XWidget EL Logo

XWidget EL

A powerful expression language for XWidget that enables dynamic evaluation of expressions within XML markup. Supports arithmetic, logical, conditional, and relational operators, along with 50+ built-in functions, instance method chaining, and custom function registration.

<Text data="${user.firstName + ' ' + user.lastName}"/>
<Text visible="${items.length > 0}" data="Found ${length(items)} items"/>
<Container color="${isActive ? toColor('#00FF00') : toColor('#FF0000')}"/>

Features

  • Full Operator Support — Arithmetic (+, -, *, /, ~/, %), logical (&&, ||, !), relational (<, >, <=, >=, ==, !=), ternary (? :), and null-coalescing (??)
  • 50+ Built-in Functions — Type conversions, string manipulation, collection queries, date/time formatting, math operations, and validators
  • Instance Method Chaining — Call methods directly on values: ${name.toUpperCase().trim()}
  • Custom Functions — Register your own functions on any Dependencies instance
  • Null Safety — Null-coalescing, null-safe property access, and null-checking functions built in
  • Type-Aware Operations — DateTime arithmetic, Duration math, Enum comparison, and automatic type coercion
  • Reactive Data Model — Dependencies class with dot/bracket notation, global data, and change notifications via ValueNotifier
  • Data Modeling — Structured models with property transformers, type converters, translations, and instance management

Quick Start

flutter pub add xwidget_el

If you're using XWidget, xwidget_el is included automatically as a dependency.

Expressions are evaluated within ${...} delimiters in XML attributes:

<!-- References -->
<Text data="${user.name}"/>

<!-- Arithmetic -->
<Text data="${toString(price * quantity)}"/>

<!-- Conditionals -->
<Text data="${isVip ? 'Welcome back!' : 'Hello!'}"/>

<!-- Function calls -->
<Text data="${formatDateTime('yyyy-MM-dd', now())}"/>

<!-- Method chaining -->
<Text data="${title.trim().toUpperCase()}"/>

<!-- Null coalescing -->
<Text data="${user.nickname ?? user.firstName}"/>

Documentation

Full documentation is available at docs.xwidget.dev, including:

License

See LICENSE for details.

Libraries

xwidget_el