chore: Support the propertiesSanitizer config

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## Next
 
+- chore: Support the `propertiesSanitizer` config ([#154](https://github.com/PostHog/posthog-ios/pull/154))
+
 ## 3.6.3 - 2024-07-26
 
 - recording: fix: respect session replay project settings from app start ([#150](https://github.com/PostHog/posthog-ios/pull/150))

PostHog.xcodeproj/project.pbxproj

@@ -67,6 +67,8 @@
 		69278D472AE6BC7200BB541A /* main.m in Sources */ = {isa = PBXBuildFile; fileRef = 69278D462AE6BC7200BB541A /* main.m */; };
 		69278D4B2AE6BC9000BB541A /* PostHog.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3AC745B5296D6FE60025C109 /* PostHog.framework */; };
 		69278D4C2AE6BC9000BB541A /* PostHog.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 3AC745B5296D6FE60025C109 /* PostHog.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		693E977B2C625208004B1030 /* PostHogPropertiesSanitizer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 693E977A2C625208004B1030 /* PostHogPropertiesSanitizer.swift */; };
+		693E977D2C6257F9004B1030 /* ExampleSanitizer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 693E977C2C6257F9004B1030 /* ExampleSanitizer.swift */; };
 		6955CB732C517651008EFD8D /* CGSize+Util.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6955CB722C517651008EFD8D /* CGSize+Util.swift */; };
 		69779BEC2AE68E6900D7A48E /* UIViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 69779BEB2AE68E6900D7A48E /* UIViewController.swift */; };
 		6992AA832AFE51A000087600 /* PostHogExampleTvOSApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6992AA822AFE51A000087600 /* PostHogExampleTvOSApp.swift */; };
@@ -316,6 +318,8 @@
 		69278D432AE6BC7200BB541A /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
 		69278D452AE6BC7200BB541A /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		69278D462AE6BC7200BB541A /* main.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = main.m; sourceTree = "<group>"; };
+		693E977A2C625208004B1030 /* PostHogPropertiesSanitizer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogPropertiesSanitizer.swift; sourceTree = "<group>"; };
+		693E977C2C6257F9004B1030 /* ExampleSanitizer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ExampleSanitizer.swift; sourceTree = "<group>"; };
 		6955CB722C517651008EFD8D /* CGSize+Util.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "CGSize+Util.swift"; sourceTree = "<group>"; };
 		69779BEB2AE68E6900D7A48E /* UIViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIViewController.swift; sourceTree = "<group>"; };
 		6992AA802AFE51A000087600 /* PostHogExampleTvOS.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = PostHogExampleTvOS.app; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -541,6 +545,7 @@
 				69779BEB2AE68E6900D7A48E /* UIViewController.swift */,
 				690FF0C42AEFAE8200A0B06B /* PostHogLegacyQueue.swift */,
 				69F518372BB2BA0100F52C14 /* PostHogSwizzler.swift */,
+				693E977A2C625208004B1030 /* PostHogPropertiesSanitizer.swift */,
 			);
 			path = PostHog;
 			sourceTree = "<group>";
@@ -559,6 +564,7 @@
 				690FF0E82AEFD3BD00A0B06B /* PostHogQueueTest.swift */,
 				690FF0F42AF0F06100A0B06B /* PostHogSDKTest.swift */,
 				699C5FEE2C20242A007DB818 /* UUIDTest.swift */,
+				693E977C2C6257F9004B1030 /* ExampleSanitizer.swift */,
 			);
 			path = PostHogTests;
 			sourceTree = "<group>";
@@ -1080,6 +1086,7 @@
 				69F5181A2BAC81FC00F52C14 /* UITextInputTraits+Util.swift in Sources */,
 				69F517E82BAC675800F52C14 /* RRWireframe.swift in Sources */,
 				3A0F108529C9ABB6002C0084 /* ReadWriteLock.swift in Sources */,
+				693E977B2C625208004B1030 /* PostHogPropertiesSanitizer.swift in Sources */,
 				3AE3FB3D29924E8200AFFC18 /* PostHogSDK.swift in Sources */,
 				69F517F32BAC734300F52C14 /* UIColor+Util.swift in Sources */,
 				3AE3FB3F29924F4F00AFFC18 /* PostHogConfig.swift in Sources */,
@@ -1114,6 +1121,7 @@
 				690FF0BB2AEF8B8200A0B06B /* PostHogContextTest.swift in Sources */,
 				690FF0E32AEFD12900A0B06B /* PostHogConfigTest.swift in Sources */,
 				3A62647129CAF67B007E8C07 /* PostHogSessionManagerTest.swift in Sources */,
+				693E977D2C6257F9004B1030 /* ExampleSanitizer.swift in Sources */,
 				690FF0DF2AEFBC5700A0B06B /* PostHogLegacyQueueTest.swift in Sources */,
 				690FF0BD2AEF93F400A0B06B /* PostHogFeatureFlagsTest.swift in Sources */,
 				690FF0E92AEFD3BD00A0B06B /* PostHogQueueTest.swift in Sources */,

