making it non-static

firebase-firestore/src/main/java/com/google/firebase/firestore/CollectionReference.java

@@ -125,8 +125,7 @@ public DocumentReference document(@NonNull String documentPath) {
   public Task<DocumentReference> add(@NonNull Object data) {
     checkNotNull(data, "Provided data must not be null.");
     final DocumentReference ref = document();
-    // TODO: Assert fields annotated with DocumentId in `data` are set to null.
-    return ref.setForAddition(data)
+    return ref.set(data)
         .continueWith(
             Executors.DIRECT_EXECUTOR,
             task -> {

firebase-firestore/src/main/java/com/google/firebase/firestore/DocumentId.java

@@ -21,21 +21,14 @@
 import java.lang.annotation.Target;
 
 /**
- * Annotation used to mark an object field to be the ID of a firestore document.
- *
- * <p>This annotation is recognized by {@link com.google.firebase.firestore.util.CustomClassMapper}.
- *
- * <p>During conversions from documents to java objects, fields with this annotation will be
- * populated with the document ID being converted.
- *
- * <p>When objects with the annotation is used to create new documents, its field value must be null
- * to guarantee uniqueness, otherwise a runtime exception will be thrown.
- *
- * <p>When objects with the annotation is used to update documents, its field value must match the
- * target documents, otherwise a runtime exception will be thrown.
+ * Annotation used to mark a POJO field to be automatically populated with the document's ID when
+ * the POJO is created from a Firestore document (e.g. via {@link DocumentSnapshot#toObject}).
  *
  * <p>This annotation can only be applied to fields of String or {@link DocumentReference},
  * otherwise a runtime exception will be thrown.
+ *
+ * <p>When writing a POJO to Firestore, the @DocumentId-annotated field must either be null or match
+ * the document ID of the document being written to, else a runtime exception will be thrown.
  */
 @PublicApi
 @Retention(RetentionPolicy.RUNTIME)

firebase-firestore/src/main/java/com/google/firebase/firestore/DocumentReference.java

@@ -154,13 +154,6 @@ public Task<Void> set(@NonNull Object data) {
     return set(data, SetOptions.OVERWRITE);
   }
 
-  // Handles specific logic for document addition before entering comment `set` logic.
-  /* package */ Task<Void> setForAddition(@NonNull Object data) {
-    checkNotNull(data, "Provided data must not be null.");
-    // TODO: Assert fields annotated with DocumentId in `data` are set to null.
-    return setImpl(data, SetOptions.OVERWRITE);
-  }
-
   /**
    * Writes to the document referred to by this DocumentReference. If the document does not yet
    * exist, it will be created. If you pass {@link SetOptions}, the provided data can be merged into
@@ -176,16 +169,10 @@ public Task<Void> set(@NonNull Object data) {
   public Task<Void> set(@NonNull Object data, @NonNull SetOptions options) {
     checkNotNull(data, "Provided data must not be null.");
     checkNotNull(options, "Provided options must not be null.");
-    // TODO: Assert fields annotated with DocumentId in `data` match `documentRef`.
-    return setImpl(data, options);
-  }
-
-  @NonNull
-  private Task<Void> setImpl(@NonNull Object data, @NonNull SetOptions options) {
     ParsedSetData parsed =
         options.isMerge()
-            ? firestore.getDataConverter().parseMergeData(data, options.getFieldMask())
-            : firestore.getDataConverter().parseSetData(data);
+            ? firestore.getDataConverter().parseMergeData(data, options.getFieldMask(), getId())
+            : firestore.getDataConverter().parseSetData(data, getId());
     return firestore
         .getClient()
         .write(parsed.toMutationList(key, Precondition.NONE))

firebase-firestore/src/main/java/com/google/firebase/firestore/DocumentSnapshot.java

@@ -200,7 +200,10 @@ public <T> T toObject(
     checkNotNull(
         serverTimestampBehavior, "Provided serverTimestampBehavior value must not be null.");
     Map<String, Object> data = getData(serverTimestampBehavior);
-    return data == null ? null : CustomClassMapper.convertToCustomClass(data, valueType);
+    return data == null
+        ? null
+        : CustomClassMapper.withDocumentId(key.getPath().getLastSegment())
+            .convertToCustomClass(data, valueType);
   }
 
   /**
@@ -353,7 +356,10 @@ public <T> T get(
       @NonNull Class<T> valueType,
       @NonNull ServerTimestampBehavior serverTimestampBehavior) {
     Object data = get(fieldPath, serverTimestampBehavior);
-    return data == null ? null : CustomClassMapper.convertToCustomClass(data, valueType);
+    return data == null
+        ? null
+        : CustomClassMapper.withDocumentId(key.getPath().getLastSegment())
+            .convertToCustomClass(data, valueType);
   }
 
