chain.rst

Chain Loader

The Chain data loader doesn't load the image binary itself; instead it allows for loading the image binary using any number of other configured data loaders. For example, if you configured both a filesystem <data-loaders-filesystem> and flysystem <data-loaders-flysystem> data loader, this loader can be defined to load from both in a defined order, returning the image binary from the first that responds.

Tip

This loader iterates over the data loaders in the order they are configured in the chain definition, returning an image binary from the first loader that supports the passed file path. This means if a file exists in more than one loader, the file will be returned using the first one defined in your configuration file for this chain loader.

Configuration

As this loader leverages any number of other configured loaders, its configuration is relatively simple; it supports only a loaders option that accepts an array of other configured loader names:

# app/config/config.yml

liip_imagine:
    loaders:
        foo:
            filesystem:
                # configure filesystem loader

        bar:
            flysystem:
                # configure flysystem loader

        baz:
            stream:
                # configure stream loader

        qux:
            chain:
                # use the "foo", "bar", and "baz" loaders
                loaders:
                    - foo
                    - bar
                    - baz