Define Import Handler

The obvious step here is to define a new import handler, which ultimately inherits from ImportHandler. But the choice of which class(es) specifically to inherit from, is a bit more complicated.

Choose the Base Class(es)

If all else fails, or to get started simply, you can always just inherit from ImportHandler directly as the only base class. You’ll have to define any methods needed to implement desired behavior.

However depending on your particular source and/or target, there may be existing base classes defined somewhere from which you can inherit. This may save you some effort, and/or is just a good idea to share code where possible.

Keep in mind your import handler can inherit from multiple base classes, and often will - one base for the source side, and another for the target side. For instance:

from wuttasync.importing import FromFileHandler, ToWuttaHandler

class FromExcelToPoser(FromFileHandler, ToWuttaHandler):
    """
    Handler for Excel file → Poser app DB
    """

You generally will still need to define/override some methods to customize behavior.

All built-in base classes live under wuttasync.importing.

Register Importer(s)

If nothing else, most custom handlers must override define_importers() to “register” importer(s) as appropriate. There are two primary goals here:

• add “new” (totally custom) importers

• override “existing” importers (inherited from base class)

Obviously for this to actually work the importer(s) must exist in code; see Define Importer(s).

As an example let’s say there’s a FromFooToWutta handler which defines a Widget importer.

And let’s say you want to customize that, by tweaking slightly the logic for WigdetImporter and adding a new SprocketImporter:

from somewhere_else import (FromFooToWutta, ToWutta,
                            WidgetImporter as WidgetImporterBase)

class FromFooToPoser(FromFooToWutta):
    """
    Handler for Foo -> Poser
    """

    def define_importers(self):

        # base class defines the initial set
        importers = super().define_importers()

        # override widget importer
        importers['Widget'] = WidgetImporter

        # add sprocket importer
        importers['Sprocket'] = SprocketImporter

        return importers

class SprocketImporter(ToWutta):
    """
    Sprocket importer for Foo -> Poser
    """

class WidgetImporter(WidgetImporterBase):
    """
    Widget importer for Foo -> Poser
    """