Add Spanner stale read sample.

Author: jmdobry

spanner/README.md

@@ -1,8 +1,8 @@
 <img src="https://avatars2.githubusercontent.com/u/2810941?v=3&s=96" alt="Google Cloud Platform logo" title="Google Cloud Platform" align="right" height="96" width="96"/>
 
-# Google Cloud Spanner Node.js Samples
+# Cloud Spanner: Node.js Samples
 
-[![Build](https://storage.googleapis.com/cloud-docs-samples-badges/GoogleCloudPlatform/nodejs-docs-samples/nodejs-docs-samples-spanner.svg)]()
+[![Build](https://storage.googleapis.com/.svg)]()
 
 [Cloud Spanner](https://cloud.google.com/spanner/docs/) is a fully managed, mission-critical, relational database service that offers transactional consistency at global scale, schemas, SQL (ANSI 2011 with extensions), and automatic, synchronous replication for high availability.
 
@@ -18,19 +18,6 @@
 
 ## Setup
 
-1.  Read [Prerequisites][prereq] and [How to run a sample][run] first.
-1.  Install dependencies:
-
-    With **npm**:
-
-        npm install
-
-    With **yarn**:
-
-        yarn install
-
-[prereq]: ../README.md#prerequisites
-[run]: ../README.md#how-to-run-a-sample
 
 ## Samples
 
@@ -70,10 +57,11 @@ __Usage:__ `node crud.js --help`
 
 ```
 Commands:
-  update <instanceName> <databaseName>  Modifies existing rows of data in an example Cloud Spanner table.
-  query <instanceName> <databaseName>   Executes a read-only SQL query against an example Cloud Spanner table.
-  insert <instanceName> <databaseName>  Inserts new rows of data into an example Cloud Spanner table.
-  read <instanceName> <databaseName>    Reads data in an example Cloud Spanner table.
+  update <instanceName> <databaseName>      Modifies existing rows of data in an example Cloud Spanner table.
+  query <instanceName> <databaseName>       Executes a read-only SQL query against an example Cloud Spanner table.
+  insert <instanceName> <databaseName>      Inserts new rows of data into an example Cloud Spanner table.
+  read <instanceName> <databaseName>        Reads data in an example Cloud Spanner table.
+  read-stale <instanceName> <databaseName>  Reads data in an example Cloud Spanner table.
 
 Options:
   --help  Show help                                                                                            [boolean]
@@ -151,14 +139,3 @@ For more information, see https://cloud.google.com/spanner/docs
 
 ## Running the tests
 
-1.  Set the **GCLOUD_PROJECT** and **GOOGLE_APPLICATION_CREDENTIALS** environment variables.
-
-1.  Run the tests:
-
-    With **npm**:
-
-        npm test
-
-    With **yarn**:
-
-        yarn test

spanner/crud.js

@@ -163,6 +163,50 @@ function readData (instanceId, databaseId) {
   // [END read_data]
 }
 
+function readStaleData (instanceId, databaseId) {
+  // [START read_stale_data]
+  // Imports the Google Cloud client library
+  const Spanner = require('@google-cloud/spanner');
+
+  // Instantiates a client
+  const spanner = Spanner();
+
+  // Uncomment these lines to specify the instance and database to use
+  // const instanceId = 'my-instance';
+  // const databaseId = 'my-database';
+
+  // Gets a reference to a Cloud Spanner instance and database
+  const instance = spanner.instance(instanceId);
+  const database = instance.database(databaseId);
+
+  // Read rows from the Albums table
+  const albumsTable = database.table('Albums');
+
+  const query = {
+    columns: ['SingerId', 'AlbumId', 'AlbumTitle'],
+    keySet: {
+      all: true
+    }
+  };
+
+  const options = {
+    // Guarantees that all writes that have committed more than 10 seconds ago
+    // are visible
+    exactStaleness: 10
+  };
+
+  albumsTable.read(query, options)
+    .then((results) => {
+      const rows = results[0];
+
+      rows.forEach((row) => {
+        const json = row.toJSON();
+        console.log(`SingerId: ${json.SingerId.value}, AlbumId: ${json.AlbumId.value}, AlbumTitle: ${json.AlbumTitle}, MarketingBudget: ${json.MarketingBudget}`);
+      });
+    });
+  // [END read_stale_data]
+}
+
 const cli = require(`yargs`)
   .demand(1)
   .command(
@@ -189,6 +233,12 @@ const cli = require(`yargs`)
     {},
     (opts) => readData(opts.instanceName, opts.databaseName)
   )
+  .command(
+    `read-stale <instanceName> <databaseName>`,
+    `Reads data in an example Cloud Spanner table.`,
+    {},
+    (opts) => readStaleData(opts.instanceName, opts.databaseName)
+  )
   .example(`node $0 update "my-instance" "my-database"`)
   .example(`node $0 query "my-instance" "my-database"`)
   .example(`node $0 insert "my-instance" "my-database"`)

spanner/package.json

@@ -22,9 +22,9 @@
   },
   "devDependencies": {
     "@google-cloud/nodejs-repo-tools": "1.4.17",
-    "ava": "0.21.0",
+    "ava": "0.22.0",
     "proxyquire": "1.8.0",
-    "sinon": "3.2.0"
+    "sinon": "3.2.1"
   },
   "cloud-repo-tools": {
     "requiresKeyFile": true,

spanner/system-test/spanner.test.js

@@ -89,6 +89,25 @@ test.serial(`should update existing rows in an example table`, async (t) => {
   t.true(output.includes(`Updated data.`));
 });
 
+// read_stale_data
+test.serial(`should read an example table`, (t) => {
+  t.plan(2);
+  // read-stale-data reads data that is exactly 10 seconds old.  So, make sure
+  // 10 seconds have elapsed since the update_data test.
+  return new Promise((resolve, reject) => {
+    setTimeout(async () => {
+      const output = await tools.runAsync(`${crudCmd} read-stale ${INSTANCE_ID} ${DATABASE_ID}`, cwd);
+      try {
+        t.regex(output, new RegExp(`SingerId: 1, AlbumId: 1, AlbumTitle: Go, Go, Go, MarketingBudget: 100000`));
+        t.regex(output, new RegExp(`SingerId: 2, AlbumId: 2, AlbumTitle: Forever Hold your Peace, MarketingBudget: 500000`));
+        resolve();
+      } catch (err) {
+        reject(err);
+      }
+    }, 11000);
+  });
+});
+
 // query_data_with_new_column
 test.serial(`should query an example table with an additional column and return matching rows`, async (t) => {
   const output = await tools.runAsync(`${schemaCmd} queryNewColumn ${INSTANCE_ID} ${DATABASE_ID}`, cwd);