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I'm using Qt and trying to take the following and convert it into JSON text, but when I attempt to compile it I get a symbols not found for architecture error.

I'm currently using the builtin Qt Json library as I do not know how to get QJson to work and compile statically into the code so that there are no dependencies.

// Create the message body QVariantMap message; message.insert("date", QDate::currentDate().toString()); message.insert("eventType", eventName); message.insert("payload", messagePayload); // Initialize the Serializer QJson::Serializer serializer; bool ok; // Serialize the data QByteArray json = serializer.serialize(message, &ok);

The compiler output is the following:

Undefined symbols for architecture x86_64: "QJson::Serializer::serialize(QVariant const&, bool*)", referenced from: SWebsocketClient::sendMessage(QString, QMap<QString, QVariant>) in swebsocketclient.o

Is this kindof the right way to do this, or is there a much better? I know this question has been asked elsewhere, however most of the articles linked to in other answers do not exist anymore.

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  • Offhand it looks like the QJson library isn't built for that architecture. Commented Jan 21, 2013 at 20:51
  • How did you obtain/build Qjson? How do you link it? Show your .pro file. Commented Jan 21, 2013 at 21:31
  • @FrankOsterfeld I did nothing to build/obtain QJson. I tried installing it via homebrew on my mac and then adding "QT += sql qjson" to my .pro file, but I thought Qt had some JSON support builtin? If not, how is it that I use QJson in my project if I install it view homebrew? Commented Jan 22, 2013 at 0:25
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    If it was built-in, one wouldn't need qjson (Json support is part of Qt5, not part of Qt4 though). For CONFIG += qjson (CONFIG, not QT) to work, qjson would need to install a .prf file, which I don't see in the repo. (It's using CMake which makes these things a lot easier). So I assume you need to do LIBS += -lqjson manually Commented Jan 22, 2013 at 7:41
  • @FrankOsterfeld That worked! Thanks! I don't know if you want to post that as an answer or if I should go ahead and answer my own question. But I think you should take the credit. Commented Jan 22, 2013 at 18:21

1 Answer 1

Reset to default
2

You can always use this JSON library instead:

