Messages

Payload factories for Web API messages, webhooks, and interaction responses.

attachment()

attachment(input, settings?): JsonObject

Creates lower-priority supporting content using Slack's legacy secondary-attachment format.

Attachments can add context beneath a message, while fallback supplies a plain-text summary for notifications and clients that cannot display Block Kit.

Input fields

Attachment blocks plus optional color and fallback text.

Input field	Type	Description
blocks	JsonObject[]	Blocks displayed inside the attachment.
color?	string	Optional side-border color: a Color value or a six-digit hex code.
fallback?	string	Plain-text fallback for notifications and clients without Block Kit support.

Settings

Setting	Type	Description
settings	FactorySettings	Per-call validation settings.

Returns

JsonObject

A Slack attachment object.

Throws

InvalidUsageError when the color is not a valid hex code or a nested block violates a supported Block Kit constraint.

See

https://docs.slack.dev/legacy/legacy-messaging/legacy-secondary-message-attachments

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Color

const Color: object

Preset side-border colors for legacy attachments.

The values mirror the Python Color enum: three Slack-recognized aliases (good, warning, danger) plus common hex colors.

Type Declaration

Name	Type	Default value
BLACK	"#000000"	"#000000"
BLUE	"#0000ff"	"#0000ff"
DANGER	"danger"	"danger"
GOOD	"good"	"good"
GREEN	"#00ff00"	"#00ff00"
ORANGE	"#ff8800"	"#ff8800"
PURPLE	"#8800ff"	"#8800ff"
RED	"#ff0000"	"#ff0000"
WARNING	"warning"	"warning"
YELLOW	"#ffff00"	"#ffff00"

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message()

message(input, settings?): JsonObject

Creates a payload for Slack Web API message methods such as chat.postMessage.

Input fields

Destination channel and message content.

Input field	Type	Description
attachments?	JsonObject[]	Optional secondary attachments.
blocks?	JsonObject[]	Block Kit blocks displayed in the message.
channel	string	Channel, group, or direct-message conversation identifier.
metadata?	JsonObject	Optional message metadata.
mrkdwn?	boolean	Whether Slack parses text as mrkdwn. Defaults to true.
text?	string	Notification and accessibility fallback text.
unfurlLinks?	boolean	Whether Slack unfurls links.
unfurlMedia?	boolean	Whether Slack unfurls media.

Settings

Setting	Type	Description
settings	FactorySettings	Per-call validation settings.

Returns

JsonObject

A Slack-shaped message payload ready to spread into an SDK call.

Throws

InvalidUsageError when nested Block Kit content is invalid.

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MessageInput

Fields accepted by message.

Properties

Property	Type	Description
attachments?	JsonObject[]	Optional secondary attachments.
blocks?	JsonObject[]	Block Kit blocks displayed in the message.
channel	string	Channel, group, or direct-message conversation identifier.
metadata?	JsonObject	Optional message metadata.
mrkdwn?	boolean	Whether Slack parses text as mrkdwn. Defaults to true.
text?	string	Notification and accessibility fallback text.
unfurlLinks?	boolean	Whether Slack unfurls links.
unfurlMedia?	boolean	Whether Slack unfurls media.

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messageResponse()

messageResponse(input, settings?): JsonObject

Creates a response payload for slash commands and interactive requests.

Input fields

Response content, visibility, and replacement behavior.

Input field	Type	Description
attachments?	JsonObject[]	Optional secondary attachments.
blocks?	JsonObject[]	Block Kit blocks displayed in the response.
mrkdwn?	boolean	Whether Slack parses text as mrkdwn. Defaults to true.
replaceOriginal?	boolean	Replace the original interaction message. Defaults to false.
responseType?	"ephemeral" | "in_channel"	Response visibility. Defaults to in_channel.
text?	string	Notification and accessibility fallback text.

Settings

Setting	Type	Description
settings	FactorySettings	Per-call validation settings.

Returns

JsonObject

A Slack interaction-response payload.

Throws

InvalidUsageError when nested Block Kit content is invalid.

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webhookMessage()

webhookMessage(input, settings?): JsonObject

Creates a payload for an incoming webhook or response URL.

Input fields

Message content, visibility, replacement behavior, and unfurl settings.

Input field	Type	Description
attachments?	JsonObject[]	Optional secondary attachments.
blocks?	JsonObject[]	Block Kit blocks displayed in the message.
deleteOriginal?	boolean	Delete the original interaction message.
metadata?	JsonObject	Optional message metadata.
replaceOriginal?	boolean	Replace the original interaction message.
responseType?	"ephemeral" | "in_channel"	Response visibility for response URLs.
text?	string	Notification and accessibility fallback text.
unfurlLinks?	boolean	Whether Slack unfurls links.
unfurlMedia?	boolean	Whether Slack unfurls media.

Settings

Setting	Type	Description
settings	FactorySettings	Per-call validation settings.

Returns

JsonObject

A Slack webhook-message payload.

Throws

InvalidUsageError when nested Block Kit content is invalid.