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Forms

Mattermost Apps use a single data structure for user input: the Form. A form gets input from a modal dialog or from slash command arguments. Forms in a modal dialog open on the user interface as a result of a call response.

Data structure

The structure of a form (godoc) is defined in the following table:

Name	Type	Description
`title`	string	Title of the form, shown in modal dialogs.
`submit`	Call	Call to perform when the form is submitted or the slash command is executed.
`fields`	Fields	List of fields in the form.
`source`	Call	Call to perform when a form’s fields are not defined or when the form needs to be refreshed.
`header`	string	Text used as introduction in modal dialogs.
`footer`	string	Text used at the end of modal dialogs.
`icon`	string	Either a fully-qualified URL, or a path for an app’s static asset.
`submit_buttons`	string	Name of the form field to be used as the list of submit buttons. Must be a `static_select` or `dynamic_select` field. Default value is a single button: `OK`.

Fields

The structure of a form field (godoc) is defined in the following table:

Name	Type	Description
`name`	string	Key to use in the values field of the call. Cannot include spaces or tabs.
`type`	FieldType (string)	The type of the field.
`is_required`	bool	Whether the field has a mandatory value.
`readonly`	bool	Whether a field’s value is read-only.
`value`	any	The field’s default value.
`description`	string	Short description of the field, displayed beneath the field in modal dialogs.
`label`	string	The label of the flag parameter; used with autocomplete. Ignored for positional parameters.
`hint`	string	The hint text for the field; used with autocomplete.
`position`	int	The index of the positional argument. A value greater than zero indicates the position this field is in. A value of `-1` indicates the last argument.
`multiselect`	bool	Whether a select field allows multiple values to be selected.
`modal_label`	string	Label of the field in modal dialogs. Defaults to `label` if not defined.
`refresh`	bool	Allows the form to be refreshed when the value of the field has changed.
`options`	SelectOption	A list of options for static select fields.
`lookup`	Call	A call that returns a list of options for dynamic select fields.
`subtype`	TextFieldSubtype (string)	The subtype of `text` field that will be shown.
`min_length`	int	The minimum length of `text` field input.
`max_length`	int	The maximum length of `text` field input.

Field types

The types of form fields are:

Name	Description
`text`	A plain text field.
`static_select`	A dropdown select with static elements.
`dynamic_select`	A dropdown select that loads the elements dynamically.
`bool`	A boolean selector represented as a checkbox.
`user`	A dropdown to select users.
`channel`	A dropdown to select channels.
`markdown`	An arbitrary markdown text; only visible in modal dialogs. Read-only.

Text fields

Text field subtypes

The text field subtypes, except textarea, map to the types of the HTML input form element. The available subtypes are listed in the following table:

Subtype Name	Description
input	A single-line text input field.
textarea	A multi-line text input field; uses the HTML `textarea` element.
email	A field for editing an email address.
number	A field for entering a number; includes a spinner component.
password	A single-line text input field whose value is obscured.
tel	A field for entering a telephone number.
url	A field for entering a URL.

Select fields

Select options

The data structure of an option (SelectOption) in a select field is defined by the following table:

Name	Type	Description
`label`	string	User-facing string. Defaults to `value` and must be unique on this field.
`value`	string	Machine-facing value. Must be unique on this field.
`icon_data`	string	Either a fully-qualified URL, or a path for an app’s static asset.

Dynamic select options

A dynamic select field gets its options by performing the lookup call. The call response is expected to contain the list of select field options in the items key of the data map. Each option is of the type SelectOption.

Example lookup call response:

{
    "type": "ok",
    "data": {
        "items": [
            {
                "label": "Option One",
                "value": "option_1"
            },
            {
                "label": "Option Two",
                "value": "option_2"
            }
        ]
    }
}

Select field refresh

If the refresh value is set to true, the form’s source call is performed any time the field’s value changes. The call request will include the current values of the form. The call response is expected to contain a full, updated form definition.

Markdown fields

Markdown fields are a special field that allows you to better format your form. They will not generate any value in the form submission sent to the App. The content is defined in the description property of the field.

Form submission

When the form is submitted, either by executing a slash command or clicking a submit button, the form’s submit call is performed.

Slash command arguments

Slash command arguments and flags are defined by form fields. When a slash command is typed, the command arguments are retrieved from the command’s form. If a form was not included with the command binding, the binding’s call will be invoked to provide a form response.

