FlowOn Expression Language

The FlowOn Expression Language is a comprehensive library of functions and operators used to write expressions in FlowOn Logic. Expressions are used throughout FlowOn Logic constructs—in Formulas, Decision Tables, Decision Trees, Validations, Flow steps, and anywhere calculations, comparisons, or transformations are needed.

Function Categories

The Expression Language provides 85 built-in functions organized into categories:

Category	Count	Purpose	Documentation
String Functions	14	Text manipulation and formatting	Concatenate, Format, Replace, Substring
Math Functions	9	Arithmetic operations and calculations	Add, Subtract, Multiply, Divide
Date Functions	23	Date/time manipulation and calculations	Now, Add Days, Days Diff
Logical Operators	2	Combining boolean expressions	And, Or
Comparison Operators	14	Comparing values	Equals, Greater Than, Contains
Null Check Operators	7	Testing for null and empty values	Null, Not Null, Any
Collection Functions	5	Aggregate operations on lists	Count, Sum, Average, Max, Min
Control Functions	1	Conditional expressions	If Condition
Constants	9	Literal values of specific types	String, Integer, Money
Logic Block Functions	1	Execute reusable logic blocks	Run Logic Block

Type System

The Expression Language uses the Dynamics 365 type system. Understanding types is essential for writing correct expressions.

Supported Types

Type	Description	Example Values
string	Text value	"Hello", "Order-12345"
integer	Whole number	42, -100, 0
decimal	Precise decimal number	3.14159, 0.001
float	Floating-point number	2.71828, 1.5e10
money	Currency value	$1,500.00, €2,340.50
boolean	True or false	true, false
date / datetime	Date and time	2026-01-15T14:30:00Z
entityReference	Reference to a record	Lookup to Account, Contact, etc.
optionSet	Choice from a list	Status: Active, Inactive
list	Collection of values	List of integers, list of strings

Type Promotion

When mixing numeric types in calculations, the result type is promoted to the "highest weight" type:

Type Weight Order (lowest to highest): integer → float → decimal → money

For example:

• integer + integer → integer
• integer + decimal → decimal
• float + money → money

Quick Reference

String Functions

Function	Description
Concatenate	Join strings together
Format	Replace placeholders with values
Replace	Replace substring occurrences
Substring	Extract part of a string
To Lower Case	Convert to lowercase
To Upper Case	Convert to uppercase
Trim	Remove leading/trailing whitespace
Index Of	Find first position of substring
Last Index Of	Find last position of substring
String Length	Get character count
Match Pattern	Test against regex pattern
To String	Convert to formatted string
Configuration Value	Get configuration variable
Localized Resource	Get localized string

Math Functions

Function	Description
Add	Sum values
Subtract	Subtract values
Multiply	Multiply values
Divide	Divide values
Modulo	Get remainder
Raise to Power	Exponentiation
Max Value	Get largest value
Min Value	Get smallest value
Random	Generate random integer

Date Functions

Function	Description
Now	Current timestamp
Day	Extract day component
Month	Extract month component
Year	Extract year component
Day Of Week	Get day of week (0-6)
Add Days	Add/subtract days
Add Hours	Add/subtract hours
Add Minutes	Add/subtract minutes
Add Seconds	Add/subtract seconds
Add Month	Add/subtract months
Add Years	Add/subtract years
Days Diff	Difference in days
Hours Diff	Difference in hours
Minutes Diff	Difference in minutes
Months Diff	Difference in months
Years Diff	Difference in years
Start Of Day	Midnight of date
Start Of Hour	Beginning of hour
Start Of Month	First day of month
Ticks	Timestamp as ticks
Parse DateTime	Convert string to date
Convert From UTC	UTC to local time
Convert To UTC	Local to UTC time

Operators Quick Reference

Category	Operators
Logical	And, Or
Equality	Is Equal To, Is Not Equal To
Numeric	Is Greater Than, Is Greater Than Or Equal To, Is Less Than, Is Less Than Or Equal To
String	Contains, Does Not Contain, Starts With, Does Not Start With, Ends With, Does Not End With
List	Contains Item, Does Not Contain Item
Null	Null, Not Null, Null Or Empty String, Not Null Or Empty String, Is True, Is False, Any