Comparison Shopping Service API Samples

This repository contains code samples for the Comparison Shopping Service API (CSS API). The code samples are categorized by platform/language. Each language directory contains a README file with more information on how to run the samples for that particular language.

This document covers setting up authentication and the common configuration file used by all the samples. For more information on the API, please refer to the CSS API documentation.

Choose Your Method of Authentication

Before getting started, check the Getting Started section of the CSS API documentation. You may want to use service accounts to simplify the authentication flow. These samples also support using Google Application Default Credentials.

Note The current CSS API sample code only demonstrates the use of service accounts for authentication. Other OAuth authentication methods are also supported, but these are not explicitly demonstrated in the API samples.

Setting up Authentication and Sample Configuration

1. Create the directory $(HOME)/comparison-shopping-service-api/config to store the configuration.

   If you are unsure of the location of this directory in your particular setup, you may run the samples (following the language-specific README). Errors from the samples that relate to this directory or necessary files not existing will provide the full path to the expected directory or files.

2. Set up your desired authentication method.

   If you are using Google Application Default Credentials:

   • Follow the directions on the Google Application Default Credentials page.

   If you are using a service account:

   • Rename the JSON file downloaded during service account creation to service-account.json in the config directory.

   If you are using an OAuth 2.0 client ID:

   • Download your OAuth 2.0 client credentials to the file client-secrets.json in the config directory.

     Note: The samples assume that you are using an OAuth 2.0 client ID that can use a loopback IP address to retrieve tokens. If you are not or are unsure that you are, please visit the OAuth 2.0 for Mobile & Desktop Apps page and follow the instructions there to create a new OAuth 2.0 client ID to use with the samples.

   It is possible to set up multiple authentication methods for testing different flows, but it is important to note that the samples will always use the first credentials that can be loaded, in the following order:

   1. Google Application Default Credentials
   2. Service accounts credentials
   3. OAuth 2.0 client credentials

3. Copy the example account-info.json file from the repository root to $HOME/comparison-shopping-service-api/config. Then, modify its contents as needed. The file contains a JSON object with the following fields:

   Field	Type	Description
   groupId	number	The CSS Group ID to run samples against.
   domainId	number	The CSS Domain ID to run samples against.
   merchantId	number	The Merchant Center ID to run samples against.

   If OAuth 2.0 client credentials are used, the token details will be stored in the stored-token.json file in the samples configuration directory after authorization has been granted. If authentication issues are encountered, the file can be removed and the user will be prompted to re-authorize access.

Try Out the Samples

Once the common sample configuration file has been configured and authentication credentials have been set up, it is time to build and run any of the included samples. As previously mentioned, language-specific instructions are available in the READMEs located in each language subdirectory.