Rules are probably best described by using examples. This chapter contains numerous real world samples.

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You have a form with three controls and you have assigned them Names N1, N2 and T respectively. When the user enters a value in either N1 or N2 you want to set the value of T to the sum of N1 and N2. The rule would be written as

T.value = N1.value + N2.value;

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Show/Hide Manager Approval

You have a flow and the first form has a Section for manager approval. The Section is hidden by default. Here is an example of a rule that makes the section visible in the second step of the flow which is a linked activity assigned to the manager role. 

if (form.load) {
  var an = _data.getParameter ("flow.activity.name");
  if (an === 'Manager'){
    ManagerApproval.visible = true;
  } else {
    ManagerApproval.visible = false;
  }
}

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The 1st rule "Load Products" populates both the visible and hidden dropdowns with options from a database.

/*member descriptionproductCode, productIdproductName, resultSet */
var x;
  
if (form.load) {
  eval('x=' + http.get('httphttps://localhost:8082app.frevvo.com/database/BIRT/productsallProducts'));   
  
    var opts1 = [];
     var opts2 = [];
  
    for (var i=0; i < x.resultSet.length; i++) { 
        if (x.resultSet[i]) {
             opts1[i] = x.resultSet[i].descriptionproductName;
             opts2[i] = x.resultSet[i].productIdproductCode;
        }
    }
 
    Products.options = opts1;
  PID.options = opts2;
  Products.value = opts1[0]; // default to 1st product option
  PID.value = opts2[0];

}

Finding a Selected Options Index

The 2nd rule Select Product ID keeps the hidden PID dropdown syncronized synchronized with the visible Products dropdown.

}
if (Products.value.length > 0)

{
     var i;
     for (var x in Products.options) {
        if ((Products.value + '=' + Products.value) === Products.options[x]){
             i = Products.options.indexOf(Products.options[x]);
        }
    }
 
  PID.value = PID.options[i] + ''.split('=')[0];

}

In v4 rules using hidden dropdowns to keep descriptive option labels visible to the user while keeping cryptic database values hidden are often no longer necessary. Dropdown options have values distinct from the human visible option labels. The above can now be achieved with a single simpler rule:

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You can style this form so the comment input controls align with the checkbox options. See details and download a working sample form here. 

var heartProblem = false;
var foodAllergy = false;
var rashes = false;
var jointInjury = false;
var asthma = false;
var moodiness = false;

for (var i = 0; i < MedicalIssues.value.length; i++)
{
  if (MedicalIssues[i].value === 'heart_problem') {
    heartProblem = true;
  } else if (MedicalIssues[i].value === 'food_allergy') {
    foodAllergy = true;
  } else if (MedicalIssues[i].value === 'rashes') {
    rashes = true;
  } else if (MedicalIssues[i].value === 'joint_injury') {
    jointInjury = true;
  } else if (MedicalIssues[i].value === 'asthma') {
    asthma = true;
  } else if (MedicalIssues[i].value === 'moodiness') {
    moodiness = true;
  }
}

if (heartProblem === true) {
  heartProblemDetails.visible = true;
  heartProblemDetails.required = true;
} else {
  heartProblemDetails.visible = false;
  heartProblemDetails.required = false;
  //heartProblemDetails.value = null;
}

if (foodAllergy === true) {
  foodAllergyDetails.visible = true;
  foodAllergyDetails.required = true;
} else {
  foodAllergyDetails.visible = false;
  foodAllergyDetails.required = false;
  //foodAllergyDetails.value = null;
}

if (rashes === true) {
  rashesDetails.visible = true;
  rashesDetails.required = true;
} else {
  rashesDetails.visible = false;
  rashesDetails.required = false;
  //rashesDetails.value = null;
}

if (jointInjury === true) {
  jointInjuryDetails.visible = true;
  jointInjuryDetails.required = true;
} else {
  jointInjuryDetails.visible = false;
  jointInjuryDetails.required = false;
  //jointInjuryDetails.value = null;
}

if (asthma === true) {
  asthmaDetails.visible = true;
  asthmaDetails.required = true;
} else {
  asthmaDetails.visible = false;
  asthmaDetails.required = false;
  //asthmaDetails.value = null;
}

if (moodiness === true) {
  moodinessDetails.visible = true;
  moodinessDetails.required = true;
} else {
  moodinessDetails.visible = false;
  moodinessDetails.required = false;
  //moodinessDetails.value = null;
}

