docs(samples): add load CSV from GCS to overwrite table sample (#428)

Author: stephaniewang526

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

@@ -0,0 +1,82 @@
+/*
+ * 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_load_table_gcs_csv_truncate]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.FormatOptions;
+import com.google.cloud.bigquery.Job;
+import com.google.cloud.bigquery.JobInfo;
+import com.google.cloud.bigquery.JobInfo.WriteDisposition;
+import com.google.cloud.bigquery.LoadJobConfiguration;
+import com.google.cloud.bigquery.TableId;
+
+// Sample to overwrite the BigQuery table data by loading a CSV file from GCS
+public class LoadCsvFromGcsTruncate {
+
+  public static void runLoadCsvFromGcsTruncate() throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String datasetName = "MY_DATASET_NAME";
+    String tableName = "MY_TABLE_NAME";
+    String sourceUri = "gs://cloud-samples-data/bigquery/us-states/us-states.csv";
+    loadCsvFromGcsTruncate(datasetName, tableName, sourceUri);
+  }
+
+  public static void loadCsvFromGcsTruncate(String datasetName, String tableName, String sourceUri)
+      throws Exception {
+    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();
+
+      TableId tableId = TableId.of(datasetName, tableName);
+
+      LoadJobConfiguration configuration =
+          LoadJobConfiguration.builder(tableId, sourceUri)
+              .setFormatOptions(FormatOptions.csv())
+              // Set the write disposition to overwrite existing table data
+              .setWriteDisposition(WriteDisposition.WRITE_TRUNCATE)
+              .build();
+
+      // For more information on Job see:
+      // https://googleapis.dev/java/google-cloud-clients/latest/index.html?com/google/cloud/bigquery/package-summary.html
+      // Load the table
+      Job loadJob = bigquery.create(JobInfo.of(configuration));
+
+      // Load data from a GCS parquet file into the table
+      // Blocks until this load table job completes its execution, either failing or succeeding.
+      Job completedJob = loadJob.waitFor();
+
+      // Check for errors
+      if (completedJob == null) {
+        throw new Exception("Job not executed since it no longer exists.");
+      } else if (completedJob.getStatus().getError() != null) {
+        // You can also look at queryJob.getStatus().getExecutionErrors() for all
+        // errors, not just the latest one.
+        throw new Exception(
+            "BigQuery was unable to load into the table due to an error: \n"
+                + loadJob.getStatus().getError());
+      }
+      System.out.println("Table is successfully overwritten by CSV file loaded from GCS");
+    } catch (BigQueryException | InterruptedException e) {
+      System.out.println("Column not added during load append \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_load_table_gcs_csv_truncate]

samples/snippets/src/test/java/com/example/bigquery/LoadCsvFromGcsTruncateTest.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 com.google.cloud.bigquery.Field;
+import com.google.cloud.bigquery.LegacySQLTypeName;
+import com.google.cloud.bigquery.Schema;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.UUID;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class LoadCsvFromGcsTruncateTest {
+
+  private String tableName;
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+
+  private static final String BIGQUERY_DATASET_NAME = requireEnvVar("BIGQUERY_DATASET_NAME");
+
+  private static String requireEnvVar(String varName) {
+    String value = System.getenv(varName);
+    assertNotNull(
+        "Environment variable " + varName + " is required to perform these tests.",
+        System.getenv(varName));
+    return value;
+  }
+
+  @BeforeClass
+  public static void checkRequirements() {
+    requireEnvVar("BIGQUERY_DATASET_NAME");
+  }
+
+  @Before
+  public void setUp() {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+
+    // Create a test table
+    tableName = "loadCsvFromGcsTruncate_TEST_" + UUID.randomUUID().toString().replace('-', '_');
+
+    Schema schema =
+        Schema.of(
+            Field.of("name", LegacySQLTypeName.STRING),
+            Field.of("post_abbr", LegacySQLTypeName.STRING));
+
+    CreateTable.createTable(BIGQUERY_DATASET_NAME, tableName, schema);
+
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    // Clean up
+    DeleteTable.deleteTable(BIGQUERY_DATASET_NAME, tableName);
+    System.setOut(null);
+  }
+
+  @Test
+  public void loadCsvFromGcsTruncate() throws Exception {
+    String sourceUri = "gs://cloud-samples-data/bigquery/us-states/us-states.csv";
+    LoadCsvFromGcsTruncate.loadCsvFromGcsTruncate(BIGQUERY_DATASET_NAME, tableName, sourceUri);
+    assertThat(bout.toString())
+        .contains("Table is successfully overwritten by CSV file loaded from GCS");
+  }
+}