fix: do not require projectId for samples (#147)

Author: JustinBeckwith

packages/google-cloud-bigquery-datatransfer/README.md

@@ -61,22 +61,12 @@ Google APIs Client Libraries, in [Client Libraries Explained][explained].
 ### Using the client library
 
 ```javascript
-
-if (
-  !process.env.GCLOUD_PROJECT ||
-  !process.env.GOOGLE_APPLICATION_CREDENTIALS
-) {
-  throw new Error(
-    'Usage: GCLOUD_PROJECT=<project_id> GOOGLE_APPLICATION_CREDENTIALS=<path to key json file> node #{$0}'
-  );
-}
-
 const bigqueryDataTransfer = require('@google-cloud/bigquery-data-transfer');
 
 const client = new bigqueryDataTransfer.v1.DataTransferServiceClient({
   // optional auth parameters.
 });
-const projectId = process.env.GCLOUD_PROJECT;
+const projectId = await client.getProjectId();
 
 // Iterate over all elements.
 const formattedParent = client.locationPath(projectId, 'us-central1');

packages/google-cloud-bigquery-datatransfer/samples/quickstart.js

@@ -13,24 +13,12 @@
 // limitations under the License.
 
 'use strict';
-async function main() {
-  // [START bigquerydatatransfer_quickstart]
-
-  if (
-    !process.env.GCLOUD_PROJECT ||
-    !process.env.GOOGLE_APPLICATION_CREDENTIALS
-  ) {
-    throw new Error(
-      'Usage: GCLOUD_PROJECT=<project_id> GOOGLE_APPLICATION_CREDENTIALS=<path to key json file> node #{$0}'
-    );
-  }
 
+// [START bigquerydatatransfer_quickstart]
+async function quickstart() {
   const bigqueryDataTransfer = require('@google-cloud/bigquery-data-transfer');
-
-  const client = new bigqueryDataTransfer.v1.DataTransferServiceClient({
-    // optional auth parameters.
-  });
-  const projectId = process.env.GCLOUD_PROJECT;
+  const client = new bigqueryDataTransfer.v1.DataTransferServiceClient();
+  const projectId = await client.getProjectId();
 
   // Iterate over all elements.
   const formattedParent = client.projectPath(projectId, 'us-central1');
@@ -59,7 +47,6 @@ async function main() {
     .on('data', element => {
       console.log(`  ${element.name}`);
     });
-  // [END bigquerydatatransfer_quickstart]
 }
-
-main().catch(console.error);
+quickstart().catch(console.error);
+// [END bigquerydatatransfer_quickstart]