api: Add ZulipStream.topicsPolicy

lib/api/model/events.dart

@@ -681,6 +681,8 @@ class ChannelUpdateEvent extends ChannelEvent {
         return value as bool;
       case ChannelPropertyName.messageRetentionDays:
         return value as int?;
+      case ChannelPropertyName.topicsPolicy:
+        return TopicsPolicy.fromApiValue(value as String);
       case ChannelPropertyName.channelPostPolicy:
         return ChannelPostPolicy.fromApiValue(value as int);
       case ChannelPropertyName.folderId:

lib/api/model/initial_snapshot.dart

@@ -90,6 +90,8 @@ class InitialSnapshot {
   /// Search for "realm_wildcard_mention_policy" in https://zulip.com/api/register-queue.
   final RealmWildcardMentionPolicy realmWildcardMentionPolicy;
 
+  final RealmTopicsPolicy realmTopicsPolicy;
+
   final bool realmMandatoryTopics;
 
   final String realmName;
@@ -183,6 +185,7 @@ class InitialSnapshot {
     required this.realmCanDeleteOwnMessageGroup,
     required this.realmDeleteOwnMessagePolicy,
     required this.realmWildcardMentionPolicy,
+    required this.realmTopicsPolicy,
     required this.realmMandatoryTopics,
     required this.realmName,
     required this.realmWaitingPeriodThreshold,
@@ -207,6 +210,22 @@ class InitialSnapshot {
   Map<String, dynamic> toJson() => _$InitialSnapshotToJson(this);
 }
 
+/// A value of [InitialSnapshot.realmTopicsPolicy].
+///
+/// For docs, search for "realm_topics_policy"
+/// in <https://zulip.com/api/register-queue#response>.
+@JsonEnum(fieldRename: FieldRename.snake)
+enum RealmTopicsPolicy {
+  allowEmptyTopic,
+  disableEmptyTopic;
+
+  static RealmTopicsPolicy fromApiValue(String apiValue)=> _byApiValue[apiValue] ?? allowEmptyTopic;
+
+  static final _byApiValue = _$RealmTopicsPolicyEnumMap.map((key, value) => MapEntry(value, key));
+
+  String toJson() => _$RealmTopicsPolicyEnumMap[this]!;
+}
+
 @JsonEnum(valueField: 'apiValue')
 enum RealmWildcardMentionPolicy {
   everyone(apiValue: 1),

lib/api/model/model.dart

@@ -659,6 +659,8 @@ class ZulipStream {
   bool isWebPublic; // present since 2.1, according to /api/changelog
   bool historyPublicToSubscribers;
   int? messageRetentionDays;
+  @JsonKey(defaultValue: TopicsPolicy.inherit) // TODO(server-11) remove default value
+  TopicsPolicy topicsPolicy;
   @JsonKey(name: 'stream_post_policy')
   ChannelPostPolicy? channelPostPolicy; // TODO(server-10) remove
   // final bool isAnnouncementOnly; // deprecated for `channelPostPolicy`; ignore
@@ -684,6 +686,7 @@ class ZulipStream {
     required this.isWebPublic,
     required this.historyPublicToSubscribers,
     required this.messageRetentionDays,
+    required this.topicsPolicy,
     required this.channelPostPolicy,
     required this.folderId,
     required this.canAddSubscribersGroup,
@@ -708,6 +711,7 @@ class ZulipStream {
       isWebPublic: subscription.isWebPublic,
       historyPublicToSubscribers: subscription.historyPublicToSubscribers,
       messageRetentionDays: subscription.messageRetentionDays,
+      topicsPolicy: subscription.topicsPolicy,
       channelPostPolicy: subscription.channelPostPolicy,
       folderId: subscription.folderId,
       canAddSubscribersGroup: subscription.canAddSubscribersGroup,
@@ -744,6 +748,7 @@ enum ChannelPropertyName {
   // isWebPublic is updated via its own [ChannelUpdateEvent] field
   // historyPublicToSubscribers is updated via its own [ChannelUpdateEvent] field
   messageRetentionDays,
+  topicsPolicy,
   @JsonValue('stream_post_policy')
   channelPostPolicy,
   folderId,
@@ -765,6 +770,24 @@ enum ChannelPropertyName {
     .map((key, value) => MapEntry(value, key));
 }
 
+/// A value of [ZulipStream.topicsPolicy].
+///
+/// For docs, search for "topics_policy"
+/// in <https://zulip.com/api/get-stream-by-id>.
+@JsonEnum(fieldRename: FieldRename.snake)
+enum TopicsPolicy {
+  inherit,
+  allowEmptyTopic,
+  disableEmptyTopic,
+  emptyTopicOnly;
+
+  static TopicsPolicy fromApiValue(String apiValue) => _byApiValue[apiValue] ?? inherit;
+
+  static final _byApiValue = _$TopicsPolicyEnumMap.map((key, value) => MapEntry(value, key));
+
+  String toJson() => _$TopicsPolicyEnumMap[this]!;
+}
+
 /// Policy for which users can post to the stream.
 ///
 /// For docs, search for "stream_post_policy"
@@ -830,6 +853,7 @@ class Subscription extends ZulipStream {
     required super.isWebPublic,
     required super.historyPublicToSubscribers,
     required super.messageRetentionDays,
+    required super.topicsPolicy,
     required super.channelPostPolicy,
     required super.folderId,
     required super.canAddSubscribersGroup,

