Message Syntax

Message Syntax

Plain Text Arguments

Use {key} markers to insert plain-text arguments into messages:

// Message: 'Hello, {name}!'
i18n.t('greeting', {'name': 'Alice'})
// Result: 'Hello, Alice!'

Rich Text Arguments

Use [key] markers to insert rich text arguments (resolved to InlineSpan):

// Message: 'Click [link]'
i18n.te('prompt', richArgs: {
  'link': TextSpan(
    text: 'here',
    style: TextStyle(color: Colors.blue),
  ),
})
// Result: TextSpan with clickable blue "here"

Pluralization

Use | (space-pipe-space) to separate singular and plural forms:

// Message: 'One item | {count} items'
i18n.tc('items', 1, {})         // Result: 'One item'
i18n.tc('items', 5, {'count': '5'}) // Result: '5 items'

Translation Methods

Method	Input	Returns	Purpose
t(key, args)	key and plain args	String	Translate with plain-text arguments
tc(key, count, args)	key, count, and plain args	String	Pluralize and translate with plain-text arguments
te(key, args, richArgs, style)	key, plain args, rich args, style	TextSpan	Translate with rich-text arguments
tce(key, count, args, richArgs, style)	key, count, plain args, rich args, style	TextSpan	Pluralize and translate with rich-text arguments

Edge Cases

Missing Arguments

If an argument is not provided, the literal marker is rendered:

// Message: 'Hello, {name}!'
i18n.t('greeting', {})
// Result: 'Hello, {name}!'

Null Argument Values

If an argument value is null, the string "null" is rendered:

// Message: 'Hello, {name}!'
i18n.t('greeting', {'name': null})
// Result: 'Hello, null!'

Plural with Missing Count

If count is null, the t() method returns the ENTIRE string including both forms separated by |:

// Message: 'One item | {count} items'
i18n.t('items')  // Returns raw message: 'One item | {count} items'
i18n.tc('items', null, {})  // Same: 'One item | {count} items'

Use tc() or tce() to select a plural form; they treat null count as non-singular (plural form used).

Arguments in Plural Forms

Arguments are interpolated within each form, not across the separator:

// Message: 'One {object} | {count} {objects}'
i18n.tc('count', 5, {'object': 'apple', 'count': '5', 'objects': 'apples'})
// Result: '5 apples'

Plural splitting happens BEFORE argument interpolation, so | in argument values do not break the split.