Amplify API Wrapper

AmplifyApiClient.ts

import { API, Logger } from 'aws-amplify';

// NOTE: もしAmplify関連で問題を調査したい場合 'DEBUG' にすると細かい挙動が確認できます
Logger.LOG_LEVEL = 'WARN';

export type Headers = object | undefined; // TODO: 適切な型にする
export type QueryParams = object | undefined; // TODO: 適切な型にする
export type Body = object | undefined; // TODO: 適切な型にする
export interface ApiRequest {

  base?: string;

  method: ApiMethod;

  pathResource: string;

  headers?: Headers;

  body?: Body;

  queryStringParameters?: QueryParams;
}

async function mapToApiMethodFunction<T>(
  amplifyAPI: AmplifyAPIClient<T>,
  request: ApiRequest,
): Promise<ApiResponse<T>> {
  switch (request.method) {
    case 'GET': {
      return amplifyAPI.get(request.base, request.pathResource, {
        headers: request.headers,
        body: request.body,
        queryStringParameters: request.queryStringParameters,
      });
    }
    case 'POST': {
      return amplifyAPI.post(request.base, request.pathResource, {
        headers: request.headers,
        body: request.body,
        queryStringParameters: request.queryStringParameters,
      });
    }
    case 'DELETE': {
      return amplifyAPI.del(request.base, request.pathResource, {
        headers: request.headers,
        body: request.body,
        queryStringParameters: request.queryStringParameters,
      });
    }
    case 'PUT': {
      return amplifyAPI.put(request.base, request.pathResource, {
        headers: request.headers,
        body: request.body,
        queryStringParameters: request.queryStringParameters,
      });
    }
    case 'PATCH': {
      return amplifyAPI.patch(request.base, request.pathResource, {
        headers: request.headers,
        body: request.body,
        queryStringParameters: request.queryStringParameters,
      });
    }
    default: {
      return Promise.reject(new Error('never call case'));
    }
  }
}

export async function send<T>(request: ApiRequest): Promise<T> {
  return mapToApiMethodFunction<T>(API, request).then((response) => {
    return response;
  });
}

export type ApiMethod = 'GET' | 'POST' | 'DELETE' | 'PATCH' | 'PUT';

type ApiMethodFunctionParameters = undefined | {
  headers: undefined | object;
  body: undefined | object;
  queryStringParameters: undefined | object;
  withCredentials?: boolean;
};

type ApiResponse<T> = T;

interface AmplifyAPIClient<T> {
  get(apiName: string,
      path: string,
      parameters: ApiMethodFunctionParameters): Promise<ApiResponse<T>>;
  post(apiName: string,
       path: string,
       parameters: ApiMethodFunctionParameters): Promise<ApiResponse<T>>;
  del(apiName: string,
      path: string,
      parameters: ApiMethodFunctionParameters): Promise<ApiResponse<T>>;
  patch(apiName: string,
        path: string,
        parameters: ApiMethodFunctionParameters): Promise<ApiResponse<T>>;
  put(apiName: string,
      path: string,
      parameters: ApiMethodFunctionParameters): Promise<ApiResponse<T>>;
}

example.ts

import * as api from '../api/AmplifyApiClient';

export type ExampleResponse = {
  name: string
}
export async function getExample(id: number): Promise<ExampleResponse> {
  return api.send({
    method: 'GET',
    pathResource: `/example/${id}`,
    headers: {},
    // NOTE: GETでbodyに空オブジェクトを入れるとSigned Requestで必ず失敗する
    // @see https://github.com/aws-amplify/amplify-js/issues/3534
    body: null,
  });
}