feat: new sample - Tables: Add empty column (#85)

* feat: new sample - Tables: Add empty column

* format code

* update base on comments

* update base on comments

Author: stephaniewang526

samples/src/main/java/com/example/bigquery/AddEmptyColumn.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_add_empty_column]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.Field;
+import com.google.cloud.bigquery.FieldList;
+import com.google.cloud.bigquery.LegacySQLTypeName;
+import com.google.cloud.bigquery.Schema;
+import com.google.cloud.bigquery.StandardTableDefinition;
+import com.google.cloud.bigquery.Table;
+import java.util.ArrayList;
+import java.util.List;
+
+public class AddEmptyColumn {
+
+  public static void runAddEmptyColumn() {
+    // TODO(developer): Replace these variables before running the sample.
+    String datasetName = "MY_DATASET_NAME";
+    String tableId = "MY_TABLE_NAME";
+    String newColumnName = "NEW_COLUMN_NAME";
+    addEmptyColumn(newColumnName, datasetName, tableId);
+  }
+
+  public static void addEmptyColumn(String newColumnName, String datasetName, String tableId) {
+    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();
+
+      Table table = bigquery.getTable(datasetName, tableId);
+      Schema schema = table.getDefinition().getSchema();
+      FieldList fields = schema.getFields();
+
+      // Create the new field/column
+      Field newField = Field.of(newColumnName, LegacySQLTypeName.STRING);
+
+      // Create a new schema adding the current fields, plus the new one
+      List<Field> fieldList = new ArrayList<Field>();
+      fields.forEach(fieldList::add);
+      fieldList.add(newField);
+      Schema newSchema = Schema.of(fieldList);
+
+      // Update the table with the new schema
+      Table updatedTable =
+          table.toBuilder().setDefinition(StandardTableDefinition.of(newSchema)).build();
+      updatedTable.update();
+      System.out.println("Empty column successfully added to table");
+    } catch (BigQueryException e) {
+      System.out.println("Empty column was not added. \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_add_empty_column]

samples/src/test/java/com/example/bigquery/AddEmptyColumnIT.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.UUID;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class AddEmptyColumnIT {
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+
+  private static final String BIGQUERY_DATASET_NAME = System.getenv("BIGQUERY_DATASET_NAME");
+  private static final String BIGQUERY_TEST_TABLE = System.getenv("BIGQUERY_TEST_TABLE");
+
+  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("BIGQUERY_DATASET_NAME");
+    requireEnvVar("BIGQUERY_TEST_TABLE");
+  }
+
+  @Before
+  public void setUp() throws Exception {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    System.setOut(null);
+  }
+
+  @Test
+  public void addEmptyColumn() {
+    String randomColumnName = "new_" + UUID.randomUUID().toString().replace('-', '_');
+    AddEmptyColumn.addEmptyColumn(randomColumnName, BIGQUERY_DATASET_NAME, BIGQUERY_TEST_TABLE);
+    assertThat(bout.toString()).contains("Empty column successfully added to table");
+  }
+}