   /**

firebase-firestore/src/main/java/com/google/firebase/firestore/Transaction.java

@@ -88,11 +88,12 @@ public Transaction set(
     firestore.validateReference(documentRef);
     checkNotNull(data, "Provided data must not be null.");
     checkNotNull(options, "Provided options must not be null.");
-    // TODO: Assert fields annotated with DocumentId in `data` match `documentRef`.
     ParsedSetData parsed =
         options.isMerge()
-            ? firestore.getDataConverter().parseMergeData(data, options.getFieldMask())
-            : firestore.getDataConverter().parseSetData(data);
+            ? firestore
+                .getDataConverter()
+                .parseMergeData(data, options.getFieldMask(), documentRef.getId())
+            : firestore.getDataConverter().parseSetData(data, documentRef.getId());
     transaction.set(documentRef.getKey(), parsed);
     return this;
   }

firebase-firestore/src/main/java/com/google/firebase/firestore/UserDataConverter.java

@@ -73,17 +73,33 @@ public UserDataConverter(DatabaseId databaseId) {
     this.databaseId = databaseId;
   }
 
-  /** Parse document data from a non-merge set() call. */
-  public ParsedSetData parseSetData(Object input) {
+  /**
+   * Parse document data from a non-merge set() call.
+   *
+   * @param input A POJO object representing document data.
+   * @param expectedId If `input` has any fields annotated with {@link DocumentId}, they should
+   *     either be null or match this parameter.
+   */
+  public ParsedSetData parseSetData(Object input, String expectedId) {
     ParseAccumulator accumulator = new ParseAccumulator(UserData.Source.Set);
-    ObjectValue updateData = convertAndParseDocumentData(input, accumulator.rootContext());
+    ObjectValue updateData =
+        convertAndParseDocumentData(input, accumulator.rootContext(), expectedId);
     return accumulator.toSetData(updateData);
   }
 
-  /** Parse document data from a set() call with SetOptions.merge() set. */
-  public ParsedSetData parseMergeData(Object input, @Nullable FieldMask fieldMask) {
+  /**
+   * Parse document data from a set() call with SetOptions.merge() set.
+   *
+   * @param input A POJO object representing document data.
+   * @param fieldMask A {@link FieldMask} object representing the fields to be merged.
+   * @param expectedId If `input` has any fields annotated with {@link DocumentId}, they should
+   *     either be null or match this parameter.
+   */
+  public ParsedSetData parseMergeData(
+      Object input, @Nullable FieldMask fieldMask, String expectedId) {
     ParseAccumulator accumulator = new ParseAccumulator(UserData.Source.MergeSet);
-    ObjectValue updateData = convertAndParseDocumentData(input, accumulator.rootContext());
+    ObjectValue updateData =
+        convertAndParseDocumentData(input, accumulator.rootContext(), expectedId);
 
     if (fieldMask != null) {
       // Verify that all elements specified in the field mask are part of the parsed context.
@@ -198,7 +214,7 @@ public FieldValue parseQueryValue(Object input) {
 
   /** Converts a POJO to native types and then parses it into model types. */
   private FieldValue convertAndParseFieldData(Object input, ParseContext context) {
-    Object converted = CustomClassMapper.convertToPlainJavaTypes(input);
+    Object converted = CustomClassMapper.withDocumentId(null).convertToPlainJavaTypes(input);
     return parseData(converted, context);
   }
 
@@ -207,7 +223,8 @@ private FieldValue convertAndParseFieldData(Object input, ParseContext context)
    * conform to document data (i.e. it must parse into an ObjectValue model type) and will throw an
    * appropriate error otherwise.
    */
-  private ObjectValue convertAndParseDocumentData(Object input, ParseContext context) {
+  private ObjectValue convertAndParseDocumentData(
+      Object input, ParseContext context, String expectedId) {
     String badDocReason =
         "Invalid data. Data must be a Map<String, Object> or a suitable POJO object, but it was ";
 
@@ -217,7 +234,7 @@ private ObjectValue convertAndParseDocumentData(Object input, ParseContext conte
       throw new IllegalArgumentException(badDocReason + "an array");
     }
 
-    Object converted = CustomClassMapper.convertToPlainJavaTypes(input);
+    Object converted = CustomClassMapper.withDocumentId(expectedId).convertToPlainJavaTypes(input);
     FieldValue value = parseData(converted, context);
 
     if (!(value instanceof ObjectValue)) {

firebase-firestore/src/main/java/com/google/firebase/firestore/WriteBatch.java

@@ -87,12 +87,13 @@ public WriteBatch set(
     firestore.validateReference(documentRef);
     checkNotNull(data, "Provided data must not be null.");
     checkNotNull(options, "Provided options must not be null.");
-    // TODO: Assert fields annotated with DocumentId in `data` match `documentRef`.
     verifyNotCommitted();
     ParsedSetData parsed =
         options.isMerge()
-            ? firestore.getDataConverter().parseMergeData(data, options.getFieldMask())
-            : firestore.getDataConverter().parseSetData(data);
+            ? firestore
+                .getDataConverter()
+                .parseMergeData(data, options.getFieldMask(), documentRef.getId())
+            : firestore.getDataConverter().parseSetData(data, documentRef.getId());
     mutations.addAll(parsed.toMutationList(documentRef.getKey(), Precondition.NONE));
     return this;
   }

firebase-firestore/src/main/java/com/google/firebase/firestore/util/CustomClassMapper.java

