fix: Exclude transient properties when false

FlagsmithClient/src/main/java/com/flagsmith/entities/IdentityAndTraits.kt

@@ -1,9 +1,27 @@
 package com.flagsmith.entities
 
+import com.google.gson.*
 import com.google.gson.annotations.SerializedName
+import java.lang.reflect.Type
 
 data class IdentityAndTraits(
     @SerializedName(value = "identifier") val identifier: String,
     @SerializedName(value = "traits") val traits: List<Trait>,
     @SerializedName(value = "transient") val transient: Boolean? = null
-)
+)
+
+class IdentityAndTraitsSerializer : JsonSerializer<IdentityAndTraits> {
+    override fun serialize(src: IdentityAndTraits, typeOfSrc: Type, context: JsonSerializationContext): JsonElement {
+        // Create a JsonObject with all fields except transient
+        val jsonObject = JsonObject()
+        jsonObject.addProperty("identifier", src.identifier)
+        jsonObject.add("traits", context.serialize(src.traits))
+
+        // Only add transient if it's true
+        if (src.transient == true) {
+            jsonObject.addProperty("transient", true)
+        }
+
+        return jsonObject
+    }
+}

FlagsmithClient/src/main/java/com/flagsmith/entities/Trait.kt

@@ -1,8 +1,8 @@
 package com.flagsmith.entities
 
-
+import com.google.gson.*
 import com.google.gson.annotations.SerializedName
-
+import java.lang.reflect.Type
 
 data class Trait (
     val identifier: String? = null,
@@ -46,6 +46,19 @@ data class Trait (
         get() = traitValue as? Boolean
 }
 
+class TraitSerializer : JsonSerializer<Trait> {
+    override fun serialize(src: Trait, typeOfSrc: Type, context: JsonSerializationContext): JsonElement {
+        val jsonObject = JsonObject()
+        src.identifier?.let { jsonObject.addProperty("identifier", it) }
+        jsonObject.addProperty("trait_key", src.key)
+        jsonObject.addProperty("trait_value", src.traitValue.toString())
+        if (src.transient) {
+            jsonObject.addProperty("transient", true)
+        }
+        return jsonObject
+    }
+}
+
 data class TraitWithIdentity (
     @SerializedName(value = "trait_key") val key: String,
     @SerializedName(value = "trait_value") val traitValue: Any,

FlagsmithClient/src/main/java/com/flagsmith/internal/FlagsmithRetrofitService.kt

@@ -5,7 +5,10 @@ import android.util.Log
 import com.flagsmith.FlagsmithCacheConfig
 import com.flagsmith.entities.Flag
 import com.flagsmith.entities.IdentityAndTraits
+import com.flagsmith.entities.IdentityAndTraitsSerializer
 import com.flagsmith.entities.IdentityFlagsAndTraits
+import com.flagsmith.entities.Trait
+import com.flagsmith.entities.TraitSerializer
 import okhttp3.Cache
 import okhttp3.Interceptor
 import okhttp3.OkHttpClient
@@ -15,6 +18,7 @@ import retrofit2.http.Body
 import retrofit2.http.GET
 import retrofit2.http.POST
 import retrofit2.http.Query
+import com.google.gson.GsonBuilder
 
 interface FlagsmithRetrofitService {
 
@@ -97,9 +101,14 @@ interface FlagsmithRetrofitService {
                 .cache(cache)
                 .build()
 
+            val gson = GsonBuilder()
+                .registerTypeAdapter(IdentityAndTraits::class.java, IdentityAndTraitsSerializer())
+                .registerTypeAdapter(Trait::class.java, TraitSerializer())
+                .create()
+
             val retrofit = Retrofit.Builder()
                 .baseUrl(baseUrl)
-                .addConverterFactory(GsonConverterFactory.create())
+                .addConverterFactory(GsonConverterFactory.create(gson))
                 .client(client)
                 .build()
 

FlagsmithClient/src/test/java/com/flagsmith/FeatureFlagTests.kt

@@ -182,11 +182,9 @@ class FeatureFlagTests {
                                 },
                                 {
                                   "trait_key": "persisted-trait",
-                                  "trait_value": "value",
-                                  "transient": false
+                                  "trait_value": "value"
                                 }
-                              ],
-                              "transient": false
+                              ]
                             }
                         """.trimIndent()
                     )

FlagsmithClient/src/test/java/com/flagsmith/entities/SerializerTests.kt

@@ -0,0 +1,82 @@
+package com.flagsmith.entities
+
+import com.google.gson.GsonBuilder
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class SerializerTests {
+    private val gson = GsonBuilder()
+        .registerTypeAdapter(IdentityAndTraits::class.java, IdentityAndTraitsSerializer())
+        .registerTypeAdapter(Trait::class.java, TraitSerializer())
+        .create()
+
+    @Test
+    fun `IdentityAndTraitsSerializer omits transient field when false`() {
+        val identity = IdentityAndTraits(
+            identifier = "test-user",
+            traits = listOf(Trait("key", "value")),
+            transient = false
+        )
+
+        val json = gson.toJson(identity)
+        assertEquals(
+            """{"identifier":"test-user","traits":[{"trait_key":"key","trait_value":"value"}]}""",
+            json
+        )
+    }
+
+    @Test
+    fun `IdentityAndTraitsSerializer includes transient field when true`() {
+        val identity = IdentityAndTraits(
+            identifier = "test-user",
+            traits = listOf(Trait("key", "value")),
+            transient = true
+        )
+
+        val json = gson.toJson(identity)
+        assertEquals(
+            """{"identifier":"test-user","traits":[{"trait_key":"key","trait_value":"value"}],"transient":true}""",
+            json
+        )
+    }
+
+    @Test
+    fun `TraitSerializer omits transient field when false`() {
+        val trait = Trait("key", "value", false)
+        val json = gson.toJson(trait)
+        assertEquals(
+            """{"trait_key":"key","trait_value":"value"}""",
+            json
+        )
+    }
+
+    @Test
+    fun `TraitSerializer includes transient field when true`() {
+        val trait = Trait("key", "value", true)
+        val json = gson.toJson(trait)
+        assertEquals(
+            """{"trait_key":"key","trait_value":"value","transient":true}""",
+            json
+        )
+    }
+
+    @Test
+    fun `TraitSerializer handles optional identifier`() {
+        val traitWithId = Trait(
+            identifier = "test-id",
+            key = "key",
+            traitValue = "value",
+            transient = false
+        )
+        val traitWithoutId = Trait("key", "value", false)
+
+        assertEquals(
+            """{"identifier":"test-id","trait_key":"key","trait_value":"value"}""",
+            gson.toJson(traitWithId)
+        )
+        assertEquals(
+            """{"trait_key":"key","trait_value":"value"}""",
+            gson.toJson(traitWithoutId)
+        )
+    }
+}