[json-node] Fix NULL value bug with JsonObject (#322)

* [json-node] Fix NULL value bug with JsonObject

Also fix DecimalAdapter

* [json-node] Add JsonObject.extractOrEmpty() methods

Returning Optional especially for String values mapping to other types.

Author: rbygrave

json-node/src/main/java/io/avaje/json/node/JsonNode.java

@@ -3,6 +3,7 @@
 import org.jspecify.annotations.Nullable;
 
 import java.io.Serializable;
+import java.util.Optional;
 
 /**
  * Represents the core JSON types.
@@ -107,6 +108,13 @@ default String extract(String path) {
     throw new UnsupportedOperationException();
   }
 
+  /**
+   * Extract the text from the given path if present else empty.
+   */
+  default Optional<String> extractOrEmpty(String path) {
+    throw new UnsupportedOperationException();
+  }
+
   /**
    * Extract the text from the given path if present or the given default value.
    *
@@ -172,4 +180,13 @@ default JsonNode extractNode(String path, JsonNode missingValue) {
     throw new UnsupportedOperationException();
   }
 
+  /**
+   * Extract the node from the given path if present else empty.
+   *
+   * @return The node for the given path.
+   */
+  default Optional<JsonNode> extractNodeOrEmpty(String path) {
+    throw new UnsupportedOperationException();
+  }
+
 }

json-node/src/main/java/io/avaje/json/node/JsonObject.java

@@ -2,10 +2,7 @@
 
 import org.jspecify.annotations.Nullable;
 
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
 import java.util.regex.Pattern;
 
 import static java.util.Objects.requireNonNull;
@@ -220,6 +217,12 @@ public String extract(String path) {
     return node.text();
   }
 
+  @Override
+  public Optional<String> extractOrEmpty(String path) {
+    final var name = find(path);
+    return name == null ? Optional.empty() : Optional.of(name.text());
+  }
+
   @Override
   public String extract(String path, String missingValue) {
     final var name = find(path);
@@ -272,4 +275,10 @@ public JsonNode extractNode(String path, JsonNode missingValue) {
     final var node = find(path);
     return node != null ? node : missingValue;
   }
+
+  @Override
+  public Optional<JsonNode> extractNodeOrEmpty(String path) {
+    final var node = find(path);
+    return Optional.ofNullable(node);
+  }
 }

json-node/src/main/java/io/avaje/json/node/adapter/DecimalAdapter.java

@@ -3,17 +3,17 @@
 import io.avaje.json.JsonAdapter;
 import io.avaje.json.JsonReader;
 import io.avaje.json.JsonWriter;
-import io.avaje.json.node.JsonLong;
+import io.avaje.json.node.JsonDecimal;
 
-final class DecimalAdapter implements JsonAdapter<JsonLong> {
+final class DecimalAdapter implements JsonAdapter<JsonDecimal> {
 
   @Override
-  public void toJson(JsonWriter writer, JsonLong value) {
-    writer.value(value.longValue());
+  public void toJson(JsonWriter writer, JsonDecimal value) {
+    writer.value(value.decimalValue());
   }
 
   @Override
-  public JsonLong fromJson(JsonReader reader) {
-    return JsonLong.of(reader.readLong());
+  public JsonDecimal fromJson(JsonReader reader) {
+    return JsonDecimal.of(reader.readDecimal());
   }
 }

json-node/src/main/java/io/avaje/json/node/adapter/NodeAdapter.java

@@ -33,6 +33,7 @@ ObjectAdapter objectAdapter() {
   public JsonNode fromJson(JsonReader reader) {
     switch (reader.currentToken()) {
       case NULL:
+        reader.isNullValue();
         return null;
       case BEGIN_ARRAY:
         return arrayAdapter.fromJson(reader);
@@ -55,8 +56,7 @@ public void toJson(JsonWriter writer, JsonNode value) {
       writer.nullValue();
       return;
     }
-    JsonNode.Type type = value.type();
-    switch (type) {
+    switch (value.type()) {
       case NULL:
         writer.nullValue();
         break;

