Scalar-function rule

Introduction

Casewhere rule is not only about boolean predicates. You can use rule to implement a scalar function that does some logic and returns a value. It is always a good practice to extract computing logic in workflows into rules that can be reused in different places.

Rule syntax

Keywords

You can use the following keywords to work with scalar-function rules:

Name	Type	Description
@users	DslUser	The user object in context. Read access rule for more information.
@parameters	DynamicDataObject	You can access attributes using the “dot” operator. For example, “@parameters.address”.
@apiFactory	IManagedApiFactory	To construct Casewhere API objects. Read here for the full list of available Apis.

Examples

Example 1

Assuming you have a rule "Convert Meter To Centimeter" that converts centimeter to meter:

@parameters.meterValue * 100

You can evaluate the rule in a workflow scripted activity using RuleApi:

var ruleApi = ctx.Use<IRuleApi>();
 
var parameters = new Dictionary<string, object>();
parameters["meterValue"] = 1;
 
var cm = ruleApi.Eval<int>("Convert Meter To Centimeter", parameters);

Example 2

Assuming you need to implement a function to query products by SKU and you want to reuse it in many places. You can create a rule "Find Products By SKU" like below:

#predicate 
 
var dataApi = @apiFactory.Get<IDataApi>();
var filter = FilterBuilder.Create().Eq("SKU", @parameters.SKU).Build();
var result = dataApi.Search(DataObjectApiQuery
    .For("Product")
    .FilterBy(filter));
 
return result.Data;

You can evaluate the rule in a workflow scripted activity using RuleApi:

var ruleApi = ctx.Use<IRuleApi>();

var parameters = new Dictionary<string, object>();
parameters["SKU"] = "LAPTOP";
 
var products = ruleApi.Eval<List<DynamicDataObject>>("Find Products By SKU", parameters);