You can carry out conditional logic in scenes using values from the
session.params
, user.params
, intent.params
and scene.slots.params
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 |
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