@aws-amplify/core/dist/cjs/clients/internal/composeServiceApi.js

Core category of aws-amplify

'use strict';

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
Object.defineProperty(exports, "__esModule", { value: true });
exports.composeServiceApi = void 0;
/**
 * Compose a service API handler that accepts input as defined shape and responds conforming to defined output shape.
 * A service API handler is composed with:
 * * A transfer handler
 * * A serializer function
 * * A deserializer function
 * * A default config object
 *
 * The returned service API handler, when called, will trigger the following workflow:
 * 1. When calling the service API handler function, the default config object is merged into the input config
 * object to assign the default values of some omitted configs, resulting to a resolved config object.
 * 2. The `endpointResolver` function from the default config object will be invoked with the resolved config object and
 * API input object resulting to an endpoint instance.
 * 3. The serializer function is invoked with API input object and the endpoint instance resulting to an HTTP request
 * instance.
 * 4. The HTTP request instance and the resolved config object is passed to the transfer handler function.
 * 5. The transfer handler function resolves to an HTTP response instance(can be either successful or failed status code).
 * 6. The deserializer function is invoked with the HTTP response instance resulting to the API output object, and
 * return to the caller.
 *
 *
 * @param transferHandler Async function for dispatching HTTP requests and returning HTTP response.
 * @param serializer  Async function for converting object in defined input shape into HTTP request targeting a given
 * 	endpoint.
 * @param deserializer Async function for converting HTTP response into output object in defined output shape, or error
 * 	shape.
 * @param defaultConfig  object containing default options to be consumed by transfer handler, serializer and
 *  deserializer.
 * @returns a async service API handler function that accepts a config object and input object in defined shape, returns
 * 	an output object in defined shape. It may also throw error instance in defined shape in deserializer. The config
 *  object type is composed with options type of transferHandler, endpointResolver function as well as endpointResolver
 *  function's input options type, region string. The config object property will be marked as optional if it's also
 * 	defined in defaultConfig.
 *
 * @internal
 */
const composeServiceApi = (transferHandler, serializer, deserializer, defaultConfig) => {
    return async (config, input) => {
        const resolvedConfig = {
            ...defaultConfig,
            ...config,
        };
        // We need to allow different endpoints based on both given config(other than region) and input.
        // However for most of non-S3 services, region is the only input for endpoint resolver.
        const endpoint = await resolvedConfig.endpointResolver(resolvedConfig, input);
        // Unlike AWS SDK clients, a serializer should NOT populate the `host` or `content-length` headers.
        // Both of these headers are prohibited per Spec(https://developer.mozilla.org/en-US/docs/Glossary/Forbidden_header_name).
        // They will be populated automatically by browser, or node-fetch polyfill.
        const request = await serializer(input, endpoint);
        const response = await transferHandler(request, {
            ...resolvedConfig,
        });
        return deserializer(response);
    };
};
exports.composeServiceApi = composeServiceApi;
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