QueryVal, Query Composition, and circular ref bug fixes

src/main/java/com/fauna/codec/DefaultCodecProvider.java

@@ -12,10 +12,12 @@
 import com.fauna.codec.codecs.QueryCodec;
 import com.fauna.codec.codecs.QueryLiteralCodec;
 import com.fauna.codec.codecs.QueryObjCodec;
+import com.fauna.codec.codecs.QueryValCodec;
 import com.fauna.query.builder.Query;
 import com.fauna.query.builder.QueryArr;
 import com.fauna.query.builder.QueryLiteral;
 import com.fauna.query.builder.QueryObj;
+import com.fauna.query.builder.QueryVal;
 import com.fauna.types.BaseDocument;
 import com.fauna.types.Document;
 import com.fauna.types.NamedDocument;
@@ -38,6 +40,7 @@ public DefaultCodecProvider(CodecRegistry registry) {
         registry.put(CodecRegistryKey.from(Query.class), new QueryCodec(this));
         registry.put(CodecRegistryKey.from(QueryObj.class), new QueryObjCodec(this));
         registry.put(CodecRegistryKey.from(QueryArr.class), new QueryArrCodec(this));
+        registry.put(CodecRegistryKey.from(QueryVal.class), new QueryValCodec(this));
         registry.put(CodecRegistryKey.from(QueryLiteral.class), new QueryLiteralCodec());
 
         var bdc = new BaseDocumentCodec(this);

src/main/java/com/fauna/codec/codecs/ClassCodec.java

@@ -47,8 +47,8 @@ public ClassCodec(Class<T> ty, CodecProvider provider) {
             }
 
             var ta = attr.typeArgument() != void.class ? attr.typeArgument() : null;
-            var codec = provider.get(field.getType(), ta);
-            FieldInfo info = new FieldInfo(field, attr.name(), codec);
+            // Don't init the codec here because of potential circular references; instead use a provider.
+            FieldInfo info = new FieldInfo(field, attr.name(), ta, provider);
             fieldsList.add(info);
             byNameMap.put(info.getName(), info);
         }
@@ -86,7 +86,7 @@ public void encode(UTF8FaunaGenerator gen, T obj) throws IOException {
                 try {
                     fi.getProperty().setAccessible(true);
                     @SuppressWarnings("unchecked")
-                    T value = (T) fi.getProperty().get(obj);
+                    T value = obj != null ? (T) fi.getProperty().get(obj) : null;
                     @SuppressWarnings("unchecked")
                     Codec<T> codec = fi.getCodec();
                     codec.encode(gen, value);

src/main/java/com/fauna/mapping/FieldInfo.java

@@ -1,21 +1,23 @@
 package com.fauna.mapping;
 
 import com.fauna.codec.Codec;
+import com.fauna.codec.CodecProvider;
 
 import java.lang.reflect.Field;
 
 public final class FieldInfo {
 
     private final String name;
     private final Field property;
-    private final Class<?> type;
+    private final Class<?> typeArg;
+    private final CodecProvider provider;
     private Codec<?> codec;
 
-    public FieldInfo(Field prop, String name, Codec codec) {
+    public FieldInfo(Field prop, String name, Class<?> typeArg, CodecProvider provider) {
         this.name = name;
         this.property = prop;
-        this.type = prop.getType();
-        this.codec = codec;
+        this.typeArg = typeArg;
+        this.provider = provider;
     }
 
     public String getName() {
@@ -27,10 +29,19 @@ public Field getProperty() {
     }
 
     public Class<?> getType() {
-        return type;
+        return property.getType();
     }
 
     public Codec getCodec() {
-        return this.codec;
+        if (codec != null) return codec;
+
+        synchronized (this) {
+            // check again in case it was set by another thread
+            if (codec != null) return codec;
+
+            codec = provider.get(property.getType(), typeArg);
+        }
+
+        return codec;
     }
 }

src/main/java/com/fauna/query/builder/Query.java

@@ -1,10 +1,7 @@
 package com.fauna.query.builder;
 
-import com.fauna.codec.CodecProvider;
 import com.fauna.query.template.FaunaTemplate;
-import com.fauna.codec.UTF8FaunaGenerator;
 
-import java.io.IOException;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Spliterator;
@@ -15,7 +12,7 @@
  * Represents a Fauna query that is constructed from fragments.
  * This class allows the building of queries from literal and variable parts.
  */
-public class Query{
+public class Query extends QueryFragment<QueryFragment[]> {
 
     private final QueryFragment[] fql;
 
@@ -62,9 +59,10 @@ public static Query fql(String query) throws IllegalArgumentException {
     /**
      * Retrieves the list of fragments that make up this query.
      *
-     * @return a list of Fragments.
+     * @return an array of Fragments.
      * @throws IllegalArgumentException if a template variable does not have a corresponding entry in the provided args.
      */
+    @Override
     public QueryFragment[] get() {
         return this.fql;
     }

src/test/java/com/fauna/beans/Circular.java

@@ -0,0 +1,9 @@
+package com.fauna.beans;
+
+public class Circular {
+    public static class Inner {
+        public Circular outer;
+    }
+
+    public Inner inner;
+}

src/test/java/com/fauna/codec/DefaultCodecProviderTest.java

@@ -1,5 +1,6 @@
 package com.fauna.codec;
 
+import com.fauna.beans.Circular;
 import org.junit.jupiter.api.Test;
 
 import java.util.List;
@@ -44,4 +45,12 @@ public void get_generatesListCodecForImmutableList() {
         assertNotNull(codec);
         assertEquals(List.class, codec.getCodecClass());
     }
+
+    @Test
+    @SuppressWarnings({"rawtypes", "unchecked"})
+    public void get_generateForClassWithCircularRef() {
+        Codec<Circular> codec = cp.get(Circular.class, null);
+        assertNotNull(codec);
+        assertEquals(Circular.class, codec.getCodecClass());
+    }
 }

src/test/java/com/fauna/query/builder/QueryTest.java

@@ -77,15 +77,15 @@ public void testQueryBuilderValues() {
     }
 
     @Test
-    public void testQueryBuilderSubQueries() {
+    public void testQueryBuilderSubQueries() throws IOException {
         Map<String, Object> user = Map.of(
                 "name", "Dino",
                 "age", 0,
                 "birthdate", LocalDate.of(2023, 2, 24));
 
         Query inner = fql("let x = ${my_var}", Map.of("my_var", user));
         Query actual = fql("${inner}\nx { name }", Map.of("inner", inner));
-        QueryFragment[] expected = new QueryFragment[]{new QueryVal(inner), new QueryLiteral("\nx { name }")};
+        QueryFragment[] expected = new QueryFragment[]{inner, new QueryLiteral("\nx { name }")};
         assertArrayEquals(expected, actual.get());
     }