Example form with flag arguments

Example form with positional

command-flags-example_header"> class="collapseToggle icon-chevron-right" role="img" title="Expand / collapse" aria-label="Expand / collapse" onclick="doToggle('slash-command-flags-example_body','slash-command-flags-example_toggle')"> span> -command-flags-example_header" id="slash-command-flags-example_body"> tabindex="0" style="background-color:#f0f3f3;-moz-tab-size:4;-o-tab-size:4;tab-size:4;">

{ "location": "sub", "label": "sub", "description": "Subscribe to an event", "form": { "title": "Subscribe to an event", "header": "Subscribe to a Mattermost Server event", "icon": "icon.png", "fields": [ { "name": "eventname", "label": "eventname", "type": "text", "subtype": "input", "description": "The name of the event to subscribe to", "is_required": true }, { "name": "teamid", "label": "teamid", "type": "text", "subtype": "input", "description": "The ID of the team" }, { "name": "channelid", "label": "channelid", "type": "text", "subtype": "input", "description": "The ID of the channel" } ], "submit": { "path": "/sub", } } } command-positional-example_header"> class="collapseToggle icon-chevron-right" role="img" title="Expand / collapse" aria-label="Expand / collapse" onclick="doToggle('slash-command-positional-example_body','slash-command-positional-example_toggle')"> arguments -command-positional-example_header" id="slash-command-positional-example_body"> tabindex="0" style="background-color:#f0f3f3;-moz-tab-size:4;-o-tab-size:4;tab-size:4;">{ "location": "sub", "label": "sub", "description": "Subscribe to an event", "form": { "title": "Subscribe to an event", "header": "Subscribe to a Mattermost Server event", "icon": "icon.png", "fields": [ { "name": "eventname", "label": "eventname", "type": "text", "subtype": "input", "description": "The name of the event to subscribe to", "is_required": true, "position": 1 }, { "name": "teamid", "label": "teamid", "type": "text", "subtype": "input", "description": "The ID of the team", "position": 2 }, { "name": "channelid", "label": "channelid", "type": "text", "subtype": "input", "description": "The ID of the channel", "position": 3 } ], "submit": { "path": "/sub", } } }
During autocomplete, the user can open the form in a modal dialog to finish entering command arguments.
Any fields not supported by commands, such as markdown fields, or form attributes not visible in commands, such as the title, will be shown when the form is opened as a modal dialog.


When the slash command is executed, the form’s submit call will be performed.
End-to-end examples  
Click a button in the channel header  

    
        
        MM submit request
    
    
        
            POST /send HTTP/1.1
Content-Type: application/json

{
    "path": "/send",
    "expand": {},
    "context": {
        "app_id": "hello-world",
        "location": "/channel_header/send-button",
        "user_agent": "webapp",
        "track_as_submit": true,
        "mattermost_site_url": "http://mattermost:8066",
        "developer_mode": true,
        "app_path": "/plugins/com.mattermost.apps/apps/hello-world",
        "bot_user_id": "mgbd1czngjbbdx6eqruqabdeie",
        "bot_access_token": "fpbrjjnp5if59fazjjn794f3zy",
        "acting_user": {
            "id": "7q7kaakokfdsdycy3pr9ctkc5r"
            // additional fields omitted for brevity
        },
        "oauth2": {}
    }
}

        
    



    
        
        App form response
    
    
        
            {
    "type": "form",
    "form": {
        "title": "Hello, world!",
        "icon": "icon.png",
        "fields": [
            {
                "type": "text",
                "name": "message",
                "label": "Message"
            },
            {
                "type": "user",
                "name": "user",
                "label": "User"
            },
            {
                "type": "static_select",
                "name": "option",
                "label": "Option",
                "options": [
                    {
                        "label": "Option One",
                        "value": "option_1"
                    },
                    {
                        "label": "Option Two",
                        "value": "option_2"
                    }
                ]
            }
        ],
        "call": {
            "path": "/send"
        }
    }
}


        
    


Select from a user field in a modal dialog  

    
        
        MM form request
    
    
        
            POST /send-form-source HTTP/1.1
Content-Type: application/json

{
    "path": "/send-form-source",
    "expand": {},
    "values": {
        "message": null,
        "option": null,
        "user": {
            "label": "hello-world",
            "value": "mgbd1czngjbbdx6eqruqabdeie"
        }
    },
    "context": {
        "app_id": "hello-world",
        "location": "/channel_header/send-button",
        "user_agent": "webapp",
        "mattermost_site_url": "http://localhost:8066",
        "developer_mode": true,
        "app_path": "/plugins/com.mattermost.apps/apps/hello-world",
        "bot_user_id": "mgbd1czngjbbdx6eqruqabdeie",
        "bot_access_token": "omppotxyt3ddbdczsjddzxuqro",
        "acting_user": {
            "id": "7q7kaakokfdsdycy3pr9ctkc5r"
            // additional fields omitted for brevity
        },
        "oauth2": {}
    },
    "selected_field": "user"
}

        
    



    
        
        App form response
    
    
        
            {
    "type": "form",
    "form": {
        "source": {
            "path": "/send-form-source"
        },
        "title": "Hello, world!",
        "icon": "icon.png",
        "submit": {
            "path": "/modal-submit"
        },
        "fields": [
            {
                "name": "message",
                "type": "text",
                "label": "Message"
            },
            {
                "name": "user",
                "type": "user",
                "value": {
                    "label": "hello-world",
                    "value": "mgbd1czngjbbdx6eqruqabdeie"
                },
                "label": "User",
                "refresh": true
            },
            {
                "name": "option",
                "type": "static_select",
                "label": "Option",
                "options": [
                    {
                        "label": "Option One",
                        "value": "option_1"
                    },
                    {
                        "label": "Option Two",
                        "value": "option_2"
                    }
                ]
            }
        ]
    }
}

