Expressions Functions

Functions

Transform data with string, date/time, math, and collection functions using the :functionName syntax.

String Functions

Function	Syntax	Example	Result
Upper	:upper	Name:upper	"JOHN"
Lower	:lower	Name:lower	"john"
Trim	:trim	Name:trim	"John" (whitespace removed)
Substring	:substring(start, length?)	Name:substring(0, 3)	"Joh"
Replace	:replace(old, new)	Name:replace('o', 'a')	"Jahn"
Concat	:concat(values...)	Name:concat(' ', LastName)	"John Doe"
Split	:split(separator)	Tags:split(',')	["a", "b", "c"]

Date/Time Functions

Function	Syntax	Example	Result
Year	:year	CreatedAt:year	2024
Month	:month	CreatedAt:month	12 (1-12)
Day	:day	CreatedAt:day	25 (1-31)
Hour	:hour	CreatedAt:hour	14 (0-23)
Minute	:minute	CreatedAt:minute	30 (0-59)
Second	:second	CreatedAt:second	45 (0-59)
Day of Week	:dayOfWeek	CreatedAt:dayOfWeek	1 (Sun=0...Sat=6)
Days Ago	:daysAgo	CreatedAt:daysAgo	5 (days from date to today)
Format	:format(pattern)	CreatedAt:format('yyyy-MM-dd')	"2024-12-25"

Math Functions

Function	Syntax	Example	Description
Round	:round(decimals?)	Price:round(2)	Round to 2 decimal places
Floor	:floor	Price:floor	Round down
Ceiling	:ceil	Price:ceil	Round up
Absolute	:abs	Balance:abs	Absolute value
Add	:add(operand)	Price:add(Tax)	Addition
Subtract	:subtract(operand)	Price:subtract(10)	Subtraction
Multiply	:multiply(operand)	Price:multiply(Quantity)	Multiplication
Divide	:divide(operand)	Total:divide(2)	Division
Modulo	:mod(divisor)	Value:mod(3)	Modulo operation
Power	:pow(exponent)	Value:pow(2)	Exponentiation

Note: Operand can be a number literal or property reference.

Collection Functions

Function	Syntax	Example	Description
Where	:where(condition)	Orders:where(Status = 'Done')	Keep the items that match the condition
OrderBy	`:orderBy(Key [asc	desc], ...)`	Orders:orderBy(Date desc)
Offset	:offset(n)	Orders:offset(5)	Skip the first n items
Limit	:limit(n)	Orders:limit(10)	Keep at most n items
First	:first	Orders:orderBy(Date):first	The first item, or null if the collection is empty
Last	:last	Orders:orderBy(Date):last	The last item, or null if the collection is empty
Distinct	:distinct(property)	Items:distinct(Name)	Get unique property values
Count	:count	Items:count	Count items in collection

Filtering, sorting and paging have their own page with the details and the limits: Filters, Sorting & Paging.

Chained Functions

Functions can be chained together as long as the output type matches the input type:

# String chaining
Name:trim:upper:substring(0, 3)          # "  john  " → "JOH"
 
# Math chaining
Price:add(Tax):round(2)                  # (Price + Tax) rounded to 2 decimals
 
# Date + Math
CreatedAt:year:add(1)                    # Year + 1
 
# Collection chaining
Items:distinct(Category):count           # Count unique categories

Usage Example

// The service that asks for the data
public class OrderResponse
{
    public string OrderId { get; set; }
 
    public string CustomerNameUpper { get; set; }
    public string CustomerNameClean { get; set; }
    public int OrderYear { get; set; }
    public string FormattedDate { get; set; }
    public int DaysOld { get; set; }
    public decimal RoundedTotal { get; set; }
    public decimal CalculatedTotal { get; set; }
    public int UniqueCategories { get; set; }
}
 
public class OrderResponseProfile : ProfileOf<OrderResponse>
{
    protected override void Configure() =>
        UseDistributedKey<OrderDistributedKey>()
            .Of(x => x.OrderId)
            // String functions
            .For(x => x.CustomerNameUpper, "Customer.Name:upper")
            .For(x => x.CustomerNameClean, "Customer.Name:trim:lower")
            // Date functions
            .For(x => x.OrderYear, "CreatedAt:year")
            .For(x => x.FormattedDate, "CreatedAt:format('yyyy-MM-dd')")
            .For(x => x.DaysOld, "CreatedAt:daysAgo")
            // Math functions
            .For(x => x.RoundedTotal, "Total:round(2)")
            .For(x => x.CalculatedTotal, "Price:multiply(Quantity):add(Tax)")
            // Collection functions
            .For(x => x.UniqueCategories, "Items:distinct(Category):count");
}

Each .For(...) takes the property to fill and the expression to run on the entity that owns the data. The owning service only needs the usual entity configuration.

Filter with Functions

Functions can be used within filter conditions:

# Orders with more than 5 items
Orders:where(Items:count > 5)
 
# Case-insensitive comparison
Users:where(Name:lower = 'john')
 
# Filter by year
Orders:where(CreatedAt:year = 2024)
 
# Filter by days ago
Orders:where(CreatedAt:daysAgo < 7)

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Source: https://fxmapper.net/docs/expressions/functions/ — the website is always the most up to date version.