = AppConfigDataClient>
	extends Omit<
		MiddyOptions<AwsAppConfigClient, AppConfigDataClientConfig>,
		"fetchData"
	> {
	fetchData?: {
		[key: string]: StartConfigurationSessionRequest | ParamType<unknown>;
	};
}

export type Context<TOptions extends AppConfigOptions | undefined> =
	TOptions extends { setToContext: true }
		? TOptions extends { fetchData: infer TFetchData }
			? LambdaContext & {
					[Key in keyof TFetchData]: TFetchData[Key] extends ParamType<infer T>
						? T
						: unknown;
				}
			: never
		: LambdaContext;

export type Internal<TOptions extends AppConfigOptions | undefined> =
	TOptions extends AppConfigOptions
		? TOptions extends { fetchData: infer TFetchData }
			? {
					[Key in keyof TFetchData]: TFetchData[Key] extends ParamType<infer T>
						? T
						: unknown;
				}
			: {}
		: {};

declare function appConfigMiddleware<TOptions extends AppConfigOptions>(
	options?: TOptions,
): middy.MiddlewareObj<
	unknown,
	unknown,
	Error,
	Context<TOptions>,
	Internal<TOptions>
>;

export declare function appConfigValidateOptions(
	options?: Record<string, unknown>,
): void;

export default appConfigMiddleware;