docs(samples): add export model (#970)

samples/snippets/src/main/java/com/example/bigquery/ExtractModel.java

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+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.bigquery;
+
+// [START bigquery_export_model]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.ExtractJobConfiguration;
+import com.google.cloud.bigquery.Job;
+import com.google.cloud.bigquery.JobInfo;
+import com.google.cloud.bigquery.ModelId;
+
+// Sample to extract model to GCS bucket
+public class ExtractModel {
+
+  public static void main(String[] args) throws InterruptedException {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectName = "bigquery-public-data";
+    String datasetName = "samples";
+    String modelName = "model";
+    String bucketName = "MY-BUCKET-NAME";
+    String destinationUri = "gs://" + bucketName + "/path/to/file";
+    extractModel(projectName, datasetName, modelName, destinationUri);
+  }
+
+  public static void extractModel(
+      String projectName, String datasetName, String modelName, String destinationUri)
+      throws InterruptedException {
+    try {
+      // Initialize client that will be used to send requests. This client only needs to be created
+      // once, and can be reused for multiple requests.
+      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();
+
+      ModelId modelId = ModelId.of(projectName, datasetName, modelName);
+
+      ExtractJobConfiguration extractConfig =
+          ExtractJobConfiguration.newBuilder(modelId, destinationUri).build();
+
+      Job job = bigquery.create(JobInfo.of(extractConfig));
+
+      // Blocks until this job completes its execution, either failing or succeeding.
+      Job completedJob = job.waitFor();
+      if (completedJob == null) {
+        System.out.println("Job not executed since it no longer exists.");
+        return;
+      } else if (completedJob.getStatus().getError() != null) {
+        System.out.println(
+            "BigQuery was unable to extract due to an error: \n" + job.getStatus().getError());
+        return;
+      }
+      System.out.println("Model extract successful");
+    } catch (BigQueryException ex) {
+      System.out.println("Model extraction job was interrupted. \n" + ex.toString());
+    }
+  }
+}
+// [END bigquery_export_model]

samples/snippets/src/test/java/com/example/bigquery/ExtractModelIT.java

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+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.bigquery;
+
+import static com.google.common.truth.Truth.assertThat;
+import static junit.framework.TestCase.assertNotNull;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class ExtractModelIT {
+
+  private final Logger log = Logger.getLogger(this.getClass().getName());
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+  private PrintStream originalPrintStream;
+
+  private static final String GCS_BUCKET = System.getenv("GCS_BUCKET");
+
+  private static void requireEnvVar(String varName) {
+    assertNotNull(
+        "Environment variable " + varName + " is required to perform these tests.",
+        System.getenv(varName));
+  }
+
+  @BeforeClass
+  public static void checkRequirements() {
+    requireEnvVar("GCS_BUCKET");
+  }
+
+  @Before
+  public void setUp() {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    originalPrintStream = System.out;
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    // restores print statements in the original method
+    System.out.flush();
+    System.setOut(originalPrintStream);
+    log.log(Level.INFO, bout.toString());
+  }
+
+  @Test
+  public void testExtractModel() throws InterruptedException {
+    String projectId = "bigquery-public-data";
+    String datasetName = "samples";
+    String modelName = "model";
+    String destinationUri = "gs://" + GCS_BUCKET + "/extractModel";
+    // Extract model content to GCS
+    ExtractModel.extractModel(projectId, datasetName, modelName, destinationUri);
+    assertThat(bout.toString()).contains("Model extract successful");
+  }
+}