Add a stac_io argument in Catalog.save?

[fnattino]

It is nice how the STAC I/O has been refactored, with the possibility for the user to provide customised StacIO instances as argument to StacObject.save_object (or ItemCollection.save_object).

But shouldn't the catalog Catalog.save method also accept a stac_io argument to optionally specify the StacIO to recursively write out all children and items?

If you agree, I would be happy to contribute with a PR!

[fnattino]

I see that if one reads a catalog with a user-defined StacIO instance this is stored internally as catalog._stac_io so that this is used in later calls to Catalog.save(dest_href). But what if one wants to use a different StacIO instance for writing? I guess this could happen if one is reading from/writing to different filesystem types.

[thomafred]

StacIO's abstract member functions read_text and write_text are called by read_stac_object and save_json respectively. This allows for custom file formats, but is limiting as it does not enable the ability to use alternative protocols. This is actually mentioned in the docs:

# stac_io.py:324
This implementation uses :func:`open` and therefore can only write to the local
file system.

Personally, I think that StacIO should only contain two abstract functions:

# Essentially the same as current implementation
def read_stac_object(
    self,
    source: Union[str, "Link_Type"],
    root: Optional["Catalog_Type"] = None,
    *args: Any,
    **kwargs: Any,
) -> "STACObject_Type"

def write_stac_object(
        self,
        dest: Union[str, "Link_Type"],
        stac_object: "STACObject_Type",
        *args: Any,
        **kwargs: Any,
    ) -> None

This would create explicit entry-points for IO-operations and enable develops to easily create custom integrations for APIs and custom file protocols.

[duckontheweb]

It is nice how the STAC I/O has been refactored, with the possibility for the user to provide customised StacIO instances as argument to StacObject.save_object (or ItemCollection.save_object).

But shouldn't the catalog Catalog.save method also accept a stac_io argument to optionally specify the StacIO to recursively write out all children and items?

If you agree, I would be happy to contribute with a PR!

@fnattino I would support adding a stac_io argument to Catalog.save and would be happy to review a PR! I agree that needing to read and write using different protocols/file systems is a common enough use case that we should make it convenient to do.

[fnattino]

Apologies for the long delay with this - if still in time I can open a PR before the end of the week.