FileDownloader

Qualified name: mv::util::FileDownloader

class FileDownloader : public QObject

File downloader class.

Helper class for simplifying file download

Author

Thomas Kroes

Public Static Functions

static SecureNetworkAccessManager &sharedManager()

Get the shared network access manager instance.

Returns:

Reference to the shared QNetworkAccessManager instance

static QFuture<QByteArray> downloadToByteArrayAsync(const QUrl &url, Task *task = nullptr)

Download file to byte array asynchronously.

Parameters:

  • url – URL of the file to download

  • task – Optional task to associate with the download operation (must live in the main/GUI thread)

Returns:

Future containing the downloaded data as byte array

static QFuture<QString> downloadToFileAsync(const QUrl &url, const QString &targetDirectory = "", Task *task = nullptr, bool overwriteAllowed = true)

Download file from url to targetDirectory asynchronously.

Parameters:

  • url – URL of the file to download

  • targetDirectory – Directory where the file should be saved (OS temporary dir when empty)

  • task – Optional task to associate with the download operation (must live in the main/GUI thread)

  • overwriteAllowed – Whether it is ok to overwrite existing download

Returns:

Future containing the path to the downloaded file

static QFuture<std::uint64_t> getDownloadSizeAsync(const QUrl &url)

Get the size of the file to be downloaded asynchronously.

Parameters:

url – URL of the file to be downloaded

Returns:

Size of the file to be downloaded in bytes, 0 if size cannot be determined

static QFuture<QDateTime> getLastModifiedAsync(const QUrl &url)

Get the last modified date of the file at url asynchronously.

Parameters:

url – URL of the file to check

Returns:

Last modified date of the file, QDateTime() if it cannot be determined

static QFuture<QString> getFinalFileNameAsync(const QUrl &url)

Get the final file name of the file at url asynchronously (works with redirected URL)

Parameters:

url – URL of the file to check

Returns:

QFuture that will contain the final file name of the file, or an empty string if it cannot be determined

class ByteArraySink : public mv::util::FileDownloader::ISink<QByteArray>

Saves the download to a byte array.

Public Functions

virtual bool open(QNetworkReply *reply, const QUrl &url, const QString &targetDirectory, bool overwriteAllowed, QString *error) override

Finalize successfully (e.g., commit QSaveFile)

Parameters:

  • reply – Pointer to network reply (may not be nullptr)

  • url – Url to download

  • targetDirectory – Target directory where to put the download

  • overwriteAllowed – Whether it is allowed to overwrite an existing download

  • error – Pointer to error

Returns:

Whether successfully opened

virtual bool write(const QByteArray &chunk, QString *error) override

Write chunk with error.

Parameters:

  • chunk – Chunk of data

  • error – Pointer to error

Returns:

Whether successfully written

virtual bool commit(QString *error) override

Finalize successfully (e.g., commit QSaveFile)

Parameters:

error – Pointer to error

Returns:

Whether commit was successful

virtual void cancel() noexcept override

Discards partial output.

virtual QByteArray result() const override

Get the resulting value to emit into the promise.

Returns:

The promise result

class Exception : public mv::util::BaseException

Exception class for file downloader issues.

Public Functions

explicit Exception(const QString &message)

Construct with message.

Parameters:

message – Message describing the download issue

class FileSink : public mv::util::FileDownloader::ISink<QString>

Saves the download to a file on disk.

Public Functions

virtual bool open(QNetworkReply *reply, const QUrl &url, const QString &targetDirectory, bool overwriteAllowed, QString *error) override

Finalize successfully (e.g., commit QSaveFile)

Parameters:

  • reply – Pointer to network reply (may not be nullptr)

  • url – Url to download

  • targetDirectory – Target directory where to put the download

  • overwriteAllowed – Whether it is allowed to overwrite an existing download

  • error – Pointer to error

Returns:

Whether successfully opened

virtual bool write(const QByteArray &chunk, QString *error) override

Write chunk with error.

Parameters:

  • chunk – Chunk of data

  • error – Pointer to error

Returns:

Whether successfully written

virtual bool commit(QString *error) override

Finalize successfully (e.g., commit QSaveFile)

Parameters:

error – Pointer to error

Returns:

Whether commit was successful

virtual void cancel() noexcept override

Discards partial output.

virtual QString result() const override

Get the resulting value to emit into the promise.

Returns:

The promise result

template<typename T>
struct ISink

Public Functions

virtual bool open(QNetworkReply *reply, const QUrl &url, const QString &targetDirectory, bool overwriteAllowed, QString *error) = 0

Finalize successfully (e.g., commit QSaveFile)

Parameters:

  • reply – Pointer to network reply (may not be nullptr)

  • url – Url to download

  • targetDirectory – Target directory where to put the download

  • overwriteAllowed – Whether it is allowed to overwrite an existing download

  • error – Pointer to error

Returns:

Whether successfully opened

virtual bool write(const QByteArray &chunk, QString *error) = 0

Write chunk with error.

Parameters:

  • chunk – Chunk of data

  • error – Pointer to error

Returns:

Whether successfully written

virtual bool commit(QString *error) = 0

Finalize successfully (e.g., commit QSaveFile)

Parameters:

error – Pointer to error

Returns:

Whether commit was successful

virtual void cancel() noexcept = 0

Discards partial output.

virtual Result result() const = 0

Get the resulting value to emit into the promise.

Returns:

The promise result