Navigating in a CSML Bot

Navigating within a flow

A flow is made of at least one step (called start), but can also contain as many steps as necessary. You should think of steps as individual, simple bits of logic, linked inside the same conversation topic (which is the flow).

To go from one step to the next, you can simply use the keyword goto (or goto step) followed by the name of the step.

To finish a flow (and close the conversation), add goto end.

start:
say "hi"
goto step otherstep // note: in the following examples, we will use the shorthand notation `goto otherstep`
otherstep:
say "I'm in otherstep"
goto end

If, at the end of a step, the goto end instruction is omitted, the conversation will be closed anyway.

In other words,goto endcan be used to exit of a conversation early at any point, but it is implicitly added at the end of all steps if no other goto instruction is present.

Navigating between flows

Similarly to navigating between steps of the same flow, you can go to the beginning of any other flow by using the goto flow keyword. This will trigger the start step of the target flow and close the current flow, so coming back to the first flow will actually go back to the beginning of that flow.

somestep:
goto flow anotherflow

Advanced navigation

Introduced in CSML v1.2

If you want to reach a specific step in a specific flow, you can use the @ notation:

This is the universal way of navigating between steps and flow. The above two methods are actually special cases of this notation:

  • When the @flow_name part is not specified, CSML interprets it as "in the current flow". So goto stepname actually is shorthand notation for goto [email protected]_flow, where current_flow is dynamically matched from the name of the current flow, and works accordingly.

  • When the step_name part is not specified, CSML interprets it as start. So as @ means "flow", goto @flow_name is the same as goto [email protected]_name which is also the same as goto flow flow_name.

Examples

goto stepname // navigate to the step named stepname in the current flow
goto flow flowname // navigate to the start step in flow flowname
goto @flowname // navigate to the start step in flow flowname
goto [email protected] // navigate to step stepname in flow flowname

Dynamic step and flow names

Introduced in CSML v1.5

As you can see above, steps and flows use strings as identifiers, but they are expressed without double quotes "...". In order to navigate to dynamically set steps or flows, CSML adds a special syntax, similar to the dereference pointer concept in other languages.

To go to a variable step or flow, you can reference the variable name prefixed with a $ sign:

do mystep = "somestep"
do myflow = "someflow"
goto [email protected]$myflow

Any of the syntaxes presented above are supported. For instance:

do buttons = [Button("Burgers"), Button("Vegetables")]
say Question(
"What is your favorite food?",
buttons = buttons
)
hold
do matched = event.match_array(buttons)
if (!matched) { /* handle case where input does not match anything */ }
do target = matched.title
goto flow $target
// depending on which button the user selected, this is equivalent to
// goto flow Burgers or goto flow Vegetables

Please note that dot notation (accessing child properties in an object or array, i.e a.b) is not supported in variable flow and step names.