@@ -48,7 +48,6 @@
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
-import javax.annotation.Nullable;
 
 /** Helper class to convert to/from custom POJO classes and plain Java types. */
 public class CustomClassMapper {
@@ -67,18 +66,35 @@ private static void hardAssert(boolean assertion, String message) {
     }
   }
 
+  /**
+   * Returns a mapper with a given document ID. The document ID will be used to populate the {@link
+   * com.google.firebase.firestore.DocumentId} annotated fields of the POJO of the custom class;
+   * when converting a POJO to plain Java type, the @DocumentId-annotated fields should be either
+   * null or match the given document ID.
+   */
+  // TODO: actually implement documentId population/validation logic during (de)serialization.
+  public static CustomClassMapper withDocumentId(String documentId) {
+    return new CustomClassMapper(documentId);
+  }
+
+  private CustomClassMapper(String documentId) {
+    this.documentId = documentId;
+  }
+
+  private String documentId = null;
+
   /**
    * Converts a Java representation of JSON data to standard library Java data types: Map, Array,
    * String, Double, Integer and Boolean. POJOs are converted to Java Maps.
    *
    * @param object The representation of the JSON data
    * @return JSON representation containing only standard library Java types
    */
-  public static Object convertToPlainJavaTypes(Object object) {
+  public Object convertToPlainJavaTypes(Object object) {
     return serialize(object);
   }
 
-  public static Map<String, Object> convertToPlainJavaTypes(Map<?, Object> update) {
+  public Map<String, Object> convertToPlainJavaTypes(Map<?, Object> update) {
     Object converted = serialize(update);
     hardAssert(converted instanceof Map);
     @SuppressWarnings("unchecked")
@@ -94,25 +110,16 @@ public static Map<String, Object> convertToPlainJavaTypes(Map<?, Object> update)
    * @param clazz The class of the object to convert to
    * @return The POJO object.
    */
-  public static <T> T convertToCustomClass(Object object, Class<T> clazz) {
+  public <T> T convertToCustomClass(Object object, Class<T> clazz) {
     return deserializeToClass(object, clazz, ErrorPath.EMPTY);
   }
 
-  /**
-   * If there are fields annotated with {@link com.google.firebase.firestore.DocumentId}, make sure
-   * they are set to expected value by throwing runtime exception when it fails to comply.
-   *
-   * @param object Java object that might have DocumentId annotated fields.
-   * @param expected Expected value of the DocumentId annotated fields.
-   */
-  public static void assertAnnotatedDocumentIdEqual(Object object, @Nullable Object expected) {}
-
-  private static <T> Object serialize(T o) {
+  private <T> Object serialize(T o) {
     return serialize(o, ErrorPath.EMPTY);
   }
 
   @SuppressWarnings("unchecked")
-  private static <T> Object serialize(T o, ErrorPath path) {
+  private <T> Object serialize(T o, ErrorPath path) {
     if (path.getLength() > MAX_DEPTH) {
       throw serializeError(
           path,
@@ -182,7 +189,7 @@ private static <T> Object serialize(T o, ErrorPath path) {
     } else {
       Class<T> clazz = (Class<T>) o.getClass();
       BeanMapper<T> mapper = loadOrCreateBeanMapperForClass(clazz);
-      return mapper.serialize(o, path);
+      return mapper.serialize(o, path, this);
     }
   }
 
@@ -763,7 +770,7 @@ private Type resolveType(Type type, Map<TypeVariable<Class<T>>, Type> types) {
       }
     }
 
-    Map<String, Object> serialize(T object, ErrorPath path) {
+    Map<String, Object> serialize(T object, ErrorPath path, CustomClassMapper classMapper) {
       if (!clazz.isAssignableFrom(object.getClass())) {
         throw new IllegalArgumentException(
             "Can't serialize object of class "
@@ -795,7 +802,7 @@ Map<String, Object> serialize(T object, ErrorPath path) {
           // Replace null ServerTimestamp-annotated fields with the sentinel.
           serializedValue = FieldValue.serverTimestamp();
         } else {
-          serializedValue = CustomClassMapper.serialize(propertyValue, path.child(property));
+          serializedValue = classMapper.serialize(propertyValue, path.child(property));
         }
         result.put(property, serializedValue);
       }