docs(samples): add relax column load append (#657)

* docs(samples): add relax column load append

* docs(samples): address feedback

Author: Praful Makani

samples/snippets/src/main/java/com/example/bigquery/RelaxColumnLoadAppend.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_relax_column_load_append]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.CsvOptions;
+import com.google.cloud.bigquery.Field;
+import com.google.cloud.bigquery.Job;
+import com.google.cloud.bigquery.JobInfo;
+import com.google.cloud.bigquery.LoadJobConfiguration;
+import com.google.cloud.bigquery.Schema;
+import com.google.cloud.bigquery.StandardSQLTypeName;
+import com.google.cloud.bigquery.Table;
+import com.google.cloud.bigquery.TableId;
+import com.google.common.collect.ImmutableList;
+
+// Sample to append relax column in a table.
+public class RelaxColumnLoadAppend {
+
+  public static void main(String[] args) {
+    // 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";
+    relaxColumnLoadAppend(datasetName, tableName, sourceUri);
+  }
+
+  public static void relaxColumnLoadAppend(String datasetName, String tableName, String sourceUri) {
+    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();
+
+      // Retrieve destination table reference
+      Table table = bigquery.getTable(TableId.of(datasetName, tableName));
+
+      // column as a 'REQUIRED' field.
+      Field name =
+          Field.newBuilder("name", StandardSQLTypeName.STRING).setMode(Field.Mode.REQUIRED).build();
+      Field postAbbr =
+          Field.newBuilder("post_abbr", StandardSQLTypeName.STRING)
+              .setMode(Field.Mode.REQUIRED)
+              .build();
+      Schema schema = Schema.of(name, postAbbr);
+
+      // Skip header row in the file.
+      CsvOptions csvOptions = CsvOptions.newBuilder().setSkipLeadingRows(1).build();
+
+      // Set job options
+      LoadJobConfiguration loadConfig =
+          LoadJobConfiguration.newBuilder(table.getTableId(), sourceUri)
+              .setSchema(schema)
+              .setFormatOptions(csvOptions)
+              .setSchemaUpdateOptions(
+                  ImmutableList.of(JobInfo.SchemaUpdateOption.ALLOW_FIELD_RELAXATION))
+              .setWriteDisposition(JobInfo.WriteDisposition.WRITE_APPEND)
+              .build();
+
+      // Create a load job and wait for it to complete.
+      Job job = bigquery.create(JobInfo.of(loadConfig));
+      job = job.waitFor();
+      // Check the job's status for errors
+      if (job.isDone() && job.getStatus().getError() == null) {
+        System.out.println("Relax column append successfully loaded in a table");
+      } else {
+        System.out.println(
+            "BigQuery was unable to load into the table due to an error:"
+                + job.getStatus().getError());
+      }
+    } catch (BigQueryException | InterruptedException e) {
+      System.out.println("Column not added during load append \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_relax_column_load_append]

samples/snippets/src/test/java/com/example/bigquery/RelaxColumnLoadAppendIT.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.Schema;
+import com.google.cloud.bigquery.StandardSQLTypeName;
+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 RelaxColumnLoadAppendIT {
+
+  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 = "RELAX_COLUMN_LOAD_APPEND_TEST_" + UUID.randomUUID().toString().substring(0, 8);
+    Field id =
+        Field.newBuilder("id", StandardSQLTypeName.INT64).setMode(Field.Mode.REQUIRED).build();
+    Field name =
+        Field.newBuilder("name", StandardSQLTypeName.STRING).setMode(Field.Mode.REQUIRED).build();
+    Field postAbbr =
+        Field.newBuilder("post_abbr", StandardSQLTypeName.STRING)
+            .setMode(Field.Mode.REQUIRED)
+            .build();
+    CreateTable.createTable(BIGQUERY_DATASET_NAME, tableName, Schema.of(id, name, postAbbr));
+
+    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 testRelaxColumnLoadAppend() {
+    String sourceUri = "gs://cloud-samples-data/bigquery/us-states/us-states.csv";
+    RelaxColumnLoadAppend.relaxColumnLoadAppend(BIGQUERY_DATASET_NAME, tableName, sourceUri);
+    assertThat(bout.toString()).contains("Relax column append successfully loaded in a table");
+  }
+}