Fix JSON string-array serialization in TgTypeParser

parseArray<std::string> call sites passed an identity lambda that
returned the raw string unchanged, producing `[a,b]` instead of
`["a","b"]`. The resulting invalid JSON broke sticker creation via
createNewStickerSet / addStickerToSet (emoji_list and keywords were
serialized as naked identifier lists) and Api::setWebhook
(allowed_updates missing element quotes).

Added a private appendStringArrayToJson helper that emits
`"name":["escaped","values"],` directly, escaping each element with
StringTools::escapeJsonString. Replaced the seven broken call sites
in TgTypeParser (WebhookInfo.allowed_updates, Chat.active_usernames,
Giveaway.country_codes, InputSticker.emoji_list, InputSticker.keywords,
and both PassportElementError file_hashes variants) and fixed the
one remaining lambda site in Api::setWebhook to match the pattern
already used by the other Api.cpp call sites.

Added three regression tests covering InputSticker serialization.

Closes #346

Author: Dramex

include/tgbot/TgTypeParser.h

@@ -957,6 +957,10 @@ class TGBOT_API TgTypeParser {
     }
 
     void appendToJson(std::string& json, const std::string& varName, const std::string& value) const;
+
+    /// Appends `"varName":["escapedValue1","escapedValue2",...],` to `json`.
+    /// Does nothing when `values` is empty. Each element is JSON-escaped.
+    void appendStringArrayToJson(std::string& json, const std::string& varName, const std::vector<std::string>& values) const;
 };
 }
 

src/Api.cpp

@@ -59,7 +59,7 @@ bool Api::setWebhook(const std::string& url,
     if (allowedUpdates != nullptr) {
         auto allowedUpdatesJson = _tgTypeParser.parseArray<std::string>(
             [] (const std::string& s)->std::string {
-            return s;
+            return "\"" + StringTools::escapeJsonString(s) + "\"";
         }, *allowedUpdates);
         args.emplace_back("allowed_updates", allowedUpdatesJson);
     }

src/TgTypeParser.cpp

@@ -1,5 +1,7 @@
 #include "tgbot/TgTypeParser.h"
 
+#include "tgbot/tools/StringTools.h"
+
 namespace TgBot {
 
 Update::Ptr TgTypeParser::parseJsonAndGetUpdate(const boost::property_tree::ptree& data) const {
@@ -97,10 +99,7 @@ std::string TgTypeParser::parseWebhookInfo(const WebhookInfo::Ptr& object) const
     appendToJson(result, "last_error_message", object->lastErrorMessage);
     appendToJson(result, "last_synchronization_error_date", object->lastSynchronizationErrorDate);
     appendToJson(result, "max_connections", object->maxConnections);
-    appendToJson(result, "allowed_updates", parseArray<std::string>(
-        [] (const std::string& s)->std::string {
-        return s;
-    }, object->allowedUpdates));
+    appendStringArrayToJson(result, "allowed_updates", object->allowedUpdates);
     removeLastComma(result);
     result += '}';
     return result;
@@ -227,10 +226,7 @@ std::string TgTypeParser::parseChat(const Chat::Ptr& object) const {
     appendToJson(result, "last_name", object->lastName);
     appendToJson(result, "is_forum", object->isForum);
     appendToJson(result, "photo", parseChatPhoto(object->photo));
-    appendToJson(result, "active_usernames", parseArray<std::string>(
-        [] (const std::string& s)->std::string {
-        return s;
-    }, object->activeUsernames));
+    appendStringArrayToJson(result, "active_usernames", object->activeUsernames);
     appendToJson(result, "birthdate", parseBirthdate(object->birthdate));
     appendToJson(result, "business_intro", parseBusinessIntro(object->businessIntro));
     appendToJson(result, "business_location", parseBusinessLocation(object->businessLocation));
@@ -1650,10 +1646,7 @@ std::string TgTypeParser::parseGiveaway(const Giveaway::Ptr& object) const {
     appendToJson(result, "only_new_members", object->onlyNewMembers);
     appendToJson(result, "has_public_winners", object->hasPublicWinners);
     appendToJson(result, "prize_description", object->prizeDescription);
-    appendToJson(result, "country_codes", parseArray<std::string>(
-        [] (const std::string& s)->std::string {
-        return s;
-    }, object->countryCodes));
+    appendStringArrayToJson(result, "country_codes", object->countryCodes);
     appendToJson(result, "premium_subscription_month_count", object->premiumSubscriptionMonthCount);
     removeLastComma(result);
     result += '}';
@@ -3819,15 +3812,9 @@ std::string TgTypeParser::parseInputSticker(const InputSticker::Ptr& object) con
     result += '{';
     appendToJson(result, "sticker", object->sticker);
     appendToJson(result, "format", object->format);
-    appendToJson(result, "emoji_list", parseArray<std::string>(
-        [] (const std::string& s)->std::string {
-        return s;
-    }, object->emojiList));
+    appendStringArrayToJson(result, "emoji_list", object->emojiList);
     appendToJson(result, "mask_position", parseMaskPosition(object->maskPosition));
-    appendToJson(result, "keywords", parseArray<std::string>(
-        [] (const std::string& s)->std::string {
-        return s;
-    }, object->keywords));
+    appendStringArrayToJson(result, "keywords", object->keywords);
     removeLastComma(result);
     result += '}';
     return result;
@@ -5416,10 +5403,7 @@ std::string TgTypeParser::parsePassportElementErrorFiles(const PassportElementEr
     // This function will be called by parsePassportElementError(), so I don't add
     // curly brackets to the result std::string.
     std::string result;
-    appendToJson(result, "file_hashes",
-                 parseArray<std::string>([] (const std::string& s)->std::string {
-        return s;
-    }, object->fileHashes));
+    appendStringArrayToJson(result, "file_hashes", object->fileHashes);
     // The last comma will be erased by parsePassportElementError().
     return result;
 }
@@ -5460,10 +5444,7 @@ std::string TgTypeParser::parsePassportElementErrorTranslationFiles(const Passpo
     // This function will be called by parsePassportElementError(), so I don't add
     // curly brackets to the result std::string.
     std::string result;
-    appendToJson(result, "file_hashes",
-                 parseArray<std::string>([] (const std::string& s)->std::string {
-        return s;
-    }, object->fileHashes));
+    appendStringArrayToJson(result, "file_hashes", object->fileHashes);
     // The last comma will be erased by parsePassportElementError().
     return result;
 }
@@ -5582,6 +5563,24 @@ std::string TgTypeParser::parseGenericReply(const GenericReply::Ptr& object) con
     return "";
 }
 