lib/model/channel.dart

@@ -444,6 +444,8 @@ class ChannelStoreImpl extends HasUserStore with ChannelStore {
             stream.inviteOnly = event.value as bool;
           case ChannelPropertyName.messageRetentionDays:
             stream.messageRetentionDays = event.value as int?;
+          case ChannelPropertyName.topicsPolicy:
+            stream.topicsPolicy = event.value as TopicsPolicy;
           case ChannelPropertyName.channelPostPolicy:
             stream.channelPostPolicy = event.value as ChannelPostPolicy;
           case ChannelPropertyName.folderId:

lib/model/realm.dart

@@ -46,6 +46,7 @@ mixin RealmStore on PerAccountStoreBase, UserGroupStore {
   GroupSettingValue? get realmCanDeleteAnyMessageGroup; // TODO(server-10)
   GroupSettingValue? get realmCanDeleteOwnMessageGroup; // TODO(server-10)
   bool get realmEnableReadReceipts;
+  RealmTopicsPolicy get realmTopicsPolicy;
   bool get realmMandatoryTopics;
   int get maxFileUploadSizeMib;
   int? get realmMessageContentDeleteLimitSeconds;
@@ -174,6 +175,8 @@ mixin ProxyRealmStore on RealmStore {
   @override
   bool get realmEnableReadReceipts => realmStore.realmEnableReadReceipts;
   @override
+  RealmTopicsPolicy get realmTopicsPolicy => realmStore.realmTopicsPolicy;
+  @override
   bool get realmMandatoryTopics => realmStore.realmMandatoryTopics;
   @override
   int get maxFileUploadSizeMib => realmStore.maxFileUploadSizeMib;
@@ -233,6 +236,7 @@ class RealmStoreImpl extends HasUserGroupStore with RealmStore {
     realmAllowMessageEditing = initialSnapshot.realmAllowMessageEditing,
     realmCanDeleteAnyMessageGroup = initialSnapshot.realmCanDeleteAnyMessageGroup,
     realmCanDeleteOwnMessageGroup = initialSnapshot.realmCanDeleteOwnMessageGroup,
+    realmTopicsPolicy = initialSnapshot.realmTopicsPolicy,
     realmMandatoryTopics = initialSnapshot.realmMandatoryTopics,
     maxFileUploadSizeMib = initialSnapshot.maxFileUploadSizeMib,
     realmMessageContentDeleteLimitSeconds = initialSnapshot.realmMessageContentDeleteLimitSeconds,
@@ -383,6 +387,8 @@ class RealmStoreImpl extends HasUserGroupStore with RealmStore {
   @override
   final bool realmEnableReadReceipts;
   @override
+  final RealmTopicsPolicy realmTopicsPolicy;
+  @override
   final bool realmMandatoryTopics;
   @override
   final int maxFileUploadSizeMib;

test/example_data.dart

@@ -464,6 +464,7 @@ ZulipStream stream({
   bool? isWebPublic,
   bool? historyPublicToSubscribers,
   int? messageRetentionDays,
+  TopicsPolicy? topicsPolicy,
   ChannelPostPolicy? channelPostPolicy,
   int? folderId,
   GroupSettingValue? canAddSubscribersGroup,
@@ -496,6 +497,7 @@ ZulipStream stream({
     isWebPublic: isWebPublic ?? false,
     historyPublicToSubscribers: historyPublicToSubscribers ?? true,
     messageRetentionDays: messageRetentionDays,
+    topicsPolicy: topicsPolicy ?? TopicsPolicy.inherit,
     channelPostPolicy: channelPostPolicy ?? ChannelPostPolicy.any,
     folderId: folderId,
     canAddSubscribersGroup: canAddSubscribersGroup ?? GroupSettingValueNamed(nobodyGroup.id),
@@ -541,6 +543,7 @@ Subscription subscription(
     isWebPublic: stream.isWebPublic,
     historyPublicToSubscribers: stream.historyPublicToSubscribers,
     messageRetentionDays: stream.messageRetentionDays,
+    topicsPolicy: stream.topicsPolicy,
     channelPostPolicy: stream.channelPostPolicy,
     folderId: stream.folderId,
     canAddSubscribersGroup: stream.canAddSubscribersGroup,
@@ -1261,6 +1264,8 @@ ChannelUpdateEvent channelUpdateEvent(
       assert(value is bool);
     case ChannelPropertyName.messageRetentionDays:
       assert(value is int?);
+    case ChannelPropertyName.topicsPolicy:
+      assert(value is TopicsPolicy);
     case ChannelPropertyName.channelPostPolicy:
       assert(value is ChannelPostPolicy);
     case ChannelPropertyName.folderId:
@@ -1335,6 +1340,7 @@ InitialSnapshot initialSnapshot({
   GroupSettingValue? realmCanDeleteOwnMessageGroup,
   RealmDeleteOwnMessagePolicy? realmDeleteOwnMessagePolicy,
   RealmWildcardMentionPolicy? realmWildcardMentionPolicy,
+  RealmTopicsPolicy? realmTopicsPolicy,
   bool? realmMandatoryTopics,
   String? realmName,
   int? realmWaitingPeriodThreshold,
@@ -1399,6 +1405,7 @@ InitialSnapshot initialSnapshot({
     realmCanDeleteOwnMessageGroup: realmCanDeleteOwnMessageGroup,
     realmDeleteOwnMessagePolicy: realmDeleteOwnMessagePolicy,
     realmWildcardMentionPolicy: realmWildcardMentionPolicy ?? RealmWildcardMentionPolicy.everyone,
+    realmTopicsPolicy: realmTopicsPolicy ?? RealmTopicsPolicy.allowEmptyTopic,
     realmMandatoryTopics: realmMandatoryTopics ?? true,
     realmName: realmName ?? 'Example Zulip organization',
     realmWaitingPeriodThreshold: realmWaitingPeriodThreshold ?? 0,