PostHog/PostHogConfig.swift

@@ -27,6 +27,10 @@ import Foundation
     @objc public var debug: Bool = false
     @objc public var optOut: Bool = false
     @objc public var getAnonymousId: ((UUID) -> UUID) = { uuid in uuid }
+    /// Hook that allows to sanitize the event properties
+    /// The hook is called before the event is cached or sent over the wire
+    @objc public var propertiesSanitizer: PostHogPropertiesSanitizer?
+
     /// Internal
     var snapshotEndpoint: String = "/s/"
 

PostHog/PostHogPropertiesSanitizer.swift

@@ -0,0 +1,34 @@
+//
+//  PostHogPropertiesSanitizer.swift
+//  PostHog
+//
+//  Created by Manoel Aranda Neto on 06.08.24.
+//
+
+import Foundation
+
+/// Protocol to sanitize the event properties
+@objc(PostHogPropertiesSanitizer) public protocol PostHogPropertiesSanitizer {
+    /// Sanitizes the event properties
+    /// - Parameter properties: the event properties to sanitize
+    /// - Returns: the sanitized properties
+    ///
+    /// Obs: `inout` cannot be used in Swift protocols, so you need to clone the properties
+    ///
+    /// ```swift
+    /// private class ExampleSanitizer: PostHogPropertiesSanitizer {
+    ///     public func sanitize(_ properties: [String: Any]) -> [String: Any] {
+    ///         var sanitizedProperties = properties
+    ///         // Perform sanitization
+    ///         // For example, removing keys with empty values
+    ///         for (key, value) in properties {
+    ///             if let stringValue = value as? String, stringValue.isEmpty {
+    ///                 sanitizedProperties.removeValue(forKey: key)
+    ///             }
+    ///         }
+    ///         return sanitizedProperties
+    ///     }
+    /// }
+    /// ```
+    @objc func sanitize(_ properties: [String: Any]) -> [String: Any]
+}

PostHog/PostHogSDK.swift

@@ -379,13 +379,16 @@ private let sessionChangeThreshold: TimeInterval = 60 * 30
         }
         let oldDistinctId = getDistinctId()
 
+        let properties = buildProperties(distinctId: distinctId, properties: [
+            "distinct_id": distinctId,
+            "$anon_distinct_id": getAnonymousId(),
+        ], userProperties: sanitizeDicionary(userProperties), userPropertiesSetOnce: sanitizeDicionary(userPropertiesSetOnce))
+        let sanitizedProperties = sanitizeProperties(properties)
+
         queue.add(PostHogEvent(
             event: "$identify",
             distinctId: distinctId,
-            properties: buildProperties(distinctId: distinctId, properties: [
-                "distinct_id": distinctId,
-                "$anon_distinct_id": getAnonymousId(),
-            ], userProperties: sanitizeDicionary(userProperties), userPropertiesSetOnce: sanitizeDicionary(userPropertiesSetOnce))
+            properties: sanitizedProperties
         ))
 
         if distinctId != oldDistinctId {
@@ -469,15 +472,19 @@ private let sessionChangeThreshold: TimeInterval = 60 * 30
         }
 
         let distinctId = getDistinctId()
+
+        let properties = buildProperties(distinctId: distinctId,
+                                         properties: sanitizeDicionary(properties),
+                                         userProperties: sanitizeDicionary(userProperties),
+                                         userPropertiesSetOnce: sanitizeDicionary(userPropertiesSetOnce),
+                                         groups: groups,
+                                         appendSharedProps: !snapshotEvent)
+        let sanitizedProperties = sanitizeProperties(properties)
+
         let posthogEvent = PostHogEvent(
             event: event,
             distinctId: distinctId,
-            properties: buildProperties(distinctId: distinctId,
-                                        properties: sanitizeDicionary(properties),
-                                        userProperties: sanitizeDicionary(userProperties),
-                                        userPropertiesSetOnce: sanitizeDicionary(userPropertiesSetOnce),
-                                        groups: groups,
-                                        appendSharedProps: !snapshotEvent)
+            properties: sanitizedProperties
         )
 
