feat: Support getOrNull and getOrDefault in Struct

Author: sakthivelmanii

google-cloud-spanner/src/main/java/com/google/cloud/spanner/StructReader.java

@@ -176,6 +176,38 @@ default float getFloat(String columnName) {
    */
   String getString(String columnName);
 
+  /**
+   * @param columnIndex index of the column
+   * @return the value of a column with type T. return value(T) can be null.
+   */
+  default <T> T getOrNull(int columnIndex, Function<Integer, T> function) {
+    return isNull(columnIndex) ? null : function.apply(columnIndex);
+  }
+
+  /**
+   * @param columnName index of the column
+   * @return the value of a column with type T. return value(T) can be null.
+   */
+  default <T> T getOrNull(String columnName, Function<String, T> function) {
+    return isNull(columnName) ? null : function.apply(columnName);
+  }
+
+  /**
+   * @param columnIndex index of the column
+   * @return the value of a column with type T. if column value is null, returns default value.
+   */
+  default <T> T getOrDefault(int columnIndex, Function<Integer, T> function, T defaultValue) {
+    return isNull(columnIndex) ? defaultValue : function.apply(columnIndex);
+  }
+
+  /**
+   * @param columnName name of the column
+   * @return the value of a column with type T. if column value is null, returns default value.
+   */
+  default <T> T getOrDefault(String columnName, Function<String, T> function, T defaultValue) {
+    return isNull(columnName) ? defaultValue : function.apply(columnName);
+  }
+
   /**
    * @param columnIndex index of the column
    * @return the value of a non-{@code NULL} column with type {@link Type#json()}.

google-cloud-spanner/src/test/java/com/google/cloud/spanner/StructTest.java

@@ -57,6 +57,48 @@ public void builder() {
     assertThat(struct.getLong(1)).isEqualTo(2);
   }
 
+  @Test
+  public void getOrNullTests() {
+    Struct struct =
+        Struct.newBuilder()
+            .set("f1")
+            .to("x")
+            .set("f2")
+            .to(2)
+            .set("f3")
+            .to(Value.bool(null))
+            .build();
+    String column1 = struct.getOrNull(0, struct::getString);
+    assertThat(column1).isEqualTo("x");
+
+    Long column2 = struct.getOrNull(1, struct::getLong);
+    assertThat(column2).isEqualTo(2);
+
+    String column3 = struct.getOrNull("f3", struct::getString);
+    assertThat(column3).isNull();
+  }
+
+  @Test
+  public void getOrDefaultTests() {
+    Struct struct =
+        Struct.newBuilder()
+            .set("f1")
+            .to("x")
+            .set("f2")
+            .to(2)
+            .set("f3")
+            .to(Value.bool(null))
+            .build();
+    String column1 = struct.getOrDefault(0, struct::getString, "");
+    assertThat(column1).isEqualTo("x");
+
+    Long column2 = struct.getOrDefault("f2", struct::getLong, -1L);
+    assertThat(column2).isEqualTo(2);
+
+    String column3 = struct.getOrDefault(2, struct::getString, "");
+    assertThat(column3).isEqualTo("");
+  }
+
   @Test
   public void duplicateFields() {
     // Duplicate fields are allowed - some SQL queries produce this type of value.