Expressions

The expression engine allows you to add dynamic logic to templates. Use expressions for text interpolation, conditional rendering, and data transformation.

Syntax

Expressions use double curly braces: {{expression}}

Simple Variables

{{title}}
{{user.name}}
{{items[0].price}}

Property Access

Access nested properties with dot notation:

{{user.profile.avatar}}
{{order.items[0].name}}

Arithmetic

{{price * quantity}}
{{subtotal + tax}}
{{total / 100}}
{{count % 2}}

Comparisons

{{price > 100}}
{{status == 'active'}}
{{count >= 10}}
{{name != 'Guest'}}

Logical Operators

{{isAdmin && isPremium}}
{{hasDiscount || isFirstOrder}}
{{!isExpired}}

Ternary Operator

{{isPremium ? 'Premium Member' : 'Free User'}}
{{count > 0 ? count : 'None'}}

Built-in Functions

String Functions

Function	Description	Example
`uppercase(str)`	Convert to uppercase	`{{uppercase(name)}}`
`lowercase(str)`	Convert to lowercase	`{{lowercase(email)}}`
`capitalize(str)`	Capitalize first letter	`{{capitalize(title)}}`
`titleCase(str)`	Capitalize each word	`{{titleCase(name)}}`
`trim(str)`	Remove whitespace	`{{trim(input)}}`
`truncate(str, len, suffix)`	Truncate with suffix	`{{truncate(desc, 100, '...')}}`
`replace(str, search, replace)`	Replace all occurrences	`{{replace(text, '-', ' ')}}`
`split(str, delimiter)`	Split into array	`{{split(tags, ',')}}`
`padStart(str, len, char)`	Pad from start	`{{padStart(id, 5, '0')}}`
`padEnd(str, len, char)`	Pad from end	`{{padEnd(code, 10, '-')}}`

Number Functions

Function	Description	Example
`round(num, decimals)`	Round to decimals	`{{round(price, 2)}}`
`floor(num)`	Round down	`{{floor(rating)}}`
`ceil(num)`	Round up	`{{ceil(shipping)}}`
`abs(num)`	Absolute value	`{{abs(difference)}}`
`min(a, b, ...)`	Minimum value	`{{min(price, maxPrice)}}`
`max(a, b, ...)`	Maximum value	`{{max(0, quantity)}}`
`sum(array)`	Sum array values	`{{sum(prices)}}`
`average(array)`	Average of array	`{{average(ratings)}}`

Formatting Functions

Function	Description	Example
`currency(num, currency, locale)`	Format as currency	`{{currency(price, 'USD')}}`
`number(num, locale)`	Format number	`{{number(count, 'en-US')}}`
`percent(num, decimals)`	Format as percent	`{{percent(rate, 1)}}`
`date(str, format)`	Format date	`{{date(createdAt, 'MMM D, YYYY')}}`
`time(str)`	Format time	`{{time(timestamp)}}`

Array Functions

Function	Description	Example
`length(arr)`	Array length	`{{length(items)}}`
`first(arr)`	First element	`{{first(images)}}`
`last(arr)`	Last element	`{{last(comments)}}`
`join(arr, separator)`	Join elements	`{{join(tags, ', ')}}`
`slice(arr, start, end)`	Slice array	`{{slice(items, 0, 3)}}`
`contains(arr, value)`	Check if contains	`{{contains(roles, 'admin')}}`
`indexOf(arr, value)`	Find index	`{{indexOf(items, 'apple')}}`

Type Checks

Function	Description	Example
`isEmpty(val)`	Check if empty	`{{isEmpty(items)}}`
`isNotEmpty(val)`	Check if not empty	`{{isNotEmpty(name)}}`
`isDefined(val)`	Check if defined	`{{isDefined(user)}}`
`isArray(val)`	Check if array	`{{isArray(items)}}`
`isString(val)`	Check if string	`{{isString(name)}}`
`isNumber(val)`	Check if number	`{{isNumber(count)}}`

