How to convert Qt file path from resource to absolute path?

Question

I need to receive the absolute file path like

C:/Users/Dima/YandexDisk/_Application/WeldAnalysis/ExperimentDefaults.xlsx

from path of QRC file like

:/Data/ExperimentDefaults.xlsx.

How can I do this?

Answer 1

Resources are packed all together into the QRC file, they are not exposed to the filesystem, thus they cannot be converted to a standard path; it is like accessing a file inside a zip file.

What are you willing to do with such file path? QFile can deal with resource paths (":/...") and open such files, but other file handling APIs don't (such as C's fopen or C++'s std::ifstream). Also, and for the same reason, non-Qt application won't be able to open such files if passed as a parameter.

Options you have include:

• opening the file using QFile and read it using related Qt classes (given you are dealing with an Excel file I think it doesn't worth the effort, unless you have some library to read it from a memory buffer).

• copying the file out of the resources container to a temporary directory (you can use QTemporaryDir to create one), and use the file from there:

  QTemporaryDir tempDir;
  if (tempDir.isValid()) {
    const QString tempFile = tempDir.path() + "/yourfile.xlsx";
    if (QFile::copy(":/yourfile.xlsx", tempFile)) {
      // your file is now extracted to the filesystem
    }
  }
  

Only be aware that when tempDir is destroyed, the temporary directory is also deleted, therefore your file. You can avoid this by disabling the auto-remove feature: tempDir.setAutoRemove(false) and manually deleting the temporary directory when you finish with the extracted file.