Container block

Fields

Field	Type	Description	Required?
type	String	The type of block. For a container block, type is always container.	Required
title	String	Title of the container, using plain_text formatting. Maximum of 150 characters.	Optional (one of title or rich_text_title is required)
rich_text_title	String	The title for the container as a rich_text block. If both title and rich_text_title are provided, rich_text_title takes precedence.	Optional (one of title or rich_text_title is required)
subtitle	String	Subtitle of the container, using plain_text or mrkdwn formatting. Maximum of 150 characters.	Optional
child_blocks	Array	List of included blocks. Maximum of 10 blocks.	Required
block_id	String	A unique identifier for a block. If not specified, a block_id will be generated.	Optional
width	String	Sets the width of the container block. The narrow, standard, and wide options use a platform-determined constrained width. The full option expands to fill the available space. Default is standard.	Optional
icon	Image element	Link to the small image used next to the card's title and subtitle. Maximum length of 3000 characters. The alt_text property has a maximum length of 2000 characters.	Optional
is_collapsible	Boolean	When true, the block can be collapsed to show only the title. Defaults to false.	Optional
default_collapsed	Boolean	When true and is_collapsible are both true, the block initially renders in a collapsed state. Defaults to false.	Optional
has_header_divider	Boolean	When true, a visible border is rendered below the header to visually separate it from the content. Only applies when the block is not collapsible. Defaults to false.	Optional

Supported child blocks

• actions
• context
• divider
• file
• header
• image
• input
• rich_text
• section
• table
• video

Example

A sample container block:

JSON

{
	"blocks": [
		{
			"type": "container",
			"block_id": "bkb_container_bulk_update",
			"title": {
				"type": "plain_text",
				"text": "Bulk update: 2 records selected"
			},
			"subtitle": {
				"type": "plain_text",
				"text": "Review changes before confirming"
			},
			"is_collapsible": true,
			"child_blocks": [
				{
					"type": "section",
					"block_id": "record-row-1",
					"text": {
						"type": "mrkdwn",
						"text": "*DCW-1024*\nStatus: Open → Closed\nAssignee: @princessdonut → @carl"
					}
				},
				{
					"type": "divider",
					"block_id": "bulk-div-1"
				},
				{
					"type": "section",
					"block_id": "record-row-2",
					"text": {
						"type": "mrkdwn",
						"text": "*DCW-1025*\nStatus: In Progress → Closed\nAssignee: @mordecai → @carl"
					}
				},
				{
					"type": "divider",
					"block_id": "bulk-div-2"
				},
				{
					"type": "context",
					"block_id": "bulk-status-bar",
					"elements": [
						{
							"type": "mrkdwn",
							"text": ":white_check_mark: 2 records will be updated • Status → Closed • Assignee → @carl"
						}
					]
				},
				{
					"type": "actions",
					"block_id": "bulk-actions",
					"elements": [
						{
							"type": "button",
							"text": {
								"type": "plain_text",
								"text": "Confirm All",
								"emoji": true
							},
							"style": "primary",
							"action_id": "bulk_confirm"
						},
						{
							"type": "button",
							"text": {
								"type": "plain_text",
								"text": "Cancel",
								"emoji": true
							},
							"action_id": "bulk_cancel"
						}
					]
				}
			]
		}
	]
}

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