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chat.postEphemeral method

Facts​

DescriptionSends an ephemeral message to a user in a channel.
Method Access
POST https://slack.com/api/chat.postEphemeral
Scopes
Bot token:
User token:
Content types
application/x-www-form-urlencoded
application/json
Rate LimitsTier 4: 100+ per minute

Arguments​

Required arguments

tokenstringRequired

Authentication token bearing required scopes. Tokens should be passed as an HTTP Authorization header or alternatively, as a POST parameter.

Example: xxxx-xxxxxxxxx-xxxx
channelstringRequired

Channel, private group, or IM channel to send message to. Can be an encoded ID, or a name.

userRequired

id of the user who will receive the ephemeral message. The user should be in the channel specified by the channel argument.

Example: U0BPQUNTA

Optional arguments

as_userbooleanOptional

(Legacy) Pass true to post the message as the authed user. Defaults to true if the chat:write:bot scope is not included. Otherwise, defaults to false.

Example: true
attachmentsOptional

A JSON-based array of structured attachments, presented as a URL-encoded string.

Example: [{"pretext": "pre-hello", "text": "text-world"}]
blocksOptional

A JSON-based array of structured blocks, presented as a URL-encoded string.

Example: [{"type": "section", "text": {"type": "plain_text", "text": "Hello world"}}]
icon_emojistringOptional

Emoji to use as the icon for this message. Overrides icon_url.

Example: :chart_with_upwards_trend:
icon_urlstringOptional

URL to an image to use as the icon for this message.

Example: http://lorempixel.com/48/48
link_namesbooleanOptional

Find and link channel names and usernames.

Example: true
markdown_textstringOptional

Accepts message text formatted in markdown. This argument should not be used in conjunction with blocks or text. Limit this field to 12,000 characters.

Example: **This is bold text**
parseOptional

Change how messages are treated. Defaults to none. See below.

Acceptable values: none full mrkdwn false
Example: full
textOptional

How this field works and whether it is required depends on other fields you use in your API call. See below for more detail.

Example: Hello world
thread_tsOptional

Provide another message's ts value to post this message in a thread. Avoid using a reply's ts value; use its parent's value instead. Ephemeral messages in threads are only shown if there is already an active thread.

usernamestringOptional

Set your bot's user name.

Example: My Bot

Usage info​

This method posts an ephemeral message, which is visible only to the assigned user in a specific public channel, private channel, or private conversation.

Ephemeral message delivery is not guaranteed — the user must be currently active in Slack and a member of the specified channel. By nature, ephemeral messages do not persist across reloads, desktop and mobile apps, or sessions. Once the session is closed, ephemeral messages will disappear and cannot be recovered.

Use ephemeral messages to send users context-sensitive messages, relevant to the channel they're detectably participating in. Avoid sending unexpected or unsolicited ephemeral messages.

Text usage: text, blocks or attachments​

The usage of the text field changes depending on whether you're using blocks. If you're using blocks, this is used as a fallback string to display in notifications. If you aren't, this is the main body text of the message. It can be formatted as plain text, or with mrkdwn.

The text field is not enforced as required when using blocks or attachments. However, we highly recommended that you include text to provide a fallback when using blocks, as described above.

Formatting​

Messages are formatted as described in the formatting spec. You can specify values for parse and link_names to change formatting behavior.

The optional attachments argument should contain a JSON-encoded array of attachments.

For more information, see the attachments spec. If you're using a Slack app, you can also use this method to attach message buttons.

For best results, limit the number of characters in the text field to a few thousand bytes at most. Ideally, messages should be short and human-readable, if you need to post longer messages, please consider uploading a snippet instead. (A single message should be no larger than 4,000 bytes.)

Consider reviewing our message guidelines, especially if you're using attachments or message buttons.

Authorship​

How message authorship is attributed varies by a few factors, with some behaviors varying depending on the kinds of tokens you're using to post a message.

Legacy concerns​

Information in the section below applies only to classic apps.

Legacy authorship​

Classic apps using the umbrella bot scope can't request additional scopes to adjust message authorship.

For classic apps, the best way to control the authorship of a message is to be explicit with the as_user parameter.

If you don't use the as_user parameter, chat.postEphemeral will guess the most appropriate as_user interpretation based on the kind of token you're using.

If as_user is not provided at all, then the value is inferred, based on the scopes granted to the caller: If the caller could post with as_user passed as false, then that is how the method behaves; otherwise, the method behaves as if as_user were passed as true.

When as_user is false​

When the as_user parameter is set to false, messages are posted as "bot_messages", with message authorship attributed to the user name and icons associated with theSlack app.

When as_user is true​

Set as_user to true and the authenticated user will appear as the author of the message. Posting as the authenticated user requires the client or the more preferred chat:write:user scopes.

Target channels and users​

You must specify a conversation container (public channel, private channel, or an IM channel) by providing its ID to the channel argument. You also must specify a target user.

Each type of channel behaves slightly differently based on the authenticated user's permissions and additional arguments. If the target user is not in the given channel, the ephemeral message will not be delivered, and we'll return a user_not_in_channel error.

Workspace apps will receive a no_permission error when they are not a member of the specified channel.

Note that the user parameter expects a user's id, and not a username or display name.