/* * qvjson.h * * Created on: Apr 23, 2010 * Author: drh */ #ifndef QVJSON_H_ #define QVJSON_H_ #include <QMap> #include <QList> #include <QVariant> #include <QRegExp> class QvJson { public: QvJson(); virtual ~QvJson(); QVariant parseJson(const QString& jsonString); // The jsonObject is a QVariant that may be a -- // -- QMap<QString, QVariant> // -- QList<QVariant> // -- QString // -- integer // -- real number // -- bool // -- null (implemented as a QVariant() object) // Where QVariant appears in the above list, it may recursively // be one of the above. QString encodeJson(const QVariant& jsonObject); private: enum Error { ErrorUnrecognizedToken, ErrorMustBeString, ErrorMissingColon, ErrorMissingCommaOrClose, ErrorNoClosingQuote, ErrorEndOfInput, ErrorInvalidNumericValue, ErrorInvalidHexValue, ErrorUnrecognizedObject }; QRegExp mNonBlank; QRegExp mFindQuote; QString nextToken(const QString& jsonString, int& position); QString peekToken(const QString& jsonString, int position); QVariant parseInternal(const QString& jsonString, int& position, int nesting); QVariant parseObject(const QString& jsonString, int& position, int nesting); QVariant parseArray(const QString& jsonString, int& position, int nesting); QVariant parseString(const QString& jsonString, int& position, int nesting); QVariant parseBool(const QString& jsonString, int& position, int nesting); QVariant parseNull(const QString& jsonString, int& position, int nesting); QVariant parseNumber(const QString& jsonString, int& position, int nesting); QVariant syntaxError(const QString& method, const QString& jsonString, int position, int nesting, Error error); QString encodeObject(const QVariant& jsonObject); QString encodeArray(const QVariant& jsonObject); QString encodeString(const QVariant& jsonObject); QString encodeString(const QString& value); QString encodeNumeric(const QVariant& jsonObject); QString encodeBool(const QVariant& jsonObject); QString encodeNull(const QVariant& jsonObject); QString encodingError(const QString& method, const QVariant& jsonObject, Error error); }; #endif /* QVJSON_H_ */ /* * qvjson.cpp * * Created on: Apr 23, 2010 * Author: drh */ #include "qvjson.h" #include <QStringList> #include <QMessageBox> QvJson::QvJson() { mNonBlank = QRegExp("\\S", Qt::CaseSensitive, QRegExp::RegExp); mFindQuote = QRegExp("[^\\\\]\"", Qt::CaseSensitive, QRegExp::RegExp); } QvJson::~QvJson() { // TODO Auto-generated destructor stub } QVariant QvJson::parseJson(const QString& jsonString) { int position = 0; QVariant result; result = parseInternal(jsonString, position, 0); if (result.type() == QVariant::StringList) { QMessageBox::critical(NULL, "", result.toString()); } QString token(nextToken(jsonString, position)); if (!token.isEmpty()) { QMessageBox::critical(NULL, "", QObject::tr("Invalid JSON string -- remaining token %1 at position %2.").arg(token).arg(position)); } return result; } QString QvJson::nextToken(const QString& jsonString, int& position) { if (position >= jsonString.count()) { return QString(); } while (jsonString.at(position) == ' ') { position++; if (position >= jsonString.count()) { return QString(); } } if (jsonString.at(position).isLetter()) { if (position + 4 < jsonString.count()) { QString word = jsonString.mid(position, 4); if ((word == "true") || (word == "null")) { position += 4; while (position < jsonString.count() && jsonString.at(position) == ' ') { position++; } return word; } if ((word == "fals") && (position + 5 < jsonString.count()) && jsonString.at(position + 4) == 'e') { position += 5; while (position < jsonString.count() && jsonString.at(position) == ' ') { position++; } return "false"; } } } QString result = QString(jsonString.at(position)); position++; while (position < jsonString.count() && jsonString.at(position) == ' ') { position++; } return result; } // By virtue of its non-& position parm, this method "peeks" at the token without consuming it. QString QvJson::peekToken(const QString& jsonString, int position) { return (nextToken(jsonString, position)); } QVariant QvJson::parseInternal(const QString& jsonString, int& position, int nesting) { QString token(peekToken(jsonString, position)); QVariant result; int startPosition = position; // For debug Q_UNUSED(startPosition); if (token.isNull()) { result = syntaxError("parseInternal", jsonString, position, nesting + 1, ErrorEndOfInput); } else if (token == "{") { result = parseObject(jsonString, position, nesting + 1); } else if (token == "[") { result = parseArray(jsonString, position, nesting + 1); } else if (token == "\"") { result = parseString(jsonString, position, nesting + 1); } else if ((token == "true") || (token == "false")) { result = parseBool(jsonString, position, nesting + 1); } else if (token == "null") { result = parseNull(jsonString, position, nesting + 1); } else if ((token == "-") || (token.at(0).isDigit())) { result = parseNumber(jsonString, position, nesting + 1); } else { result = syntaxError("parseInternal", jsonString, position, nesting + 1, ErrorUnrecognizedToken); } return result; } QVariant QvJson::parseObject(const QString& jsonString, int& position, int nesting) { QMap<QString, QVariant> resultObject; QString token; int startPosition = position; // For debug Q_UNUSED(startPosition); token = nextToken(jsonString, position); Q_ASSERT(token == "{"); // Handle case of empty object token = peekToken(jsonString, position); if (token == '}') { return QVariant(resultObject); } do { // Next item must be a string token = peekToken(jsonString, position); if (token != "\"") { return syntaxError("parseObject", jsonString, position, nesting + 1, ErrorMustBeString); } QVariant propName; propName = parseString(jsonString, position, nesting + 1); // Check for error if (propName.type() == QVariant::StringList) { QStringList propNameError(propName.toStringList()); propNameError << QObject::tr("in parseObject(%1,%2)").arg(position).arg(nesting); return QVariant(propNameError); } // Expect a ":" token = nextToken(jsonString, position); if (token != ":") { return syntaxError("parseObject", jsonString, position, nesting + 1, ErrorMissingColon); } // Now get the value QVariant propValue; propValue = parseInternal(jsonString, position, nesting + 1); // Check for error if (propValue.type() == QVariant::StringList) { QStringList propValueError(propValue.toStringList()); propValueError << QObject::tr("in parseObject(%1,%2)").arg(position).arg(nesting); return QVariant(propValueError); } resultObject[propName.toString()] = propValue; // Next token must be a "," or "}" token = nextToken(jsonString, position); if (token == "}") { return QVariant(resultObject); } else if (token != ",") { return syntaxError("parseObject", jsonString, position, nesting + 1, ErrorMissingCommaOrClose); } } while (true); } QVariant QvJson::parseArray(const QString& jsonString, int& position, int nesting) { QList<QVariant> resultArray; QString token; token = nextToken(jsonString, position); Q_ASSERT(token == "["); // Handle case of empty object token = peekToken(jsonString, position); if (token == ']') { return QVariant(resultArray); } do { // Get the element of the array QVariant propValue; propValue = parseInternal(jsonString, position, nesting + 1); // Check for error if (propValue.type() == QVariant::StringList) { QStringList propValueError(propValue.toStringList()); propValueError << QObject::tr("in parseObject(%1,%2)").arg(position).arg(nesting); return QVariant(propValueError); } resultArray << propValue; // Next token must be a "," or "]" token = nextToken(jsonString, position); if (token == "]") { return QVariant(resultArray); } else if (token != ",") { return syntaxError("parseArray", jsonString, position, nesting + 1, ErrorMissingCommaOrClose); } } while (true); } QVariant QvJson::parseString(const QString& jsonString, int& position, int nesting) { QString result; // Skip over the double quote character Q_ASSERT(jsonString.at(position) == '"'); position++; do { if (position >= jsonString.count()) { return syntaxError("parseString", jsonString, position, nesting, ErrorNoClosingQuote); } if (jsonString.at(position) == '"') { break; } if (jsonString.at(position) == '\\') { position++; if (position >= jsonString.count()) { return syntaxError("parseString", jsonString, position, nesting, ErrorNoClosingQuote); } switch (jsonString.at(position).unicode()) { case 'b': result.append('\b'); break; case 'f': result.append('\f'); break; case 'n': result.append('\n'); break; case 'r': result.append('\r'); break; case 't': result.append('\t'); break; case 'u': { if (position + 4 >= jsonString.count()) { return syntaxError("parseString", jsonString, position, nesting, ErrorNoClosingQuote); } QString hex = jsonString.mid(position + 1, 4); bool ok; int value = hex.toInt(&ok, 16); if (!ok) { return syntaxError("parseString", jsonString, position+1, nesting, ErrorInvalidHexValue); } result.append(QChar(value)); position += 4; } default: result.append(jsonString.at(position)); } position++; } else { result.append(jsonString.at(position)); position++; } } while(true); Q_ASSERT(jsonString.at(position) == '"'); position++; return QVariant(result); } QVariant QvJson::parseBool(const QString& jsonString, int& position, int nesting) { bool resultBool; QString token; token = nextToken(jsonString, position); if (token == "true") { resultBool = true; } else if (token == "false") { resultBool = false; } else { Q_ASSERT(false); } return QVariant(resultBool); } QVariant QvJson::parseNull(const QString& jsonString, int& position, int nesting) { QString token; token = nextToken(jsonString, position); Q_ASSERT(token == "null"); Q_UNUSED(token); return QVariant(); } QVariant QvJson::parseNumber(const QString& jsonString, int& position, int nesting) { int startPosition = position; // Allow a leading minus sign if (jsonString.at(position) == '-') position++; if (position >= jsonString.count()) { return syntaxError("parseNumber", jsonString, position, nesting + 1, ErrorEndOfInput); } // Allow one or more decimal digits if (!jsonString.at(position).isDigit()) { return syntaxError("parseNumber", jsonString, position, nesting + 1, ErrorInvalidNumericValue); } while (position < jsonString.count() && jsonString.at(position).isDigit()) { position++; } if (position >= jsonString.count() || (jsonString.at(position) != '.' && jsonString.at(position) != 'e' && jsonString.at(position) != 'E')) { bool ok = false; int resultInt = jsonString.mid(startPosition, position - startPosition).toInt(&ok); if (!ok) { return syntaxError("parseNumber", jsonString, position, nesting + 1, ErrorInvalidNumericValue); } return QVariant(resultInt); } // Consume any fraction part if (jsonString.at(position) == '.') { position++; while (position < jsonString.count() && jsonString.at(position).isDigit()) { position++; } } // Consume any exponent part if (jsonString.at(position) == 'e' || jsonString.at(position) == 'E') { position++; // Consume +/- if present if (jsonString.at(position) == '+' || jsonString.at(position) == '-') { position++; } // Must have at least one digit if (!jsonString.at(position).isDigit()) { return syntaxError("parseNumber", jsonString, position, nesting + 1, ErrorInvalidNumericValue); } while (position < jsonString.count() && jsonString.at(position).isDigit()) { position++; } } // Should have a valid floating point value at this point bool ok = false; qreal resultReal = jsonString.mid(startPosition, position - startPosition).toDouble(&ok); if (!ok) { return syntaxError("parseNumber", jsonString, position, nesting + 1, ErrorInvalidNumericValue); } return QVariant(resultReal); } QVariant QvJson::syntaxError(const QString& method, const QString& jsonString, int position, int nesting, Error error) { QString text; switch (error) { case ErrorInvalidNumericValue: text = QObject::tr("Invalid numeric value"); break; case ErrorInvalidHexValue: text = QObject::tr("Invalid hex value"); break; case ErrorEndOfInput: text = QObject::tr("Unexpected end of input"); break; case ErrorNoClosingQuote: text = QObject::tr("No closing quote for literal string"); break; case ErrorMissingColon: text = QObject::tr("Missing ':' between attribute name and value"); break; case ErrorMissingCommaOrClose: text = QObject::tr("Missing comma, '}', or ']'"); break; case ErrorMustBeString: text = QObject::tr("The name of an attribute must be a valid character string"); break; case ErrorUnrecognizedToken: text = QObject::tr("The token was not recognized"); break; default: Q_ASSERT(false); } QString errorMsg = QObject::tr("*** Error %1 in QvJson::%2 at position %3 -- %4").arg(error).arg(method).arg(position).arg(text); QStringList errorList; errorList << errorMsg; return QVariant(errorList); } QString QvJson::encodeJson(const QVariant& jsonObject) { QVariant::Type type = jsonObject.type(); switch (type) { case QVariant::Map: return encodeObject(jsonObject); case QVariant::List: return encodeArray(jsonObject); case QVariant::String: return encodeString(jsonObject); case QVariant::Int: case QVariant::Double: return encodeNumeric(jsonObject); case QVariant::Bool: return encodeBool(jsonObject); case QVariant::Invalid: return encodeNull(jsonObject); default: return encodingError("encodeJson", jsonObject, ErrorUnrecognizedObject); } } QString QvJson::encodeObject(const QVariant& jsonObject) { QString result("{ "); QMap<QString, QVariant> map = jsonObject.toMap(); QMapIterator<QString, QVariant> i(map); while (i.hasNext()) { i.next(); result.append(encodeString(i.key())); result.append(" : "); result.append(encodeJson(i.value())); if (i.hasNext()) { result.append(", "); } } result.append(" }"); return result; } QString QvJson::encodeArray(const QVariant& jsonObject) { QString result("[ "); QList<QVariant> list = jsonObject.toList(); for (int i = 0; i < list.count(); i++) { result.append(encodeJson(list.at(i))); if (i+1 < list.count()) { result.append(", "); } } result.append(" ]"); return result; } QString QvJson::encodeString(const QVariant &jsonObject) { return encodeString(jsonObject.toString()); } QString QvJson::encodeString(const QString& value) { QString result = "\""; for (int i = 0; i < value.count(); i++) { ushort chr = value.at(i).unicode(); if (chr < 32) { switch (chr) { case '\b': result.append("\\b"); break; case '\f': result.append("\\f"); break; case '\n': result.append("\\n"); break; case '\r': result.append("\\r"); break; case '\t': result.append("\\t"); break; default: result.append("\\u"); result.append(QString::number(chr, 16).rightJustified(4, '0')); } // End switch } else if (chr > 255) { result.append("\\u"); result.append(QString::number(chr, 16).rightJustified(4, '0')); } else { result.append(value.at(i)); } } result.append('"'); QString displayResult = result; // For debug, since "result" often doesn't show Q_UNUSED(displayResult); return result; } QString QvJson::encodeNumeric(const QVariant& jsonObject) { return jsonObject.toString(); } QString QvJson::encodeBool(const QVariant& jsonObject) { return jsonObject.toString(); } QString QvJson::encodeNull(const QVariant& jsonObject) { return "null"; } QString QvJson::encodingError(const QString& method, const QVariant& jsonObject, Error error) { QString text; switch (error) { case ErrorUnrecognizedObject: text = QObject::tr("Unrecognized object type"); break; default: Q_ASSERT(false); } return QObject::tr("*** Error %1 in QvJson::%2 -- %3").arg(error).arg(method).arg(text); }
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2 Comments

Not sure copy/pasting yet another Qt json implementation (without included unit tests) from the web will improve the maintainability.
@FrankOsterfeld - Not from the web. From my private stash.

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