Deprecate QJsonDocument methods for converting to/from JSON binary

Also remove the example code for deprecated methods and use CBOR instead
where it makes sense.

Task-number: QTBUG-81068
Change-Id: Iffb7a4b3d7b16a1e485fc05b3ab2e2468e9e0718
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

examples/corelib/serialization/convert/jsonconverter.cpp

@@ -57,7 +57,6 @@
 #include <QJsonValue>
 
 static JsonConverter jsonConverter;
-static BinaryJsonConverter BinaryJsonConverter;
 
 static const char optionHelp[] =
         "compact=no|yes              Use compact JSON form.\n";
@@ -151,62 +150,3 @@ void JsonConverter::saveFile(QIODevice *f, const QVariant &contents, const QStri
 
     f->write(convertFromVariant(contents).toJson(format));
 }
-
-QString BinaryJsonConverter::name()
-{
-    return "binary-json";
-}
-
-Converter::Direction BinaryJsonConverter::directions()
-{
-    return InOut;
-}
-
-Converter::Options BinaryJsonConverter::outputOptions()
-{
-    return {};
-}
-
-const char *BinaryJsonConverter::optionsHelp()
-{
-    return nullptr;
-}
-
-bool BinaryJsonConverter::probeFile(QIODevice *f)
-{
-    return f->isReadable() && f->peek(4) == "qbjs";
-}
-
-QVariant BinaryJsonConverter::loadFile(QIODevice *f, Converter *&outputConverter)
-{
-    if (!outputConverter)
-        outputConverter = &jsonConverter;
-
-    QJsonDocument doc;
-    if (auto file = qobject_cast<QFile *>(f)) {
-        uchar *ptr = file->map(0, file->size());
-        if (ptr)
-            doc = QJsonDocument::fromRawData(reinterpret_cast<char *>(ptr), file->size());
-    }
-
-    if (doc.isNull())
-        doc = QJsonDocument::fromBinaryData(f->readAll());
-
-    if (!doc.isObject() && !doc.isArray()) {
-        fprintf(stderr, "Failed to load Binary JSON.\n");
-        exit(EXIT_FAILURE);
-    }
-    if (outputConverter == null)
-        return QVariant();
-    return doc.toVariant();
-}
-
-void BinaryJsonConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
-{
-    if (!options.isEmpty()) {
-        fprintf(stderr, "Unknown option '%s' to JSON output. This format has no options.\n", qPrintable(options.first()));
-        exit(EXIT_FAILURE);
-    }
-
-    f->write(convertFromVariant(contents).toBinaryData());
-}

examples/corelib/serialization/convert/jsonconverter.h

@@ -69,17 +69,4 @@ public:
     void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
 };
 
-class BinaryJsonConverter : public Converter
-{
-    // Converter interface
-public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
-};
-
 #endif // JSONCONVERTER_H

examples/corelib/serialization/savegame/doc/src/savegame.qdoc

@@ -37,8 +37,8 @@
     game generally involves serializing each game object's member variables
     to a file. Many formats can be used for this purpose, one of which is JSON.
     With QJsonDocument, you also have the ability to serialize a document in a
-    binary format, which is great if you don't want the save file to be
+    \l {https://tools.ietf.org/html/rfc7049} {CBOR} format, which is great if you
-    readable, or if you need to keep the file size down.
+    don't want the save file to be readable, or if you need to keep the file size down.
 
     In this example, we'll demonstrate how to save and load a simple game to
     and from JSON and binary formats.
@@ -133,7 +133,7 @@
 
     When loading a saved game in loadGame(), the first thing we do is open the
     save file based on which format it was saved to; \c "save.json" for JSON,
-    and \c "save.dat" for binary. We print a warning and return \c false if the
+    and \c "save.dat" for CBOR. We print a warning and return \c false if the
     file couldn't be opened.
 
     Since QJsonDocument's \l{QJsonDocument::fromJson()}{fromJson()} and
@@ -172,7 +172,7 @@
     \snippet serialization/savegame/main.cpp 1
 
     When the player has finished, we save their game. For demonstration
-    purposes, we can serialize to either JSON or binary. You can examine the
+    purposes, we can serialize to either JSON or CBOR. You can examine the
     contents of the files in the same directory as the executable (or re-run
     the example, making sure to also specify the "load" option), although the
     binary save file will contain some garbage characters (which is normal).

examples/corelib/serialization/savegame/game.cpp

@@ -50,6 +50,8 @@
 
 #include "game.h"
 
+#include <QCborMap>
+#include <QCborValue>
 #include <QFile>
 #include <QJsonArray>
 #include <QJsonDocument>
@@ -122,14 +124,14 @@ bool Game::loadGame(Game::SaveFormat saveFormat)
 
