feat: GoogleCloudPlatform#2576 Added typeadapter to read and write Instant values.

Author: ablx

spring-cloud-gcp-data-spanner/src/main/java/com/google/cloud/spring/data/spanner/core/mapping/SpannerMappingContext.java

@@ -18,7 +18,9 @@
 
 import com.google.cloud.spring.data.spanner.core.convert.ConverterAwareMappingSpannerEntityProcessor;
 import com.google.cloud.spring.data.spanner.core.convert.SpannerEntityProcessor;
+import com.google.cloud.spring.data.spanner.core.mapping.typeadapter.InstantTypeAdapter;
 import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
 import org.springframework.beans.BeansException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
@@ -31,6 +33,8 @@
 import org.springframework.lang.NonNull;
 import org.springframework.util.Assert;
 
+import java.time.Instant;
+
 /**
  * A mapping context for Cloud Spanner that provides ways to create persistent entities and
  * properties.
@@ -55,7 +59,7 @@ public SpannerMappingContext() {
 
   public SpannerMappingContext(Gson gson) {
     Assert.notNull(gson, "A non-null gson is required.");
-    this.gson = gson;
+    this.gson = addTypeAdapter(gson, new InstantTypeAdapter(), Instant.class);
   }
 
   @NonNull
@@ -124,4 +128,9 @@ public SpannerPersistentEntity<?> getPersistentEntityOrFail(Class<?> entityClass
     }
     return entity;
   }
+
+  private <T> Gson addTypeAdapter(Gson gson, TypeAdapter<T> typeAdapter, Class<T> type) {
+
+    return     gson.newBuilder().registerTypeAdapter(type, typeAdapter).create();
+  }
 }

spring-cloud-gcp-data-spanner/src/main/java/com/google/cloud/spring/data/spanner/core/mapping/typeadapter/InstantTypeAdapter.java

@@ -0,0 +1,29 @@
+package com.google.cloud.spring.data.spanner.core.mapping.typeadapter;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+
+import java.io.IOException;
+import java.time.Instant;
+
+public class InstantTypeAdapter extends TypeAdapter<Instant> {
+    @Override
+    public void write(JsonWriter jsonWriter, Instant instant) throws IOException {
+        if (instant == null) {
+            jsonWriter.nullValue();
+        } else {
+            jsonWriter.value(instant.toString());
+        }
+    }
+
+    @Override
+    public Instant read(JsonReader jsonReader) throws IOException {
+        System.out.println(jsonReader.peek());
+        if (jsonReader.peek() == JsonToken.NULL) {
+            return null;
+        }
+        return Instant.parse(jsonReader.nextString());
+    }
+}

spring-cloud-gcp-data-spanner/src/test/java/com/google/cloud/spring/data/spanner/core/convert/ConverterAwareMappingSpannerEntityReaderTests.java

@@ -19,6 +19,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatNoException;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.InstanceOfAssertFactories.INSTANT;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -41,6 +42,8 @@
 import com.google.cloud.spring.data.spanner.core.mapping.SpannerDataException;
 import com.google.cloud.spring.data.spanner.core.mapping.SpannerMappingContext;
 import com.google.gson.Gson;
+
+import java.time.Instant;
 import java.util.Arrays;
 import java.util.List;
 import org.junit.jupiter.api.BeforeEach;
@@ -397,6 +400,30 @@ void readJsonFieldTest() {
     assertThat(result.params.p2).isEqualTo("5");
   }
 
+  @Test
+  void readJsonInstantFieldTest() {
+    Struct row = mock(Struct.class);
+    when(row.getString("id")).thenReturn("1234");
+    when(row.getType())
+            .thenReturn(
+                    Type.struct(
+                            Arrays.asList(
+                                    Type.StructField.of("id", Type.string()),
+                                    Type.StructField.of("params", Type.json()))));
+    when(row.getColumnType("id")).thenReturn(Type.string());
+
+    when(row.getJson("params")).thenReturn("{\"instant\":\"1970-01-01T00:00:00Z\"}");
+
+    TestEntities.TestEntityInstantInJson result =
+            this.spannerEntityReader.read(TestEntities.TestEntityInstantInJson.class, row);
+
+    assertThat(result.id).isEqualTo("1234");
+
+    assertThat(result.params.instant).isEqualTo(Instant.ofEpochSecond(0));
+  }
+
+
+
   @Test
   void readArrayJsonFieldTest() {
     Struct row = mock(Struct.class);

spring-cloud-gcp-data-spanner/src/test/java/com/google/cloud/spring/data/spanner/core/convert/ConverterAwareMappingSpannerEntityWriterTests.java

@@ -366,6 +366,22 @@ void writeJsonTest() {
     verify(valueBinder).to(testEntity.id);
     verify(valueBinder).to(Value.json("{\"p1\":\"some value\",\"p2\":\"some other value\"}"));
   }
+  @Test
+  void writeJsonWithInstantTest() {
+    TestEntities.InstantParam parameters = new TestEntities.InstantParam(Instant.ofEpochSecond(0));
+    TestEntities.TestEntityInstantInJson testEntity = new TestEntities.TestEntityInstantInJson("id1", parameters);
+
+    WriteBuilder writeBuilder = mock(WriteBuilder.class);
+    ValueBinder<WriteBuilder> valueBinder = mock(ValueBinder.class);
+
+    when(writeBuilder.set("id")).thenReturn(valueBinder);
+    when(writeBuilder.set("params")).thenReturn(valueBinder);
+
+    this.spannerEntityWriter.write(testEntity, writeBuilder::set);
+
+    verify(valueBinder).to(testEntity.id);
+    verify(valueBinder).to(Value.json("{\"instant\":\"1970-01-01T00:00:00Z\"}"));
+  }
 
   @Test
   void writeNullJsonTest() {