Last active
June 9, 2022 17:01
-
-
Save egalpin/c1ca7c58ee5e6fb1b67c5afd477fb339 to your computer and use it in GitHub Desktop.
Jackson JSON serializer for Google Datastore Entity
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import com.fasterxml.jackson.core.JsonGenerator; | |
| import com.fasterxml.jackson.databind.SerializerProvider; | |
| import com.fasterxml.jackson.databind.ser.std.StdSerializer; | |
| import com.google.cloud.Timestamp; | |
| import com.google.cloud.datastore.Blob; | |
| import com.google.cloud.datastore.Entity; | |
| import com.google.cloud.datastore.Key; | |
| import com.google.cloud.datastore.Value; | |
| import java.io.IOException; | |
| import java.io.UnsupportedEncodingException; | |
| import java.util.Base64; | |
| import java.util.List; | |
| import java.util.Map; | |
| import java.util.concurrent.TimeUnit; | |
| import org.slf4j.Logger; | |
| import org.slf4j.LoggerFactory; | |
| public class DatastoreEntitySerializer extends StdSerializer<Entity> { | |
| private static final Logger LOG = LoggerFactory.getLogger(DatastoreEntitySerializer.class); | |
| public DatastoreEntitySerializer() { | |
| this(null); | |
| } | |
| public DatastoreEntitySerializer(Class<Entity> t) { | |
| super(t); | |
| } | |
| private static void _serialize(Value<?> value, JsonGenerator gen) throws IOException { | |
| switch (value.getType()) { | |
| case STRING: | |
| if ("null".equals(value.get())) { | |
| gen.writeNull(); | |
| break; | |
| } | |
| gen.writeString((String) value.get()); | |
| break; | |
| case KEY: | |
| Key k = (Key) value.get(); | |
| gen.writeObject(k); | |
| break; | |
| case BLOB: | |
| String encodedString = | |
| Base64.getEncoder().encodeToString(((Blob) value.get()).toByteArray()); | |
| gen.writeString(encodedString); | |
| break; | |
| case BOOLEAN: | |
| gen.writeBoolean((boolean) value.get()); | |
| break; | |
| case DOUBLE: | |
| gen.writeNumber((double) value.get()); | |
| break; | |
| case NULL: | |
| gen.writeNull(); | |
| break; | |
| case LONG: | |
| gen.writeNumber((long) value.get()); | |
| break; | |
| case TIMESTAMP: | |
| gen.writeNumber(toMillis((Timestamp) value.get())); | |
| break; | |
| case LIST: | |
| gen.writeStartArray(); | |
| for (Value<?> v : (List<Value<?>>) value.get()) { | |
| _serialize(v, gen); | |
| } | |
| gen.writeEndArray(); | |
| break; | |
| case ENTITY: | |
| serializeEntity((Entity) value.get(), gen); | |
| break; | |
| case LAT_LNG: | |
| gen.writeString(value.get().toString()); | |
| break; | |
| case RAW_VALUE: | |
| default: | |
| throw new UnsupportedEncodingException( | |
| String.format("Cannot encode Datastore type %s", value.getType())); | |
| } | |
| } | |
| public static void serializeEntity(Entity entity, JsonGenerator gen) throws IOException { | |
| gen.writeStartObject(); | |
| Map<String, Value<?>> valueMap = entity.getProperties(); | |
| for (String field : entity.getNames()) { | |
| Value<?> value = valueMap.get(field); | |
| // value can only be one of ValueType enum | |
| gen.writeFieldName(field); | |
| try { | |
| _serialize(value, gen); | |
| } catch (UnsupportedEncodingException e) { | |
| LOG.error( | |
| String.format( | |
| "Failed to serialize field %s from entity with Key %s", field, entity.getKey())); | |
| throw e; | |
| } | |
| } | |
| gen.writeEndObject(); | |
| } | |
| private static long toMillis(Timestamp t) { | |
| long secondsInMilliseconds = TimeUnit.SECONDS.toMillis(t.getSeconds()); | |
| long nanosInMilliseconds = TimeUnit.NANOSECONDS.toMillis(t.getNanos()); | |
| return secondsInMilliseconds + nanosInMilliseconds; | |
| } | |
| @Override | |
| public void serialize(Entity entity, JsonGenerator gen, SerializerProvider provider) | |
| throws IOException { | |
| serializeEntity(entity, gen); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment