Don't output traits if they are empty.

Author: bsneed

Examples/other_plugins/InjectTraits.swift

@@ -44,7 +44,9 @@ class InjectTraits: Plugin {
         var workingEvent = event
 
         if var context = event?.context?.dictionaryValue {
-            context[keyPath: "traits"] = analytics?.traits()
+            if let traits = analytics?.traits() {
+                context[keyPath: "traits"] = analytics?.traits()
+            }
 
             workingEvent?.context = try? JSON(context)
         }

Package.resolved

@@ -70,7 +70,7 @@ public struct IdentifyEvent: RawEvent {
     public var metrics: [JSON]? = nil
     public var _metadata: DestinationMetadata? = nil
 
-    public var traits: JSON?
+    @OmitIfNull public var traits: JSON?
 
 
     public init(userId: String? = nil, traits: JSON? = nil) {

Sources/Segment/Types.swift

@@ -0,0 +1,32 @@
+//
+//  OmitIfNull.swift
+//  Segment
+//
+//  Created by Brandon Sneed on 3/11/25.
+//
+
+@propertyWrapper
+public struct OmitIfNull<T: Codable>: Codable {
+    public var wrappedValue: T?
+    
+    public init(wrappedValue: T?) {
+        self.wrappedValue = wrappedValue
+    }
+    
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.singleValueContainer()
+        if let value = wrappedValue {
+            try container.encode(value)
+        } else {
+            try container.encodeNil()
+        }
+    }
+}
+
+extension KeyedEncodingContainer {
+    internal mutating func encode<T>(_ value: OmitIfNull<T>, forKey key: Key) throws where T: Encodable {
+        if value.wrappedValue != nil {
+            try encode(value.wrappedValue, forKey: key)
+        }
+    }
+}

Sources/Segment/Utilities/OmitIfNull.swift

@@ -360,6 +360,33 @@ final class Analytics_Tests: XCTestCase {
         let traits = identifyEvent?.traits?.dictionaryValue
         XCTAssertTrue(traits?["email"] as? String == "blah@blah.com")
     }
+    
+    func testTraitsNull() {
+        let analytics = Analytics(configuration: Configuration(writeKey: "test"))
+        let outputReader = OutputReaderPlugin()
+        analytics.add(plugin: outputReader)
+        
+        waitUntilStarted(analytics: analytics)
+        
+        analytics.identify(userId: "brandon", traits: nil)
+        
+        let identifyEvent: IdentifyEvent? = outputReader.lastEvent as? IdentifyEvent
+        
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = .prettyPrinted  // Makes the JSON nice and readable
+
+        let jsonNoTraits = try! encoder.encode(identifyEvent)
+        let jsonNoTraitsString = String(data: jsonNoTraits, encoding: .utf8)!
+        
+        XCTAssertFalse(jsonNoTraitsString.contains("\"traits\""))
+        
+        analytics.identify(userId: "brandon", traits: ["some": "value"])
+        let identifyEventTraits: IdentifyEvent? = outputReader.lastEvent as? IdentifyEvent
+        let jsonWithTraits = try! encoder.encode(identifyEventTraits)
+        let jsonWithTraitsString = String(data: jsonWithTraits, encoding: .utf8)!
+        
+        XCTAssertTrue(jsonWithTraitsString.contains("\"traits\""))
+    }
 
     func testUserIdAndTraitsPersistCorrectly() {
         let analytics = Analytics(configuration: Configuration(writeKey: "test"))