Creating a form flow definition

A form flow definition is a JSON document that defines steps and which steps can be reached under what conditions when the current step is completed. Each step can have zero or more actions (e.g. retrieve external data) that trigger when the task is opened or completed. Depending on the type of step, the step can be handled in a different way. The way a form is handled can differ from a payment, for example.

For information on how to link a form flow definition to a task, see here.

Definitions

To create form flow definition, the following steps are necessary:

• Create a form flow .json file under the following path: */resources/config/form-flow/.

• Add each individual step to the form flow definition, e.g.:

{
    "startStep": "personalDetailsStep",
    "steps": [
        {
            "key": "personalDetailsStep"
        },
        {
            "key": "loanApprovedStep"
        },
        {
            "key": "loanDeniedStep"
        },
        {
            "key": "summaryStep"
        }
    ]
}

• Add the next steps for each of the individual steps. This can be done through the nextStep property, which supports a single step, or nextSteps, which supports multiple next steps. Each step should correspond to the key of another step defined in this form flow.

{
    "startStep": "personalDetailsStep",
    "steps": [
        {
            "key": "personalDetailsStep",
            "nextSteps": [
                {
                    "step": "loanApprovedStep"
                },
                {
                    "step": "loanDeniedStep"
                }
           ]
        },
        {
            "key": "loanApprovedStep",
            "nextStep": "summaryStep"
        },
        {
            "key": "loanDeniedStep",
            "nextStep": "summaryStep"
        },
        {
            "key": "summaryStep"
        }
    ]
}

• The personalDetailsStep is now followed by two other steps. This is only allowed when at least one of the two steps is conditional. The order of next step matters. The first nextStep with condition that is evaluated to true will be the next step. When all the conditions are evaluated to false the next step will be the default step; which is the step without condition. If no next step is found, the form flow will end. The expression inside the condition is further explained here.

{
    "startStep": "personalDetailsStep",
    "steps": [
        {
            "key": "personalDetailsStep",
            "nextSteps": [
                {
                    "step": "loanApprovedStep",
                    "condition": "${step.submissionData.personalDetails.age >= 21}"
                },
                {
                    "step": "loanDeniedStep"
                }
           ]
        },
        {
            "key": "loanApprovedStep",
            "nextStep": "summaryStep"
        },
        {
            "key": "loanDeniedStep",
            "nextStep": "summaryStep"
        },
        {
            "key": "summaryStep"
        }
    ]
}

• Configure the step type. Currently, the only step type supported is form, which requires a definition property to be set. This refers to the key of the form. For more information on step types, see here

  Which properties are required to be set depends on the step type.

{
    "startStep": "personalDetailsStep",
    "steps": [
        {
            "key": "personalDetailsStep",
            "type": {
                "name": "form",
                "properties": {
                    "definition": "personal-details-form"
                }
            },
            "nextSteps": [
                {
                    "step": "loanApprovedStep",
                    "condition": "${step.submissionData.personalDetails.age >= 21}"
                },
                {
                    "step": "loanDeniedStep"
                }
           ]
        },
        {
            "key": "loanApprovedStep",
            "type": {
                "name": "form",
                "properties":  {
                    "definition": "loan-approved-form"
                }
            },
            "nextStep": "summaryStep"
        },
        {
            "key": "loanDeniedStep",
            "type": {
                "name": "form",
                "properties":  {
                    "definition": "loan-denied-form"
                }
            },
            "nextStep": "summaryStep"
        },
        {
            "key": "summaryStep",
            "type": {
                "name": "form",
                "properties":  {
                    "definition": "summary-form"
                }
            }
        }
    ]
}

• Add triggers to steps where necessary (e.g. to store data externally). See below for more information.

Expressions

Form flow supports Spring Expression Language (SpEL) expressions to allow for more complex actions when a step is opened or completed. Expressions can be recognized by the surrounding ${ } characters. The following additional properties are supported for steps:

• onBack. Triggers the expressions when navigating to the previous step, e.g. to remove data from a document.

• onOpen. Triggers the expressions when the step is opened, e.g. to retrieve external data.

• onComplete. Triggers the expressions when the step is complete, e.g. to store the results in a document.

Each of these properties supports more than one expression, e.g. when a step is opened, external data from more than one source is retrieved. These expressions are evaluated in order.

Valtimo provides access to certain variables in the SpEL context, e.g. what the current step is. Which properties are available can be found here

{
    "startStep": "personalDetailsStep",
    "steps": [
        {
            "key": "personalDetailsStep",
            "type": {
                "name": "form",
                "properties": {
                    "definition": "personal-details-form"
                }
            },
            "onOpen": ["${someService.retrieveData(additionalProperties)}"],
            "nextSteps": [
                {
                    "step": "loanApprovedStep",
                    "condition": "${step.submissionData.personalDetails.age >= 21}"
                },
                {
                    "step": "loanDeniedStep"
                }
            ]
        },
        {
            "key": "loanApprovedStep",
            "type": {
                "name": "form",
                "properties": {
                    "definition": "loan-approved-form"
                }
            },
            "onBack": ["${someService.removeData(additionalProperties)}"],
            "nextStep": "summaryStep"
        },
        {
            "key": "loanDeniedStep",
            "type": {
                "name": "form",
                "properties": {
                    "definition": "loan-denied-form"
                }
            },
            "nextStep": "summaryStep"
        },
        {
            "key": "summaryStep",
            "onComplete": ["${valtimoFormFlow.completeTask(additionalProperties, step.submissionData)}"],
            "type": {
                "name": "form",
                "properties": {
                    "definition": "summary-form"
                }
            }
        }
    ]
}

By default, SpEL allows access to every Spring bean from inside expressions. For security reasons, this has been changed to a whitelist instead. More information on how to whitelist Spring beans is available here and more information on SpEL can be found here.