Post to a public channel​

You can either pass the channel's name (#general) or encoded ID (C024BE91L), and the message will be posted to that channel. The channel's ID can be retrieved through the conversations.list API method.

Post to a private group​

As long as the authenticated user is a member of the private group, you can either pass the group's name (secret-group) or encoded ID (G012AC86C), and the message will be posted to that group. The private group's ID can be retrieved through the conversations.list API method.

Post to an IM channel​

Posting to an IM channel is a little more complex depending on the value of as_user.

  • If as_user is false:
    • Pass a username (@chris) as the value of channel to post to that user's @slackbot channel as the bot.
    • Pass the IM channel's ID (D023BB3L2) as the value of channel to post to that IM channel as the bot. The IM channel's ID can be retrieved through the conversations.list API method.
  • If as_user is true:
    • Pass the IM channel's ID (D023BB3L2) as the value of channel to post to that IM channel as the authenticated user. The IM channel's ID can be retrieved through the conversations.list API method.

To send a direct message to the user owning the token used in the request, provide the channel field with the a conversation/IM ID value found in a method like conversations.list.

Response​

Typical success response

{
  "ok": true,
  "message_ts": "1502210682.580145"
}

Typical error response

{
  "ok": false,
  "error": "user_not_in_channel"
}

The message_ts included with the response cannot be used with chat.update, as it does not represent an actual message written to the database like it does with other api methods.

Errors​

This table lists the expected errors that this method could return. However, other errors can be returned in the case where the service is down or other unexpected factors affect processing. Callers should always check the value of the ok parameter in the response.

Error
Description
access_denied

Access to a resource specified in the request is denied.

accesslimited

Access to this method is limited on the current network

account_inactive

Authentication token is for a deleted user or workspace when using a bot token.

cannot_reply_to_message

This message type cannot have thread replies.

channel_not_found

Value passed for channel was invalid.

deprecated_endpoint

The endpoint has been deprecated.

ekm_access_denied

Administrators have suspended the ability to post a message.

enterprise_is_restricted

The method cannot be called from an Enterprise.

fatal_error

The server could not complete your operation(s) without encountering a catastrophic error. It's possible some aspect of the operation succeeded before the error was raised.

internal_error

The server could not complete your operation(s) without encountering an error, likely due to a transient issue on our end. It's possible some aspect of the operation succeeded before the error was raised.

invalid_arg_name

The method was passed an argument whose name falls outside the bounds of accepted or expected values. This includes very long names and names with non-alphanumeric characters other than _. If you get this error, it is typically an indication that you have made a very malformed API call.

invalid_arguments

The method was called with invalid arguments.

invalid_array_arg

The method was passed an array as an argument. Please only input valid strings.

invalid_attachments

Attachments that contain blocks are not valid

invalid_auth

Some aspect of authentication cannot be validated. Either the provided token is invalid or the request originates from an IP address disallowed from making the request.

invalid_blocks

Blocks submitted with this message are not valid

invalid_blocks_format

The blocks is not a valid JSON object or doesn't match the Block Kit syntax.

invalid_charset

The method was called via a POST request, but the charset specified in the Content-Type header was invalid. Valid charset names are: utf-8 iso-8859-1.

invalid_form_data

The method was called via a POST request with Content-Type application/x-www-form-urlencoded or multipart/form-data, but the form data was either missing or syntactically invalid.

invalid_post_type

The method was called via a POST request, but the specified Content-Type was invalid. Valid types are: application/json application/x-www-form-urlencoded multipart/form-data text/plain.

is_archived

Channel has been archived.

markdown_text_conflict

Markdown text cannot be used in conjunction with blocks or text argument.

message_limit_exceeded

Members on this team are sending too many messages. For more details, see https://slack.com/help/articles/115002422943-Usage-limits-for-free-workspaces

messages_tab_disabled

Messages tab for the app is disabled.

method_deprecated

The method has been deprecated.

missing_post_type

The method was called via a POST request and included a data payload, but the request did not include a Content-Type header.

missing_scope

The token used is not granted the specific scope permissions required to complete this request.

msg_too_long

Message text is too long

no_permission

The workspace token used in this request does not have the permissions necessary to complete the request. Make sure your app is a member of the conversation it's attempting to post a message to.

no_text

No message text provided

not_allowed_token_type

The token type used in this request is not allowed.

not_authed

No authentication token provided.

not_in_channel

Cannot post user messages to a channel they are not in.

org_login_required

The workspace is undergoing an enterprise migration and will not be available until migration is complete.

ratelimited

The request has been ratelimited. Refer to the Retry-After header for when to retry the request.

request_timeout

The method was called via a POST request, but the POST data was either missing or truncated.

restricted_action

A workspace preference prevents the authenticated user from posting.

service_unavailable

The service is temporarily unavailable

team_access_not_granted

The token used is not granted the specific workspace access required to complete this request.

team_added_to_org

The workspace associated with your request is currently undergoing migration to an Enterprise Organization. Web API and other platform operations will be intermittently unavailable until the transition is complete.

token_expired

Authentication token has expired

token_revoked

Authentication token is for a deleted user or workspace or the app has been removed when using a user token.

too_many_attachments

Too many attachments were provided with this message. A maximum of 100 attachments are allowed on a message.

two_factor_setup_required

Two factor setup is required.

user_not_in_channel

Intended recipient is not in the specified channel.