         // Replay has its own queue
@@ -515,13 +522,24 @@ private let sessionChangeThreshold: TimeInterval = 60 * 30
         ].merging(sanitizeDicionary(properties) ?? [:]) { prop, _ in prop }
 
         let distinctId = getDistinctId()
+
+        let properties = buildProperties(distinctId: distinctId, properties: props)
+        let sanitizedProperties = sanitizeProperties(properties)
+
         queue.add(PostHogEvent(
             event: "$screen",
             distinctId: distinctId,
-            properties: buildProperties(distinctId: distinctId, properties: props)
+            properties: sanitizedProperties
         ))
     }
 
+    private func sanitizeProperties(_ properties: [String: Any]) -> [String: Any] {
+        if let sanitizer = config.propertiesSanitizer {
+            return sanitizer.sanitize(properties)
+        }
+        return properties
+    }
+
     @objc public func alias(_ alias: String) {
         if !isEnabled() {
             return
@@ -538,10 +556,14 @@ private let sessionChangeThreshold: TimeInterval = 60 * 30
         let props = ["alias": alias]
 
         let distinctId = getDistinctId()
+
+        let properties = buildProperties(distinctId: distinctId, properties: props)
+        let sanitizedProperties = sanitizeProperties(properties)
+
         queue.add(PostHogEvent(
             event: "$create_alias",
             distinctId: distinctId,
-            properties: buildProperties(distinctId: distinctId, properties: props)
+            properties: sanitizedProperties
         ))
     }
 
@@ -597,10 +619,14 @@ private let sessionChangeThreshold: TimeInterval = 60 * 30
 
         // Same as .group but without associating the current user with the group
         let distinctId = getDistinctId()
+
+        let properties = buildProperties(distinctId: distinctId, properties: props)
+        let sanitizedProperties = sanitizeProperties(properties)
+
         queue.add(PostHogEvent(
             event: "$groupidentify",
             distinctId: distinctId,
-            properties: buildProperties(distinctId: distinctId, properties: props)
+            properties: sanitizedProperties
         ))
     }
 

PostHogTests/ExampleSanitizer.swift

@@ -0,0 +1,23 @@
+//
+//  ExampleSanitizer.swift
+//  PostHogTests
+//
+//  Created by Manoel Aranda Neto on 06.08.24.
+//
+
+import Foundation
+import PostHog
+
+class ExampleSanitizer: PostHogPropertiesSanitizer {
+    public func sanitize(_ properties: [String: Any]) -> [String: Any] {
+        var sanitizedProperties = properties
+        // Perform sanitization
+        // For example, removing keys with empty values
+        for (key, value) in properties {
+            if let stringValue = value as? String, stringValue.isEmpty {
+                sanitizedProperties.removeValue(forKey: key)
+            }
+        }
+        return sanitizedProperties
+    }
+}

PostHogTests/PostHogSDKTest.swift

@@ -16,7 +16,8 @@ class PostHogSDKTest: QuickSpec {
                 sendFeatureFlagEvent: Bool = false,
                 captureApplicationLifecycleEvents: Bool = false,
                 flushAt: Int = 1,
-                optOut: Bool = false) -> PostHogSDK
+                optOut: Bool = false,
+                propertiesSanitizer: PostHogPropertiesSanitizer? = nil) -> PostHogSDK
     {
         let config = PostHogConfig(apiKey: "123", host: "http://localhost:9001")
         config.flushAt = flushAt
@@ -26,6 +27,7 @@ class PostHogSDKTest: QuickSpec {
         config.disableQueueTimerForTesting = true
         config.captureApplicationLifecycleEvents = captureApplicationLifecycleEvents
         config.optOut = optOut
+        config.propertiesSanitizer = propertiesSanitizer
         return PostHogSDK.with(config)
     }
 
@@ -704,6 +706,22 @@ class PostHogSDKTest: QuickSpec {
 
             expect(FileManager.default.fileExists(atPath: appFolder.path)) == true
         }
+
+        it("client sanitize properties") {
+            let sanitizer = ExampleSanitizer()
+            let sut = self.getSut(propertiesSanitizer: sanitizer)
+
+            let props: [String: Any] = ["empty": ""]
+
+            sut.capture("event", properties: props)
+
+            let events = getBatchedEvents(server)
+
+            expect(events[0].properties["empty"] as? String).to(beNil())
+
+            sut.reset()
+            sut.close()
+        }
     }
 }