datalad.api.meta_filter(filtername: str, metadataurls: List[Union[str, datalad_metalad.pathutils.metadataurlparser.MetadataURL]], dataset: Union[datalad.distribution.dataset.Dataset, str, None] = '.', filterargs: Optional[List[str]] = None, recursive: bool = False) → Iterable[T_co]

Run a metadata filter on a set of metadata elements.

Take a number of metadata elements and run a filter on it.

The result of the filter operation will be written to stdout and can, for example, be passed to meta-add.

The filter can be configured by passing key-value pairs given as additional arguments. Each key-value pair consists of two arguments, first the key, then the value. The key value pairs have to be separated by ‘++’ from the metadata coordinates


  • filtername (str) – Name of the filter that should be executed.
  • metadataurls (non-empty sequence of str) – MetadataRecord URL(s). A list of at least one metadata URL. The filter will receive a list of iterables, that contains one iterable for each metadata URL. The iterables will yields all metadata- entries that match the respective metadata URL.
  • dataset (Dataset or None, optional) – Git repository that contains datalad metadata. If no repository path is given, the metadata store is determined by the current work directory. All metadata URLs (see below) are relative to this dataset. [Default: ‘.’]
  • filterargs (sequence of str or None, optional) – Extractor arguments given as string arguments to the extractor. Filter arguments have to be separated from the list of metadata coordinates by ‘++’. [Default: None]
  • recursive (bool, optional) – If set, the metadata URL iterables will yield all metadata recursively from the matching metadata URLs. [Default: False]
  • on_failure ({'ignore', 'continue', 'stop'}, optional) – behavior to perform on failure: ‘ignore’ any failure is reported, but does not cause an exception; ‘continue’ if any failure occurs an exception will be raised at the end, but processing other actions will continue for as long as possible; ‘stop’: processing will stop on first failure and an exception is raised. A failure is any result with status ‘impossible’ or ‘error’. Raised exception is an IncompleteResultsError that carries the result dictionaries of the failures in its failed attribute. [Default: ‘continue’]
  • result_filter (callable or None, optional) – if given, each to-be-returned status dictionary is passed to this callable, and is only returned if the callable’s return value does not evaluate to False or a ValueError exception is raised. If the given callable supports **kwargs it will additionally be passed the keyword arguments of the original API call. [Default: None]
  • result_renderer – select rendering mode command results. ‘tailored’ enables a command- specific rendering style that is typically tailored to human consumption, if there is one for a specific command, or otherwise falls back on the the ‘generic’ result renderer; ‘generic’ renders each result in one line with key info like action, status, path, and an optional message); ‘json’ a complete JSON line serialization of the full result record; ‘json_pp’ like ‘json’, but pretty-printed spanning multiple lines; ‘disabled’ turns off result rendering entirely; ‘<template>’ reports any value(s) of any result properties in any format indicated by the template (e.g. ‘{path}’, compare with JSON output for all key-value choices). The template syntax follows the Python “format() language”. It is possible to report individual dictionary values, e.g. ‘{metadata[name]}’. If a 2nd-level key contains a colon, e.g. ‘music:Genre’, ‘:’ must be substituted by ‘#’ in the template, like so: ‘{metadata[music#Genre]}’. [Default: ‘tailored’]
  • result_xfm ({'datasets', 'successdatasets-or-none', 'paths', 'relpaths', 'metadata'} or callable or None, optional) – if given, each to-be-returned result status dictionary is passed to this callable, and its return value becomes the result instead. This is different from result_filter, as it can perform arbitrary transformation of the result value. This is mostly useful for top- level command invocations that need to provide the results in a particular format. Instead of a callable, a label for a pre-crafted result transformation can be given. [Default: None]
  • return_type ({'generator', 'list', 'item-or-list'}, optional) – return value behavior switch. If ‘item-or-list’ a single value is returned instead of a one-item return value list, or a list in case of multiple return values. None is return in case of an empty list. [Default: ‘list’]