Allow overriding the cache location via Synapse() constructor

[sage-bionetworks]

Allow overriding the cache location via Synapse() constructor

[jkiang13]

@keller-mark Thanks for the suggestion. So I understand the general need, you'd like to be able to use downloadTableColumns to download to an alternate path than the default cache. Would something like an optional downloadLocation parameter on downloadTableColumns similar to syn.get also satisfy this requirement?

In the meantime, something like the following utility method might be useful as a workaround:

import configparser
import synapseclient
import tempfile


def synapse_custom_cache_dir(cache_dir):
    """Return a new Synapse instance with the given cache directory as its configured cache root"""

    config = configparser.RawConfigParser()
    config.read(synapseclient.client.CONFIG_FILE)

    if not config.has_section('cache'):
        config.add_section('cache')
    config['cache']['location'] = cache_dir

    with tempfile.NamedTemporaryFile(mode='w') as tempconfig:
        config.write(tempconfig)
        tempconfig.flush()

        return synapseclient.Synapse(configPath=tempconfig.name)

Sample usage:

syn = synapse_custom_cache_dir('/path/to/location1')
syn.login()
results = syn.tableQuery('SELECT * FROM syn123 LIMIT 5')
syn.downloadTableColumns(results, ['foo', 'bar'])

syn = synapse_custom_cache_dir('/path/to/location2')
syn.login()
results = syn.tableQuery('SELECT * FROM syn456 LIMIT 5')
syn.downloadTableColumns(results, ['foo', 'bar'])

[keller-mark]

A downloadLocation parameter would be great. Thanks for the workaround.