     QJsonDocument loadDoc(saveFormat == Json
         ? QJsonDocument::fromJson(saveData)
-        : QJsonDocument::fromBinaryData(saveData));
+        : QJsonDocument(QCborValue::fromCbor(saveData).toMap().toJsonObject()));
 
     read(loadDoc.object());
 
     QTextStream(stdout) << "Loaded save for "
                         << loadDoc["player"]["name"].toString()
                         << " using "
-                        << (saveFormat != Json ? "binary " : "") << "JSON...\n";
+                        << (saveFormat != Json ? "CBOR" : "JSON") << "...\n";
     return true;
 }
 //! [3]
@@ -148,10 +150,9 @@ bool Game::saveGame(Game::SaveFormat saveFormat) const
 
     QJsonObject gameObject;
     write(gameObject);
-    QJsonDocument saveDoc(gameObject);
     saveFile.write(saveFormat == Json
-        ? saveDoc.toJson()
+        ? QJsonDocument(gameObject).toJson()
-        : saveDoc.toBinaryData());
+        : QCborValue::fromJsonValue(gameObject).toCbor());
 
     return true;
 }

src/corelib/serialization/qjsondocument.cpp

@@ -237,7 +237,7 @@ QJsonDocument &QJsonDocument::operator =(const QJsonDocument &other)
   the application.
   */
 
-#if QT_CONFIG(binaryjson)
+#if QT_CONFIG(binaryjson) && QT_DEPRECATED_SINCE(5, 15)
 /*!
  Creates a QJsonDocument that uses the first \a size bytes from
  \a data. It assumes \a data contains a binary encoded JSON document.
@@ -385,10 +385,13 @@ QJsonDocument QJsonDocument::fromBinaryData(const QByteArray &data, DataValidati
 QByteArray QJsonDocument::toBinaryData() const
 {
     int size = 0;
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
     const char *raw = rawData(&size);
+QT_WARNING_POP
     return QByteArray(raw, size);
 }
-#endif // QT_CONFIG(binaryjson)
+#endif // QT_CONFIG(binaryjson) && QT_DEPRECATED_SINCE(5, 15)
 
 /*!
  Creates a QJsonDocument from the QVariant \a variant.

src/corelib/serialization/qjsondocument.h

@@ -111,13 +111,19 @@ public:
         BypassValidation
     };
 
-#if QT_CONFIG(binaryjson)
+#if QT_CONFIG(binaryjson) && QT_DEPRECATED_SINCE(5, 15)
+    QT_DEPRECATED_X("Use CBOR format instead")
     static QJsonDocument fromRawData(const char *data, int size, DataValidation validation = Validate);
+
+    QT_DEPRECATED_X("Use CBOR format instead")
     const char *rawData(int *size) const;
 
+    QT_DEPRECATED_X("Use CBOR format instead")
     static QJsonDocument fromBinaryData(const QByteArray &data, DataValidation validation  = Validate);
+
+    QT_DEPRECATED_X("Use CBOR format instead")
     QByteArray toBinaryData() const;
-#endif // QT_CONFIG(binaryjson)
+#endif // QT_CONFIG(binaryjson) && QT_DEPRECATED_SINCE(5, 15)
 
     static QJsonDocument fromVariant(const QVariant &variant);
     QVariant toVariant() const;

src/gui/rhi/qshaderdescription.cpp

@@ -342,8 +342,11 @@ bool QShaderDescription::isValid() const
  */
 QByteArray QShaderDescription::toBinaryJson() const
 {
-#if QT_CONFIG(binaryjson)
+#if QT_CONFIG(binaryjson) && QT_DEPRECATED_SINCE(5, 15)
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
     return d->makeDoc().toBinaryData();
+QT_WARNING_POP
 #else
     qWarning("Cannot generate binary JSON from QShaderDescription due to disabled binaryjson feature");
     return QByteArray();
@@ -382,8 +385,11 @@ QByteArray QShaderDescription::toJson() const
 QShaderDescription QShaderDescription::fromBinaryJson(const QByteArray &data)
 {
     QShaderDescription desc;
-#if QT_CONFIG(binaryjson)
+#if QT_CONFIG(binaryjson) && QT_DEPRECATED_SINCE(5, 15)
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
     QShaderDescriptionPrivate::get(&desc)->loadDoc(QJsonDocument::fromBinaryData(data));
+QT_WARNING_POP
 #else
     Q_UNUSED(data);
     qWarning("Cannot load QShaderDescription from binary JSON due to disabled binaryjson feature");