+void TgTypeParser::appendStringArrayToJson(std::string& json, const std::string& varName, const std::vector<std::string>& values) const {
+    if (values.empty()) {
+        return;
+    }
+    json += '"';
+    json += varName;
+    json += R"(":[)";
+    for (std::size_t i = 0; i < values.size(); ++i) {
+        if (i != 0) {
+            json += ',';
+        }
+        json += '"';
+        json += StringTools::escapeJsonString(values[i]);
+        json += '"';
+    }
+    json += "],";
+}
+
 void TgTypeParser::appendToJson(std::string& json, const std::string& varName, const std::string& value) const {
     if (value.empty()) {
         return;

test/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(TEST_SRC_LIST
     main.cpp
     tgbot/Api.cpp
+    tgbot/TgTypeParser.cpp
     tgbot/net/Url.cpp
     tgbot/net/HttpParser.cpp
     tgbot/tools/StringTools.cpp

test/tgbot/TgTypeParser.cpp

@@ -0,0 +1,61 @@
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <boost/test/unit_test.hpp>
+
+#include "tgbot/TgTypeParser.h"
+#include "tgbot/types/InputSticker.h"
+
+using namespace std;
+using namespace TgBot;
+
+BOOST_AUTO_TEST_SUITE(tTgTypeParser)
+
+// Regression tests for https://github.com/reo7sp/tgbot-cpp/issues/346 —
+// string arrays were emitted as `[a,b]` (unquoted identifiers) instead of
+// `["a","b"]`, producing invalid JSON and breaking sticker creation.
+
+BOOST_AUTO_TEST_CASE(parseInputStickerEmojiListIsJsonArray) {
+    TgTypeParser parser;
+    auto sticker = make_shared<InputSticker>();
+    sticker->sticker = "file_id_abc";
+    sticker->format = "static";
+    sticker->emojiList = {"smile", "heart"};
+
+    const string json = parser.parseInputSticker(sticker);
+
+    BOOST_CHECK(json.find(R"("emoji_list":["smile","heart"])") != string::npos);
+    // The pre-fix output emitted the array as `[smile,heart]` — assert no regression.
+    BOOST_CHECK(json.find("[smile,heart]") == string::npos);
+}
+
+BOOST_AUTO_TEST_CASE(parseInputStickerEscapesJsonSpecialsInEmoji) {
+    TgTypeParser parser;
+    auto sticker = make_shared<InputSticker>();
+    sticker->sticker = "id";
+    sticker->format = "static";
+    sticker->emojiList = {R"(a"b)", R"(c\d)"};
+
+    const string json = parser.parseInputSticker(sticker);
+
+    BOOST_CHECK(json.find(R"("a\"b")") != string::npos);
+    BOOST_CHECK(json.find(R"("c\\d")") != string::npos);
+}
+
+BOOST_AUTO_TEST_CASE(parseInputStickerOmitsEmptyKeywords) {
+    // Empty arrays should not appear in the output at all, matching the
+    // behaviour of the previous `appendToJson(... parseArray(...))` pattern.
+    TgTypeParser parser;
+    auto sticker = make_shared<InputSticker>();
+    sticker->sticker = "id";
+    sticker->format = "static";
+    sticker->emojiList = {"a"};
+    // keywords is default-constructed empty
+
+    const string json = parser.parseInputSticker(sticker);
+
+    BOOST_CHECK(json.find("keywords") == string::npos);
+}
+
+BOOST_AUTO_TEST_SUITE_END()