@trpc/server/src/adapters/aws-lambda/index.ts

The tRPC server library

/**
 * If you're making an adapter for tRPC and looking at this file for reference, you should import types and functions from `@trpc/server` and `@trpc/server/http`
 *
 * @example
 * ```ts
 * import type { AnyTRPCRouter } from '@trpc/server'
 * import type { HTTPBaseHandlerOptions } from '@trpc/server/http'
 * ```
 */
import type {
  APIGatewayProxyEventV2,
  Context as APIGWContext,
  StreamifyHandler,
} from 'aws-lambda';
// @trpc/server
import type {
  AnyRouter,
  CreateContextCallback,
  inferRouterContext,
} from '../../@trpc/server';
// @trpc/server
import type {
  HTTPBaseHandlerOptions,
  ResolveHTTPRequestOptionsContextFn,
  TRPCRequestInfo,
} from '../../@trpc/server/http';
import { resolveResponse } from '../../@trpc/server/http';
import type { inferAPIGWReturn, LambdaEvent } from './getPlanner';
import { getPlanner } from './getPlanner';

export type CreateAWSLambdaContextOptions<TEvent extends LambdaEvent> = {
  event: TEvent;
  context: APIGWContext;
  info: TRPCRequestInfo;
};

export type AWSLambdaOptions<
  TRouter extends AnyRouter,
  TEvent extends LambdaEvent,
> = HTTPBaseHandlerOptions<TRouter, TEvent> &
  CreateContextCallback<
    inferRouterContext<AnyRouter>,
    AWSLambdaCreateContextFn<TRouter, TEvent>
  >;

export type AWSLambdaCreateContextFn<
  TRouter extends AnyRouter,
  TEvent extends LambdaEvent,
> = ({
  event,
  context,
  info,
}: CreateAWSLambdaContextOptions<TEvent>) =>
  | inferRouterContext<TRouter>
  | Promise<inferRouterContext<TRouter>>;

export function awsLambdaRequestHandler<
  TRouter extends AnyRouter,
  TEvent extends LambdaEvent,
>(
  opts: AWSLambdaOptions<TRouter, TEvent>,
): (event: TEvent, context: APIGWContext) => Promise<inferAPIGWReturn<TEvent>> {
  return async (event, context) => {
    const planner = getPlanner(event);

    const createContext: ResolveHTTPRequestOptionsContextFn<TRouter> = async (
      innerOpts,
    ) => {
      return await opts.createContext?.({ event, context, ...innerOpts });
    };

    const response = await resolveResponse({
      ...opts,
      createContext,
      req: planner.request,
      path: planner.path,
      error: null,
      onError(o) {
        opts?.onError?.({
          ...o,
          req: event,
        });
      },
    });

    return await planner.toResult(response);
  };
}

export function awsLambdaStreamingRequestHandler<
  TRouter extends AnyRouter,
  TEvent extends APIGatewayProxyEventV2,
>(opts: AWSLambdaOptions<TRouter, TEvent>): StreamifyHandler<TEvent> {
  return async (event, responseStream, context) => {
    const planner = getPlanner(event);

    if (!planner.toStream) {
      throw new Error('Streaming is not supported for this event version');
    }

    const createContext: ResolveHTTPRequestOptionsContextFn<TRouter> = async (
      innerOpts,
    ) => {
      return await opts.createContext?.({ event, context, ...innerOpts });
    };

    const response = await resolveResponse({
      ...opts,
      createContext,
      req: planner.request,
      path: planner.path,
      error: null,
      onError(o) {
        opts?.onError?.({
          ...o,
          req: event,
        });
      },
    });

    await planner.toStream(response, responseStream);
  };
}