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Call

A call (godoc) is the definition of an action. The values are:

Name	Type	Description
`path`	string	The path of the call. For HTTP apps, the path is appended to the app’s `RootURL`.
`expand`	Expand	A definition of the information to expand to send to the app.
`state`	Object	A set of elements to be interpreted by the app. Forms and slash commands will also populate these values.

Expand

To avoid extra communication between the app and Mattermost, you can include expansions in the calls. Expansions (godoc) will send in the call request the whole information of the required fields. You can expand each value to the following leves: “none”, “all” or “summary”.

TODO: Define differences between all and summary

The possible expansions are:

Name	Description
`app`	Expands the app information.
`acting_user`	Expands the acting user information.
`acting_user_access_token`	Include the user-level access token.
`admin_access_token`	Include the admin access token.
`channel`	Expands the channel information.
`post`	Expands the post information.
`root_post`	Expands the root post information.
`team`	Expands the team information.
`user`	Expands the subject user information.
`oauth2_app`	Expands the remote OAuth2 configuration data.
`oauth2_user`	Expands the remote OAuth2 user.

Call handling

Call Request

When a call is performed, a POST request will be made to the endpoint defined in the call. The call will include a “Mattermost-App-Authorization” header, with a jwtToken. Along the default claims, it will also send the Acting User ID.

The call request (godoc) will include:

Name	Type	Description
`values`	Object	The pairs of key values present in the call. Can be populated by forms and slash commands.
`context`	Context	The context of the call.
`raw_command`	string	The unparsed command for slash commands.
`selected_field`	string	Used in lookups and form refresh to communicate what field.
`query`	string	Used in lookups and form refresh what query strings is entered by the user.

The call type (godoc) can be:

Type	Meaning
`submit`	Submit.
`form`	Request for a form.
`cancel`	A form was canceled.
`lookup`	Lookup for dynamic selects in forms.

Call Context

Depending on the location and expansions, calls will have different context. These are all the possible context (godoc) values.

Name	Type	Description
`app_id`	string	The app ID.
`location`	Location	The location from which the call was performed.
`subject`	Subject	Event subject.
`bot_user_id`	string	Bot user ID.
`acting_user_id`	string	ID from the user performing the call.
`user_id`	string	ID from the user which is the subject of the call.
`team_id`	string	ID from the team from within which the call was performed.
`channel_id`	string	ID from the channel from within which the call was performed.
`post_id`	string	ID from the post from within which the call was performed.
`root_post_id`	string	If the call was performed from a post in a thread, the root post ID of that thread.
`mattermost_site_url`	string	Mattermost base URL.
`app_path`	string	App’s path on the Mattermost instance (appendable to `mattermost_site_url`).
`mattermost_site_url`	string	Mattermost base URL.
`user_agent`	string	User agent used to perform the call. It can be either `webapp` or `mobile`.
`bot_access_token`	string	(Expansion)
`acting_user`	User	(Expansion)
`acting_user_access_token`	string	(Expansion)
`admin_access_token`	string	(Expansion)
`oauth2`	App	(Expansion)
`app`	App	(Expansion)
`channel`	Channel	(Expansion)
`post`	Post	(Expansion)
`root_post`	Post	(Expansion)
`team`	Team	(Expansion)
`user`	User	(Expansion)

Call Response

There are several types (godoc) of responses:

Value	Description
`ok`	OK.
`error`	An error has occurred.
`form`	Should open a form.
`navigate`	Should navigate the user to a URL.

OK response

Name	Type	Description
`type`	string	Use `ok`.
`markdown`	string	(Optional) Markdown text that will be sent to the user as an ephemeral post.

Error response

Name	Type	Description
`type`	string	Use `error`.
`error`	string	Markdown text that will be sent to the user as an ephemeral post.

Form response

Name	Type	Description
`type`	string	Use `form`.
`form`	form	Form to open.

Navigate response

Name	Type	Description
`type`	string	Use `navigate`.
`navigate_to_url`	string	URL to navigate to.
`navigate_to_url`	string	URL to navigate to.

Special calls

Install

When the app is installed, a special call is made to inform the app that it has been installed on the instance. This call is used mainly to initialize any needed information. If the app asks for Permissions to act as an user, the call will include among the values, the OAuth2 client secret, under the value oauth2_client_secret. The context will include the acting user ID, the app ID, the team ID, and the app and Admin access token expanded by default.

The expected responses are either OK or Error responses.