pathlib support for file constructor arguments

[ltalirz]

Is your feature request related to a problem? Please describe

In [1]: from aiida.orm import SinglefileData

In [2]: !pwd
/Users/leopold

In [3]: s=SinglefileData(file='/Users/leopold/nanopub.zip')

In [4]: from pathlib import Path

In [5]: s=SinglefileData(file=Path('/Users/leopold/nanopub.zip'))
-------------------------------------------------------------------------
AttributeError                          Traceback (most recent call last)
<ipython-input-5-e5ace348d29f> in <module>
----> 1 s=SinglefileData(file=Path('/Users/leopold/nanopub.zip'))

~/Personal/Postdoc-MARVEL/repos/aiida/aiida_rmq/aiida/orm/nodes/data/singlefile.py in __init__(self, file, filename, **kwargs)
     45             if filename is None:
     46                 # don't assume that set_file has a 'filename' argument (remove guard in 2.0.0)
---> 47                 self.set_file(file)
     48             else:
     49                 self.set_file(file, filename=filename)

~/Personal/Postdoc-MARVEL/repos/aiida/aiida_rmq/aiida/orm/nodes/data/singlefile.py in set_file(self, file, filename)
    130
    131         if is_filelike:
--> 132             self.put_object_from_filelike(file, key, mode='wb')
    133         else:
    134             self.put_object_from_file(file, key)

~/Personal/Postdoc-MARVEL/repos/aiida/aiida_rmq/aiida/orm/nodes/node.py in put_object_from_filelike(self, handle, path, mode, encoding, force, key)
    637             raise TypeError("put_object_from_filelike() missing 1 required positional argument: 'path'")
    638
--> 639         self._repository.put_object_from_filelike(handle, path, mode, encoding, force)
    640
    641     def delete_object(self, path=None, force=False, key=None):

~/Personal/Postdoc-MARVEL/repos/aiida/aiida_rmq/aiida/orm/utils/_repository.py in put_object_from_filelike(self, handle, key, mode, encoding, force)
    229             folder = folder.get_subfolder(basepath, create=True)
    230
--> 231         folder.create_file_from_filelike(handle, key, mode=mode, encoding=encoding)
    232
    233     def delete_object(self, key, force=False):

~/Personal/Postdoc-MARVEL/repos/aiida/aiida_rmq/aiida/common/folders.py in create_file_from_filelike(self, filelike, filename, mode, encoding)
    226
    227         with open(filepath, mode=mode, encoding=encoding) as handle:
--> 228             shutil.copyfileobj(filelike, handle)
    229
    230         os.chmod(filepath, self.mode_file)

~/Applications/miniconda3/envs/aiida_rmq_py3/lib/python3.7/shutil.py in copyfileobj(fsrc, fdst, length)
     77     """copy data from file-like object fsrc to file-like object fdst"""
     78     while 1:
---> 79         buf = fsrc.read(length)
     80         if not buf:
     81             break

AttributeError: 'PosixPath' object has no attribute 'read'

Describe the solution you'd like

We should start supporting pathlib.Path objects, wherever we accept paths in string form.

[greschd]

Maybe we can just revive #3614.

[ltalirz]

Oops - I searched for issues but didn't find one ;-)

Thanks @greschd , feel free to put me as a reviewer

[greschd]

It's because it was a PR, not an issue ;)