#402 - Exclude id property using initial value when inserting objects.

We now exclude Id properties from being used in the INSERT field list if the Id value is zero and of a primitive type or if the value is null using a numeric wrapper type.

src/test/java/org/springframework/data/r2dbc/convert/MappingR2dbcConverterUnitTests.java

@@ -20,6 +20,7 @@ import static org.mockito.Mockito.*;
 
 import io.r2dbc.spi.Row;
 import lombok.AllArgsConstructor;
+import lombok.RequiredArgsConstructor;
 
 import java.time.Instant;
 import java.time.LocalDateTime;
@@ -189,6 +190,24 @@ public class MappingR2dbcConverterUnitTests {
 		assertThat(result.entity).isNotNull();
 	}
 
+	@Test // gh-402
+	public void writeShouldSkipPrimitiveIdIfValueIsZero() {
+
+		OutboundRow row = new OutboundRow();
+		converter.write(new WithPrimitiveId(0), row);
+
+		assertThat(row).isEmpty();
+	}
+
+	@Test // gh-402
+	public void writeShouldWritePrimitiveIdIfValueIsNonZero() {
+
+		OutboundRow row = new OutboundRow();
+		converter.write(new WithPrimitiveId(1), row);
+
+		assertThat(row).containsEntry(SqlIdentifier.unquoted("id"), Parameter.fromOrEmpty(1L, Long.TYPE));
+	}
+
 	@AllArgsConstructor
 	static class Person {
 		@Id String id;
@@ -214,6 +233,12 @@ public class MappingR2dbcConverterUnitTests {
 		NonMappableEntity unsupported;
 	}
 
+	@RequiredArgsConstructor
+	static class WithPrimitiveId {
+
+		@Id final long id;
+	}
+
 	static class CustomConversionPerson {
 
 		String foo;