    
        Note:

        "refresh": true is used to tell the client to notify the server when a value is selected from this field
    


        
    


Dynamic select field lookup  

    
        
        Initial form response
    
    
        
            POST /send-dynamic-form HTTP/1.1
Content-Type: application/json

{
    "type": "form",
    "form": {
        "title": "Dynamic field test",
        "icon": "icon-info.png",
        "submit": {
            "path": "/dynamic-form-submit"
        },
        "fields": [
            {
                "name": "option",
                "type": "dynamic_select",
                "label": "Option",
                "lookup": {
                    "path": "/dynamic-form-lookup"
                }
            }
        ]
    }
}

        
    



    
        
        MM lookup request
    
    
        
            POST /dynamic-form-lookup HTTP/1.1
Content-Type: application/json

{
    "path": "/dynamic-form-lookup",
    "expand": {},
    "values": {
        "option": null
    },
    "context": {
        "app_id": "hello-world",
        "location": "/channel_header/info-button",
        "user_agent": "webapp",
        "mattermost_site_url": "http://localhost:8066",
        "developer_mode": true,
        "app_path": "/plugins/com.mattermost.apps/apps/hello-world",
        "bot_user_id": "mgbd1czngjbbdx6eqruqabdeie",
        "bot_access_token": "fqez47d1jtnbzcty3xnydjoq6h",
        "acting_user": {
            "id": "7q7kaakokfdsdycy3pr9ctkc5r"
            // additional fields omitted for brevity
        },
        "oauth2": {}
    },
    "selected_field": "option"
}

        
    



    
        
        App lookup response
    
    
        
            {
    "type": "ok",
    "data": {
        "items": [
            {
                "label": "Option One",
                "value": "option_1"
            },
            {
                "label": "Option Two",
                "value": "option_2"
            }
        ]
    }
}

        
    


Submit from a modal dialog  

    
        
        Initial form response
    
    
        
            {
    "type": "form",
    "form": {
        "source": {
            "path": "/send-form-source"
        },
        "title": "Hello, world!",
        "icon": "icon.png",
        "submit": {
            "path": "/modal-submit"
        },
        "fields": [
            {
                "name": "message",
                "type": "text",
                "label": "Message"
            },
            {
                "name": "user",
                "type": "user",
                "label": "User",
                "refresh": true
            },
            {
                "name": "option",
                "type": "static_select",
                "label": "Option",
                "options": [
                    {
                        "label": "Option One",
                        "value": "option_1"
                    },
                    {
                        "label": "Option Two",
                        "value": "option_2"
                    }
                ]
            }
        ]
    }
}

        
    



    
        
        MM submit request
    
    
        
            POST /modal-submit HTTP/1.1
Content-Type: application/json

{
    "path": "/modal-submit",
    "expand": {},
    "values": {
        "message": "hello!",
        "option": {
            "label": "Option Two",
            "value": "option_2"
        },
        "user": {
            "label": "hello-world",
            "value": "mgbd1czngjbbdx6eqruqabdeie"
        }
    },
    "context": {
        "app_id": "hello-world",
        "location": "/channel_header/send-button",
        "user_agent": "webapp",
        "track_as_submit": true,
        "mattermost_site_url": "http://localhost:8066",
        "developer_mode": true,
        "app_path": "/plugins/com.mattermost.apps/apps/hello-world",
        "bot_user_id": "mgbd1czngjbbdx6eqruqabdeie",
        "bot_access_token": "gqouzbhrb3rw9n9qr43nykyuoy",
        "acting_user": {
            "id": "7q7kaakokfdsdycy3pr9ctkc5r"
           // additional fields omitted for brevity
        },
        "oauth2": {}
    }
}

        
    



    
        
        App submit response
    
    
        
            {
    "type": "ok",
    "text": "## Form values\n- message: \"hello!\"\n- option: {\"label\":\"Option Two\", \"value\":\"option_2\"}\n- user: {\"label\":\"hello-world\", \"value\":\"mgbd1czngjbbdx6eqruqabdeie\"}\n"
}

        
    


Example error responses  
Single error  
{
    "type": "error",
    "text": "This is the error."
}
Errors for specific fields  
{
    "type": "error",
    "data": {
        "errors": {
            "field_name": "This field seems to have an invalid value."
        }
    }
}
A root error and specific field errors  
{
    "type": "error",
    "text": "This is the root error.",
    "data": {
        "errors": {
            "field_name": "This field seems to have an invalid value."
        }
    }
}

Forms

Data structure

Fields

Field types

Text fields

Text field subtypes

Select fields

Select options

Dynamic select options

Select field refresh

Markdown fields

Form submission

Slash command arguments

End-to-end examples

Click a button in the channel header

Select from a user field in a modal dialog

Dynamic select field lookup

Submit from a modal dialog

Example error responses

Single error

Errors for specific fields

A root error and specific field errors

Tell us more