Build Adapter from DataSource

build_adapter.py

import collections

from tiled.mimetypes import DEFAULT_ADAPTERS_BY_MIMETYPE


def build_adapter(data_source, adapters_by_mimetype=None):
    # We use a dictionary mapping a mimetype to a callable that returns an Adapter instance.
    # This might be a class, classmethod constructor, factory function...
    # it does not matter here; it is just a callable.
    
    # User-provided adapters take precedence over defaults.
    merged_adapters_by_mimetype = collections.ChainMap(
      (adapters_by_mimetype or {}),
      DEFAULT_ADAPTERS_BY_MIMETYPE,
    )
    adapter_factory = merged_adapters_by_mimetype[data_source.mimetype]
    
    # Construct kwargs to pass to Adapter.
    parameters = collections.defaultdict(list)
    for asset in data_source.assets:
        if asset.parameter is None:
            # This asset is not directly opened by the Adapter.
            # It is used indirectly, such as the case of HDF5 virtual dataset
            # 'data' files are referenced from 'master' files.
            continue
        if asset.num is None:
            # This parameters takes the URI as a scalar value.
            parameters[asset.parameter] = asset.data_uri
        else:
            # This parameters takes a list of URIs.
            parameters[asset.parameter].append(asset.data_uri)
    adapter_kwargs = dict(parameters)
    adapter_kwargs.update(data_source.parameters)
    
    adapter = adapter_factory(**adapter_kwargs)
    return adapter