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/ Calculate Hospital Stay Duration 
if (A.value !== '' && D.value !== '') { 
    var da = A.value.split('-'); 
    var Ams = new Date(da[0],da[1],da[2]); 
    da = D.value.split('-'); 
    var Dms = new Date(da[0],da[1],da[2]);
 
    if (Ams > Dms) { 
        Days.value = 'Discharge date must be after Admission Date'; 
    } else { 
        Days.value = (Dms - Ams) / (1000*60*60*24) + ' days'; 
    } 
}

Duration (between Date/Time)

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Traveler1.visible = false;
Traveler2.visible = false;
Traveler3.visible = false;
Traveler1.required = false;
Traveler2.required = false;
Traveler3.required = false;

for (var i=0; i < NumTickets.value; i++) {
 if (i >= 0) {
  Traveler1.visible = true;
  Traveler1.required = true;
 }
 if (i >= 1) {
  Traveler2.visible = true;
  Traveler2.required = true;
 }
 if (i >= 2) {
  Traveler3.visible = true;
  Traveler3.required = true;
 }
}

Tables

Tables are identical to repeat controls when referenced in business rules. Tables are a grid layout of repeating items. All the rule examples in this chapter that discuss repeats apply also to tables. The one important note is that you cannot explicitly name the repeat control inside your table. The repeat control inside a table is automatically named as <TableName>Repeat. For example a table named Expense automatically has a repeat named ExpenseRepeat. The rule ExpenseRepeat.itemAdded and ExpenseRepeat.itemIndex references an item added to your table and that item's index respectively.

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Let's take a look at a simple example. Users are instructed to enter a capital Y in a table if they are planning on calling a customer. The user enters the "Y" then tabs to the company name column. The minus icon for that row will disappear.  

In this example, the name of the table control is CustomerTable and column 0 in the table is named ContactCustomer.

Here is the rule:

for (var i=0; i<ContactCustomer.value.length; i++) {
    if (ContactCustomer[i].value === "Y") {
        CustomerTableItem[i].deletable = false;
    } else {
        CustomerTableItem[i].deletable = true;
    }
}

Notice the TableItem deletable property is set to false when a capital Y is entered in the first column. This will remove the minus icon for that row of the table. The for loop cycles through the table rows until the Max# property is reached. 

form.load

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Clearing Values in a Table

This rule clears the values from all rows in a table. Notice the For loop that iterates over all the rows. Inside the loop a null value is assigned to all the columns in the table row.

 for (var i = 0; i < Col0.value.length; i++) { 
    Col0[i].value = null;
    Col1[i].value = null;
    Col2[i].value = null;
  } 

You cannot clear an entire table from a rule.

form.load

Rules can be used to initialize field values. This is a very useful feature and is often used to dynamically populate dropdown options from a database. Rules using form.load are triggered when a form first loads and when a workflow is loaded from a task list.

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A rule can dynamically display an image uploaded to your form via the upload control. In this example the upload control is named 'u'. The form also must contain a message control as a place holder for displaying the uploaded image. The rule dynamically creates a URL to the uploaded image in the temporary attachment repository. The upload control's value 'u.value' is a GUID that uniquely identifies the attachment. The uploaded image will be included in the submissions pdf.

if (u.value.length > 0) {
  var baseUrl = _data.getParameter('_frevvo_base_url') + 
      ""/frevvo/web/tn/" +
      _data.getParameter('tn.id') +
      "/user/"+_data.getParameter('user.id') +
      "/app/"+_data.getParameter('app.id') +
      "/form/"+_data.getParameter('form.id');
 
  im.value = "'<img src="'" +
         baseUrl + "'/attachment/"' + u.value+"'/does_not_matter'"/>"';
} 

Here is the example form before and after the user has upload the orangegrovefrevvo.logo,orange.png image:

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