Support Slack Blocks

[nzlosh]

Add support to the backend chat adapter. This feature may also require updating errbot's slack backend code.

https://api.slack.com/messaging/attachments-to-blocks

[nzlosh]

StackStorm/hubot-stackstorm#166

[nzlosh]

https://github.com/errbotio/errbot/issues/1319

[bloodywing]

from errbot import BotPlugin
from errbot.backends.base import Identifier
from pprint import pformat

class SlackBlocks(BotPlugin):

    def block(self, to: Identifier, blocks: []):
        self.log.debug('blocks: %s' % pformat(blocks))
        if self._bot.mode == 'slack':
            self._bot.api_call('chat.postMessage', data={
                'channel': to,
                'as_user': True,
                'attachments': [
                    {
                        "blocks": blocks
                    }
                ]
            })

I made a plugin which does something like that, it takes the blocks as dictionary. Slack is a bit wonky regarding the blocks and empty strings cause issues. I'll make it a full plugin when I tested this more. The to parameter is something like: self.build_identifier('#mychannel') When you write your plugin use the SlackBlocks as DependsOn and you can use it in your own Plugin.

The blocks list is what Slack shows you in the blockbuilder on their site.

[nzlosh]

@bloodywing Thank you for sharing your implementation. 👍 I finally got around to implementing this and your example was useful.