matrix-spec/event-schemas/schema/m.room.message#m.file

{
    "type": "object",
    "title": "FileMessage",
    "description": "This message represents a generic file.",
    "allOf": [{
        "$ref": "core-event-schema/room_event.json"
    }],
    "properties": {
        "content": {
            "type": "object",
            "properties": {
                "msgtype": {
                    "type": "string",
                    "enum": ["m.file"]
                },
                "filename": {
                    "type": "string",
                    "description": "The original filename of the uploaded file."
                },
                "body": {
                    "type": "string",
                    "description": "A human-readable description of the file. This is recommended to be the filename of the original upload."
                },
                "url": {
                    "type": "string",
                    "description": "The URL to the file."
                },
                "info": {
                    "type": "object",
                    "title": "FileInfo",
                    "description": "Information about the file referred to in ``url``.",
                    "properties": {
                        "size": {
                            "type": "integer",
                            "description": "The size of the file in bytes."
                        },
                        "mimetype": {
                            "type": "string",
                            "description": "The mimetype of the file e.g. ``application/msword``."
                        }
                    }
                },
                "thumbnail_url": {
                    "type": "string",
                    "description": "The URL to the thumbnail of the file."
                },
                "thumbnail_info": {
                    "type": "object",
                    "title": "ImageInfo",
                    "description": "Metadata about the image referred to in ``thumbnail_url``.",
                    "allOf": [{
                        "$ref": "core-event-schema/msgtype_infos/image_info.json"
                    }]
                }
            },
            "required": ["msgtype", "body", "url", "filename"]
        },
        "type": {
            "type": "string",
            "enum": ["m.room.message"]
        }
    }
}