'Return all fields as normal, with one exception: replace every instance
of TranslationSerializerField with ESTranslationSerializerField.'

def get_fields(self):

    fields = super(BaseESSerializer, self).get_fields()
    for (key, field) in fields.items():
        if isinstance(field, TranslationSerializerField):
            fields[key] = ESTranslationSerializerField(source=field.source)
    return fields
