Changes to state in view_submission and block_action payloads

Published: Tuesday, September 15, 2020
APIs

If you rely or want to rely on stateful Block Kit views, we have some exciting news for you. The payloads for view_submission and block_actions will have some new additions. Read on to learn more.


What's changing

Changes to view_submission payloads

Previously, when your app received a view_submission payload, the state value would only contain the state of any input blocks in the view. This meant that you were missing the state of any stateful elements in other interactive blocks from that view.

From September 29, 2020, view_submission and block_action payloads will include a full state property that will include all stateful elements, not just input blocks.

Below is a sample payload from a modal with a multi_conversations_select element in a section block and a plain_text_input element in an input block:

{
	"state": {
		"values": {
			"section_block_id": {
				"multi_convos": {
					"type": "multi_conversations_select",
					"selected_conversations": ["G12345"]
				}
			},
			"input_block_id": {
				"plain_text_action_id": {
					"type": "plain_text_input",
					"value": "test123"
				}
			}
		}
	}
}

You'll notice how the multi_conversations_select is present now, even though it’s in a section block.

Changes to block_actions payloads

We will also include the state field in all block_actions payloads. You will no longer need to wait for a view_submission to see the full state of your modals, messages, or App Home tabs.

In the example below, this sample payload will be sent when a user selects a conversation, firing a block_actions call:

{
	"actions": [
		{
			"type": "multi_conversations_select",
			"action_id": "multi_convos",
			"block_id": "test123",
			"selected_conversations": ["G12345"]
		}
	],
	"container": {
		"type": "view",
		"view_id": "V12345"
	},
	"state": {
		"values": {
			"section_block_id": {
				"multi_convos": {
					"type": "multi_conversations_select",
					"selected_conversations": ["G12345"]
				}
			},
			"other_block_id": {
				"other_action_id": {
					"type": "plain_text_input",
					"value": "test123"
				}
			}
		}
	}
}

Changes to empty state in all payloads

We’ll send null as the value when users have deselected or deleted their entry in an input or action block.

multi_select elements and checkboxes are exceptions—if you deselect everything in those elements, we send it as [] — an empty array.

You will see these changes in view_submission and block_actions payloads.

In this example, this sample payload will be sent if a user submits a form without selecting any conversations or entering any text:

{
	"state": {
		"values": {
			"section_block_id": {
				"multi_convos": {
					"type": "multi_conversations_select",
					"selected_conversations": []
				}
			},
			"other_block_id": {
				"other_action_id": {
					"type": "plain_text_input",
					"value": null
				}
			}
		}
	}
}

Notice the explicit null and empty [] array.

How to prepare

We don't anticipate this change to break any existing apps—however you should still prepare your app for the addition of the state field in view_submission and block_actions payloads.

Note: It's safe to rely on state for all inputs now, especially if you've used private_metadata as a stand-in for maintaining their state.

What happens if I do nothing?

Since this change is additive it should be backwards-compatible, because it's not changing the existing structure of the payload. If your app assumes state will only be included in user-modified input blocks, you may want to verify how your app will respond to these changes.

When is this happening?

The updated payloads mentioned above will be sent to apps from September 29, 2020. Please contact us with any concerns at feedback@slack.com.

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