Mapping: Appending to list, Adding to dictionary

[josephfinlayson]

I'm trying to map between two resources

class AirtableShopifyMapper(odin.Mapping):

    from_resource = AirTableProduct
    to_resource = ShopifyProduct

    @odin.map_list_field(from_field='wholesale_price', to_field='metafields')
    def wholesale_price(self, value):
        return ["wholesale_price"]

    
    @odin.map_list_field(from_field='sample_price', to_field='metafields')
    def sample_price (self, value):
        return ["sample_price"]

Specifically, I want to find out how to append to a field on the to_resource I can't work out how to do this. I've tried to access the to_object.metafields on self to keep appending, but I don't see it avaiable. Any tips?

[timsavage]

Mapping rules are used to build up a dictionary of keywords that are applied to a new resource instance, this doesn't allow for fields to be appended to, however, a mapping rule can accept multiple inputs allowing for your mapping to be defined as:

class AirTableProductToShopifyProduct(odin.Mapping):

    from_resource = AirTableProduct
    to_resource = ShopifyProduct

    @odin.map_list_field(from_field=('wholesale_price', 'sample_price')
    def metafields(self, wholesale_price, sample_price):
        return [wholesale_price, sample_price]

[timsavage]

See the examples in the mapping docs.
https://odin.readthedocs.io/en/latest/ref/mapping/classes.html#applying-transformations-to-data

[josephfinlayson]

Thank you, ideally for me there would be a way to have independent mappers to append to the list. I have 20 input fields, that need to be appended to this list.

To make the code more testable and maintainable, it would be useful to have a way of defining independent mappers, that append to the list. I will close this for now, but please consider this feature. Thanks!

[timsavage]

I've been thinking about how that would be achieved effectively, as this is a bit of a special case I'm loath to add more complexity and change the behaviour of the internals of mappers to maintain compatibility with existing usage.

One possible solution would be a "combining rule" that can append the results of several rules (internally a field mapping is defined as the action on a mapping rule) before returning the final result. This would allow for more flexibility without needing to modify the internals of mappers.

I'm going to re-open this issue as a feature request.