firestoreproto2map

Helper library to convert Firestore Protocol Buffer from event to map that can be used by Firestore

Purpose

This library takes the Protocol Buffer sent from Firestore for a document and converts it to a Java Map Object. Firestore stores the underlying documents as Protocol Buffers and therefore that is what is sent to a Cloud Function when subscribed. If you want to take this and insert it back into Firestore it must be converted to a compatible object, that is what this library does.

Getting Started

This library requires Java 17 and is available in the Maven Central Repository:

<dependency>
    <groupId>com.unitvectory</groupId>
    <artifactId>firestoreproto2map</artifactId>
    <version>0.0.4</version>
</dependency>

Usage

package functions;

import com.google.cloud.functions.CloudEventsFunction;
import com.google.events.cloud.firestore.v1.DocumentEventData;
import com.google.protobuf.InvalidProtocolBufferException;
import com.unitvectory.firestoreproto2map.FirestoreProto2Map;
import io.cloudevents.CloudEvent;
import java.util.logging.Logger;

public class FirebaseFirestore implements CloudEventsFunction {
  private static final Logger logger = Logger.getLogger(FirebaseFirestore.class.getName());

  @Override
  public void accept(CloudEvent event) throws InvalidProtocolBufferException {
    DocumentEventData firestoreEventData = DocumentEventData.parseFrom(event.getData().toBytes());
    
    // This will not handle DocumentReference attributes
    FirestoreProto2Map firestoreProto2Map = new FirestoreProto2Map();

    if (firestoreEventData.hasOldValue()) {
      Map<String, Object> oldValueMap = firestoreProto2Map.convert(firestoreEventData.getOldValue());

      // Map represents object that can be inserted into Firestore
    }

    if (firestoreEventData.hasValue()) {
      Map<String, Object> valueMap = firestoreProto2Map.convert(firestoreEventData.getValue());

      // Map represents object that can be inserted into Firestore
    }
  }
}

Reference Limitation

Firestore supports reference documents, these are handled different from the other field types and require a DocumentReference object which requires the Firestore SDK to get that object.

Firestore firestore  = FirestoreOptions.getDefaultInstance().getService();

// This allows DocumentReference's to be handled
FirestoreProto2Map converter = new FirestoreProto2Map(new ValueToDocumentReferenceMapper() {
    @Override
    public DocumentReference convert(String referenceValue, String documentPath) {
        return firestore.document(documentPath);
    }
});