Utilities

Function	Description	Example
`default(val, fallback)`	Default if empty	`{{default(name, 'Guest')}}`
`coalesce(a, b, ...)`	First non-null	`{{coalesce(nickname, name, 'User')}}`
`json(val)`	To JSON string	`{{json(data)}}`
`parseJson(str)`	Parse JSON	`{{parseJson(jsonString)}}`

Conditional Rendering

If/Else in Text

{{isPremium ? 'Premium Member' : 'Free User'}}

Conditional Objects

In template objects, use the _if property:

{
  "type": "textbox",
  "text": "Premium Badge",
  "_if": "isPremium"
}

The object is only rendered if the condition evaluates to true.

Complex Conditions

{
  "type": "image",
  "src": "{{badge}}",
  "_if": "isPremium && !isExpired"
}

Text Interpolation

Combine static text with expressions:

Hello, {{name}}! You have {{count}} {{count == 1 ? 'message' : 'messages'}}.

Multiple expressions in one string:

{{currency(price, 'USD')}} ({{percent(discount)}} off)

Testing Expressions

Test expressions before using them in templates:

Validate Syntax

curl -X POST https://api.pictify.io/templates/expression/validate \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"expression": "price * quantity"}'

Response:

{
  "valid": true,
  "expression": "price * quantity"
}

Test with Data

curl -X POST https://api.pictify.io/templates/expression/test \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "expression": "currency(price * quantity, 'USD')",
    "variables": {
      "price": 29.99,
      "quantity": 3
    }
  }'

Response:

{
  "success": true,
  "result": "$89.97",
  "resultType": "string"
}

List Available Functions

curl https://api.pictify.io/templates/expression/functions \
  -H "Authorization: Bearer $API_KEY"

Examples

Personalized Greeting

{{capitalize(greeting)}}, {{titleCase(name)}}!

Price Display

{{currency(price, 'USD')}}{{hasDiscount ? ' (' + percent(discount) + ' off)' : ''}}

Date Formatting

Published {{date(publishedAt, 'MMMM D, YYYY')}}

Conditional Badge

{
  "type": "rect",
  "fill": "{{isPremium ? '#FFD700' : '#C0C0C0'}}",
  "_if": "showBadge"
}

Array Display

{{join(slice(tags, 0, 3), ' • ')}}{{length(tags) > 3 ? ' +' + (length(tags) - 3) + ' more' : ''}}

Getting Started

Concepts

Security

Resources

Expressions

Expressions

Syntax

Simple Variables

Property Access

Arithmetic

Comparisons

Logical Operators

Ternary Operator

Built-in Functions

String Functions

Number Functions

Formatting Functions

Array Functions

Type Checks

Utilities

Conditional Rendering

If/Else in Text

Conditional Objects

Complex Conditions

Text Interpolation

Testing Expressions

Validate Syntax

Test with Data

List Available Functions

Examples

Personalized Greeting

Price Display

Date Formatting

Conditional Badge

Array Display

​Expressions

​Syntax

​Simple Variables

​Property Access

​Arithmetic

​Comparisons

​Logical Operators

​Ternary Operator

​Built-in Functions

​String Functions

​Number Functions

​Formatting Functions

​Array Functions

​Type Checks

​Utilities

​Conditional Rendering

​If/Else in Text

​Conditional Objects

​Complex Conditions

​Text Interpolation

​Testing Expressions

​Validate Syntax

​Test with Data

​List Available Functions

​Examples

​Personalized Greeting

​Price Display

​Date Formatting

​Conditional Badge

​Array Display

Expressions

Syntax

Simple Variables

Property Access

Arithmetic

Comparisons

Logical Operators

Ternary Operator

Built-in Functions

String Functions

Number Functions

Formatting Functions

Array Functions

Type Checks

Utilities

Conditional Rendering

If/Else in Text

Conditional Objects

Complex Conditions

Text Interpolation

Testing Expressions

Validate Syntax

Test with Data

List Available Functions

Examples

Personalized Greeting

Price Display

Date Formatting

Conditional Badge

Array Display