Conditions

You can carry out conditional logic in scenes using values from the Data model objects. The following sections describe the valid syntax for conditions.

Logical operators

Operator	Description
`&&`	Logical AND. Inner expressions are evaluated iteratively, and the evaluation is short-circuited if any expression evaluates to false.
`\|\|`	Logical OR. Inner expressions are evaluated iteratively, and the evaluation is short-circuited if any expression evaluates to true
`!`	Logical NOT. The evaluation of the inner expression is negated

Numerical and string operators

The following numerical and string operators are supported:

Operator	Description
`+`	Add numbers or string concatenation
`-`	Subtract numbers
*``**	Multiply numbers
`/`	Divide numbers

Booleans

The following constant booleans are supported:

Constant	Description
`true`	Must be lowercase
`false`	Must be lowercase
`!false`	Evaluates to `true`. Must be lowercase.

Comparison operators

The following comparison operators are provided:

Operator	Description
`==`	Equals
`!=`	Not equals
`<`	Less than
`<=`	Less than equals
`>`	Greater than
`>=`	Greater than equals

Lists and maps

Given a list named session.params.myList:

Syntax	Description
`x in session.params.myList`	Returns true if the value `x` is in `session.params.myList`
`myList[x]`	Returns the value at index `x` of `myList`
`size(session.params.myList)`	Returns the size of a list

Given a map named session.params.myMap:

Syntax	Description
`session.params.myMap == {"one": 1, "two":2}`	Returns `true` if maps are equal
`session['params']['myMap']['one']`	Returns the value with specified key
`size(session.params.myMap)`	Returns the map size

Data model

The following objects can be used within scene conditions:

Syntax	Description
`intent`	Matched intent parameter data
`scene`	Slot-filling data
`session`	Session storage data
`user`	User storage data
`home`	Home storage data
`device`	Device capability and location data
`canvas`	Canvas state data
`resources`	Localized project resources (audio, images, strings, etc.) data

The following is an example snippet of the full data model in JSON:

{
  "intent": {
    "params": {
      "<param_name>": {
        "original": "five people",
        "resolved": 5
      }
    }
   },
  "session": {
    "params": {
      "<session_params_key>": "<session_params_value>"
    }
  },
  "scene": {
    "slots": {
      "status": "FINAL",
      "params": {
        "<slot_name>": "<slot_value>"
      }
    }
  },
  "user": {
    "params": {
      "<user_params_key>": "<user_params_value>"
    },
    "permissions": [
      "DEVICE_PRECISE_LOCATION"
    ],
    "accountLinkingStatus": "LINKED",
    "verificationStatus": "VERIFIED",
    "lastSeenTime": {
      "seconds": 123,
      "nanos": 456
    },
    "engagement": {
      "pushNotificationIntents": [
        "intent1",
        "intent2"
      ]
    }
  },
  "home": {
    "params": {
      "<home_params_key>": "<home_params_value>"
    }
  },
  "canvas": {
    "state": {
      "<canvas_state_key>": "<canvas_state_value>"
    }
  },
  "device": {
    "capabilities": [
      "SPEECH",
      "RICH_RESPONSE",
      "LONG_FORM_AUDIO",
      "INTERACTIVE_CANVAS"
    ],
    "currentLocation": {
      "coordinates": {
        "latitude": 37.422,
        "longitude": -122.084
      },
      "postalAddress": {
        "revision": 0,
        "regionCode": "US",
        "languageCode": "en",
        "postalCode": "94043",
        "sortingCode": "",
        "administrativeArea": "California",
        "locality": "Mountain View",
        "sublocality": "",
        "addressLines": ["1600 Amphitheatre Parkway"],
        "recipients": [],
        "organization": ""
      }
    }
  },
  "resources": {
    "strings": {
      "<resource_string_key>": "<resource_string_value>"
    },
    "images": {
      "<resource_image_key>": "<resource_image_value>"
    }
  }
}

Usage reference

The following syntax examples assumes you are working with session.params object:

session.params = {
  "flag": true,
  "count": 10,
  "name": "john smith",
  "myList": [1, 2, 3],
  "myMap": {"one": 1, "two":2}
}

You can carry out the following conditional operations:

// numbers and boolean logic
session.params.count > 0 && session.params.count < 100    // AND
session.params.count == 0 || session.params.count != 5    // OR
!(session.params.count <= 0)         // NOT

// booleans
!false                      // true constant
session.params.flag         // boolean variable
session.params.flag == true // explicitly compare with true constant

// strings
session.params.name == "john smith"  // double quotes supported
session.params.name == 'john smith'  // single quotes supported
session.params.name.contains("john") // substring
session.params.name + "!!!" == "john smith!!!" // string concatenation
session.params.name < "abc"          // compares lexicographically
size(session.params.name) == 10      // length of string

// lists
1 in session.params.myList        // "contains in list" operator
session.params.myList[0] == 1     // "index into list" operator
size(session.params.myList) == 3  // returns number of elements in the list

// maps
session.params.myMap == {"one": 1, "two":2} // compare map with json
session['params']['myMap']['one'] == 1      // index using square brackets
size(session.params.myMap) == 2             // number of entries in the map