Expression Fields Reference

Placeholder Basics

Placeholders substitute field values from the current asset into your expression. Wrap any field name in double curly braces.

// Substitute a field value
{{serialNumber}}                     → SN-00452

// Multiple placeholders
{{make}} {{model}}                   → Dell XPS 15

// Concatenate with a space
{{first}} + " " + {{last}}           → John Smith

// Numeric operations
{{quantity}} + {{spares}}            → 15
{{width}} * {{height}}               → 200
{{total}} / 3                        → 33.33

Missing Placeholders

Missing placeholders resolve to null. Add fallback logic when a value is optional:

// Use fallback if field is missing
{{nickname}} ?? {{displayName}}      → displayName if nickname is null
{{optional}} || "Not provided"       → "Not provided" if optional is empty

Context Variables

Special context variables provide access to related location and loan data using dotted placeholders.

$location

Access the asset’s location hierarchy:

// Display full location path
{{$location.parentLocationName}} + " > " + {{$location.name}}
→ Building A > Room 101

// Fallback through location hierarchy
{{$location.grandparentLocationName}} ?? {{$location.parentLocationName}} ?? {{$location.name}}
→ Returns the highest available level

$loan

Access checkout and loanee details for assets currently on loan:

// Display who has the asset
"Checked out to: " + {{$loan.loaneeName}}
→ Checked out to: Jane Doe

// Show loanee with title
{{$loan.loaneeName}} + " (" + {{$loan.loaneeTitle}} + ")"
→ Jane Doe (IT Manager)

// Display due date
"Due: " + {{$loan.due}}
→ Due: 2024-04-15

Standard Math Operations

Math expressions containing numerics, parentheses, and operators + - * / % are evaluated with normal precedence after placeholders resolve. Unary +/- are supported for negative numbers.

// Basic arithmetic
{{quantity}} + {{spares}}            → 15
{{total}} - {{discount}}             → 85
{{price}} * {{quantity}}             → 499.50
{{total}} / 4                        → 25

// Modulo (remainder)
{{count}} % 5                        → 2

// Negative values
-{{debt}} + 10                       → -90

// Grouped operations (parentheses)
({{a}} + {{b}}) * {{c}}              → 30
{{a}} + {{b}} * {{c}}                → 22 (multiplication first)

// Area calculation
{{width}} * {{height}}               → 200

// Calculate total with tax
{{price}} + ({{price}} * 0.08)       → 107.99

Text Filters

Apply filters after a placeholder using the pipe (|) operator. Multiple filters chain from left to right.

// Convert to uppercase
{{code | uppercase}}                 → ABC-123

// Convert to lowercase
{{name | lowercase}}                 → john doe

// Convert to title case
{{fullName | titlecase}}             → John Doe

// Chain multiple filters
{{name | lowercase | titlecase}}     → John Doe

// Filter on status field
{{status | uppercase}}               → ACTIVE

// Combine with concatenation
"Status: " + {{status | uppercase}}  → Status: ACTIVE

Date Math

Add or subtract time from date values. Date offsets work on either side of the operator.

// Add years (calculate warranty expiry)
{{purchaseDate}} + 5 years           → 2029-01-15

// Add months
{{startDate}} + 6 months             → 2024-07-15

// Add weeks
{{orderDate}} + 2 weeks              → 2024-02-01

// Add days
{{createdDate}} + 30 days            → 2024-02-14

// Add hours
{{startTime}} + 3 hours              → 2024-01-15 11:00

// Subtract time
{{shipDate}} - 2 weeks               → 2024-01-01
{{expiryDate}} - 6 months            → 2023-07-15

// Offset on left side
3 months + {{purchaseDate}}          → 2024-04-15

// Calculate review date (90 days from purchase)
{{purchaseDate}} + 90 days           → 2024-04-14

Comparisons and Truthiness

Use comparison operators to build boolean logic. Truthy/falsy follow PHP rules: non-empty strings and non-zero numbers are truthy.

Comparison Operators

// Equality
{{status}} == "retired"              → true
{{status}} == "active"               → false

// Inequality
{{status}} != "active"               → true

// Numeric comparisons
{{quantity}} > 10                    → true
{{quantity}} >= 10                   → true
{{count}} < 5                        → false
{{count}} <= 5                       → true

Logical Operators

// OR - returns first truthy value
{{primary}} || {{secondary}}         → primary (if truthy)
{{nickname}} || {{fullName}}         → fullName (if nickname empty)
{{value}} || "default"               → "default" (if value empty)

// Null coalescing - returns first non-null (keeps empty strings)
{{nickname}} ?? {{displayName}}      → "" (if nickname is empty string)
{{optional}} ?? "fallback"           → "fallback" (if optional is null)

Conditionals

Branch inside an expression to return different values based on conditions. These constructs can nest; each branch is itself an expression that can include placeholders, filters, or more conditionals.

Function Style

// $if(condition, valueIfTrue, valueIfFalse)
$if({{status}} == "retired", "Do not loan", "Available")
→ "Do not loan"

$if({{quantity}} > 0, {{name}}, "Out of stock")
→ "Laptop" or "Out of stock"

$if({{checkedOut}}, "Checked Out", {{status}} | uppercase)
→ "Checked Out" or "AVAILABLE"

Ternary Operator

// condition ? valueIfTrue : valueIfFalse
{{checkedOut}} ? "Checked out" : "On shelf"
→ "Checked out" or "On shelf"

{{quantity}} > 0 ? "In stock" : "Sold out"
→ "In stock" or "Sold out"

{{isActive}} ? {{name}} : "Inactive: " + {{name}}
→ "Laptop" or "Inactive: Laptop"

Nested Conditionals

// Multiple levels of conditions
{{a}} ? ({{b}} ? "both" : "a only") : "neither"
→ "both", "a only", or "neither"

$if({{quantity}} > 100, "High", $if({{quantity}} > 10, "Medium", "Low"))
→ "High", "Medium", or "Low"

Fallback Patterns

// Null coalescing - first non-null value
{{nickname}} ?? {{displayName}}
→ Uses nickname if not null, otherwise displayName

// Logical OR - first truthy value
{{primary}} || {{secondary}}
→ Uses primary if truthy, otherwise secondary

// Multi-level fallback
{{nickname}} ?? {{preferredName}} ?? {{fullName}}
→ First non-null value in chain

String Handling

Understanding string concatenation and type coercion helps avoid unexpected results.

// Basic concatenation
{{make}} + " " + {{model}}           → "Dell XPS 15"

// Quoted strings preserve spacing
"Asset: " + {{name}}                 → "Asset: Laptop"

// Escape quotes inside strings
"A \"quoted\" label"                 → A "quoted" label

// Plus signs inside quotes are literal text
"1 + 1 = 2"                          → "1 + 1 = 2"

// String coercion: if one side is a string, both become strings
"Total: " + {{price}} + {{tax}}      → "Total: 9910" (not math!)

// Use parentheses to force math first
"Total: " + ({{price}} + {{tax}})    → "Total: 109"

// Area with unit label
"Area: " + ({{width}} * {{height}}) + " sq ft"
→ "Area: 200 sq ft"

// Arrays or objects resolve to empty string
{{items}} + " items"                 → " items" (if items is an array)