2. Calculations

Calculations

ObjectSemantics.NET supports lightweight calculation expressions directly in templates.

Supported Functions

You can use function names with or without leading underscores.

Function	Purpose	Example
sum(path)	Sum numeric values in a path	{{ _sum(Customer.Payments.Amount):N2 }}
avg(path)	Average numeric values in a path	{{ _avg(Customer.Payments.PaidAmount):N2 }}
count(path)	Count non-null values in a path	{{ _count(Customer.Payments.Amount) }}
min(path)	Minimum numeric value in a path	{{ _min(Customer.Payments.Amount):N2 }}
max(path)	Maximum numeric value in a path	{{ _max(Customer.Payments.Amount):N2 }}
calc(expr)	Arithmetic over properties/literals	{{ _calc(PaidAmount - Customer.CreditLimit):N2 }}

Aggregates

Example model shape:

Customer.Payments = [
  { Amount = 1000 },
  { Amount = 2000 },
  { Amount = 1500 }
];

Examples:

{{ _sum(Customer.Payments.Amount) }}        -> 4500
{{ _avg(Customer.Payments.Amount):N2 }}     -> 1,500.00
{{ _count(Customer.Payments.Amount) }}      -> 3
{{ _min(Customer.Payments.Amount) }}        -> 1000
{{ _max(Customer.Payments.Amount) }}        -> 2000

Arithmetic with calc

Operators:

• +
• -
• *
• /
• Parentheses (...)

Examples:

{{ _calc(PaidAmount - Customer.CreditLimit):N2 }}
{{ _calc((Subtotal + Tax) * 0.5):N2 }}
{{ _calc(Quantity * UnitPrice) }}

Works Inside Loops

{{ #foreach(Items) }}
  [{{ Name }}={{ __calc(Quantity * UnitPrice):N2 }}]
{{ #endforeach }}

Behavior Rules

Scenario	Result
Valid numeric expression/path	Numeric output
Null source/property in math path	0
Unknown path/property in expression	Empty
Non-numeric data in numeric expression (e.g. string/date for sum)	Empty
Invalid expression syntax	Empty

Notes:

• These rules apply to sum, avg, count, min, max, and calc.
• Standard placeholder behavior is different: unknown regular properties remain unresolved ({{ UnknownProp }}).

Formatting Calculated Results

Calculation results can use normal format specifiers:

{{ _sum(Customer.Payments.Amount):N2 }}
{{ _calc(PaidAmount - CreditLimit):#,##0 }}

Or no format at all:

{{ _sum(Customer.Payments.Amount) }}
{{ _calc(PaidAmount - CreditLimit) }}