Support for arbitrary classes in EvaluationContext

Author: justinabrahms

lib/build.gradle

@@ -26,6 +26,8 @@ repositories {
 
 dependencies {
     implementation 'org.slf4j:slf4j-log4j12:1.7.29'
+    implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.0'
+
     // This dependency is used internally, and not exposed to consumers on their own compile classpath.
     implementation 'com.google.guava:guava:30.1.1-jre'
 

lib/src/main/java/dev/openfeature/javasdk/EvaluationContext.java

@@ -1,9 +1,7 @@
 package dev.openfeature.javasdk;
 
-import lombok.EqualsAndHashCode;
-import lombok.Getter;
-import lombok.Setter;
-import lombok.ToString;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.*;
 
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
@@ -13,14 +11,32 @@
 @ToString @EqualsAndHashCode
 @SuppressWarnings("PMD.BeanMembersShouldSerialize")
 public class EvaluationContext {
+    @EqualsAndHashCode.Exclude private final ObjectMapper objMapper;
     @Setter @Getter private String targetingKey;
     private final Map<String, Integer> integerAttributes;
     private final Map<String, String> stringAttributes;
+    private final Map<String, Boolean> booleanAttributes;
+    final Map<String, String> jsonAttributes;
 
     EvaluationContext() {
+        objMapper = new ObjectMapper();
         this.targetingKey = "";
         this.integerAttributes = new HashMap<>();
         this.stringAttributes = new HashMap<>();
+        booleanAttributes = new HashMap<>();
+        jsonAttributes = new HashMap<>();
+    }
+
+    // TODO Not sure if I should have sneakythrows or checked exceptions here..
+    @SneakyThrows
+    public <T> void addStructureAttribute(String key, T value) {
+        jsonAttributes.put(key, objMapper.writeValueAsString(value));
+    }
+
+    @SneakyThrows
+    public <T> T getStructureAttribute(String key, Class<T> klass) {
+        String val = jsonAttributes.get(key);
+        return objMapper.readValue(val, klass);
     }
 
     public void addStringAttribute(String key, String value) {
@@ -40,19 +56,17 @@ public Integer getIntegerAttribute(String key) {
     }
 
     public Boolean getBooleanAttribute(String key) {
-        return Boolean.valueOf(stringAttributes.get(key));
+        return booleanAttributes.get(key);
     }
 
     public void addBooleanAttribute(String key, Boolean b) {
-        stringAttributes.put(key, b.toString());
+        booleanAttributes.put(key, b);
     }
 
     public void addDatetimeAttribute(String key, ZonedDateTime value) {
         this.stringAttributes.put(key, value.format(DateTimeFormatter.ISO_ZONED_DATE_TIME));
     }
 
-    // TODO: addStructure or similar.
-
     public ZonedDateTime getDatetimeAttribute(String key) {
         String attr = this.stringAttributes.get(key);
         if (attr == null) {
@@ -66,21 +80,19 @@ public ZonedDateTime getDatetimeAttribute(String key) {
      */
     public static EvaluationContext merge(EvaluationContext ctx1, EvaluationContext ctx2) {
         EvaluationContext ec = new EvaluationContext();
-        for (Map.Entry<String, Integer> e : ctx1.integerAttributes.entrySet()) {
-            ec.addIntegerAttribute(e.getKey(), e.getValue());
-        }
 
-        for (Map.Entry<String, Integer> e : ctx2.integerAttributes.entrySet()) {
-            ec.addIntegerAttribute(e.getKey(), e.getValue());
-        }
+        ec.stringAttributes.putAll(ctx1.stringAttributes);
+        ec.stringAttributes.putAll(ctx2.stringAttributes);
 
-        for (Map.Entry<String, String> e : ctx1.stringAttributes.entrySet()) {
-            ec.addStringAttribute(e.getKey(), e.getValue());
-        }
+        ec.integerAttributes.putAll(ctx1.integerAttributes);
+        ec.integerAttributes.putAll(ctx2.integerAttributes);
+
+        ec.booleanAttributes.putAll(ctx1.booleanAttributes);
+        ec.booleanAttributes.putAll(ctx2.booleanAttributes);
+
+        ec.jsonAttributes.putAll(ctx1.jsonAttributes);
+        ec.jsonAttributes.putAll(ctx2.jsonAttributes);
 
-        for (Map.Entry<String, String> e : ctx2.stringAttributes.entrySet()) {
-            ec.addStringAttribute(e.getKey(), e.getValue());
-        }
         if (ctx1.getTargetingKey() != null) {
             ec.setTargetingKey(ctx1.getTargetingKey());
         }

lib/src/test/java/dev/openfeature/javasdk/EvalContextTests.java

@@ -1,6 +1,5 @@
 package dev.openfeature.javasdk;
 
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import java.time.ZonedDateTime;
@@ -40,6 +39,24 @@ public class EvalContextTests {
     @Specification(spec="Evaluation Context", number="3.2", text="The evaluation context MUST support the inclusion of " +
             "custom fields, having keys of type `string`, and " +
             "values of type `boolean | string | number | datetime | structure`.")
-    @Disabled("Structure support")
-    @Test void eval_context__structure() {}
+    @Test void eval_context__structure() {
+        Node<Integer> n1 = new Node<>();
+        n1.value = 4;
+        Node<Integer> n2 = new Node<>();
+        n2.value = 2;
+        n2.left = n1;
+
+        EvaluationContext ec = new EvaluationContext();
+        ec.addStructureAttribute("obj", n2);
+
+
+        String stringyObject = ec.jsonAttributes.get("obj");
+        assertEquals("{\"left\":{\"left\":null,\"right\":null,\"value\":4},\"right\":null,\"value\":2}", stringyObject);
+
+        Node nodeFromString = ec.getStructureAttribute("obj", Node.class);
+        assertEquals(n2, nodeFromString);
+        assertEquals(n1, nodeFromString.left);
+        assertEquals(2, nodeFromString.value);
+        assertEquals(4, nodeFromString.left.value);
+    }
 }

lib/src/test/java/dev/openfeature/javasdk/Node.java

@@ -0,0 +1,12 @@
+package dev.openfeature.javasdk;
+
+import lombok.Data;
+
+@Data
+/**
+ * This is only for testing that object serialization works with both generics and nested classes.
+ */
+class Node<T> {
+    Node<T> left, right;
+    T value;
+}