json-node/src/test/java/io/avaje/json/node/ExtractNodeTest.java

@@ -75,6 +75,16 @@ void extract() {
 
     assertThat(missingOther).hasSize(2);
     assertThat(missingOther).containsExactly("BOther", "MISSING!");
+
+    List<String> missingOther2 =
+      arrayWithNestedPerson.stream()
+        .filter(node -> "family".equals(node.extract("type")))
+        .flatMap(node -> node.extractNodeOrEmpty("person.other").stream())
+        .map(JsonNode::text)
+        .collect(Collectors.toList());
+
+    assertThat(missingOther2).hasSize(1);
+    assertThat(missingOther2).containsExactly("BOther");
   }
 
   @Test

json-node/src/test/java/io/avaje/json/node/JsonObjectTest.java

@@ -19,7 +19,7 @@ class JsonObjectTest {
 
   @Test
   void of() {
-    Map<String,JsonNode> map = new LinkedHashMap<>();
+    Map<String, JsonNode> map = new LinkedHashMap<>();
     map.put("name", JsonString.of("foo"));
     map.put("other", JsonInteger.of(42));
 
@@ -141,6 +141,9 @@ void findNested() {
     assertThat(node.extract("person.active", false)).isEqualTo(true);
     assertThat(node.extract("person.missing", false)).isEqualTo(false);
 
+    assertThat(node.extractOrEmpty("person.missing")).isEmpty();
+    assertThat(node.extractOrEmpty("person.name")).isNotEmpty().asString().contains("myName");
+
     assertThat(node.extract("address.size", -1)).isEqualTo(42);
     assertThat(node.extract("address.junk", -1L)).isEqualTo(99L);
     assertThat(node.extract("address.notSize", -1)).isEqualTo(-1);
@@ -190,4 +193,13 @@ void toPlain() {
     assertThat(plainMap.get("name")).isEqualTo("foo");
     assertThat(plainMap.get("other")).isEqualTo(Map.of("b", 42));
   }
+
+  @Test
+  void nullValuesInMap() {
+    String s = "{\"a\":1,\"b\":null,\"c\":null,\"d\":4}";
+    JsonNodeMapper mapper = JsonNodeMapper.builder().build();
+    JsonObject jsonObject = mapper.fromJsonObject(s);
+
+    assertThat(jsonObject.elements().keySet()).containsExactly("a", "b", "c", "d");
+  }
 }

json-node/src/test/java/io/avaje/json/node/adapter/JsonNodeAdaptersTest.java

@@ -3,9 +3,11 @@
 import io.avaje.json.JsonAdapter;
 import io.avaje.json.JsonReader;
 import io.avaje.json.node.*;
+import io.avaje.json.simple.SimpleMapper;
 import io.avaje.json.stream.JsonStream;
 import org.junit.jupiter.api.Test;
 
+import java.math.BigDecimal;
 import java.time.LocalDate;
 import java.util.List;
 
@@ -67,9 +69,15 @@ void create_JsonDouble_expect_sameInstance() {
 
   @Test
   void create_JsonDecimal_expect_sameInstance() {
-    JsonAdapter<?> jsonAdapter = mapper.adapter(JsonDecimal.class);
+    JsonAdapter<JsonDecimal> jsonAdapter = mapper.adapter(JsonDecimal.class);
     JsonAdapter<JsonDecimal> adapter = mapper.adapter(JsonDecimal.class);
     assertThat(jsonAdapter).isSameAs(adapter);
+
+    SimpleMapper.Type<JsonDecimal> type = mapper.type(jsonAdapter);
+
+    String asJson1 = type.toJson(JsonDecimal.of(new BigDecimal("23.45")));
+    assertThat(asJson1).isEqualTo("23.45");
+    assertThat(type.fromJson(asJson1)).isEqualTo(JsonDecimal.of(new BigDecimal("23.45")));
   }
 
   @Test