Expr class

Helper class for building expressions in a type-safe, fluent manner.

This class provides a builder pattern that prevents injection attacks by only allowing structured expression construction.

All atomic field operations (increment, multiply, etc.) can be expressed using this unified expression system.

Example usage:

// Simple expression: price * quantity
Expr.field('price') * Expr.field('quantity')

// Increment: balance + 100
Expr.field('balance') + Expr.value(100)

// Multiply: price * 0.9 (10% discount)
Expr.field('price') * Expr.value(0.9)

// Complex expression with parentheses: (price * quantity) + tax - discount
(Expr.field('price') * Expr.field('quantity')) + Expr.field('tax') - Expr.field('discount')

// Multi-level parentheses: ((a + b) * c) / (d - e)
((Expr.field('a') + Expr.field('b')) * Expr.field('c')) / (Expr.field('d') - Expr.field('e'))

// Nested expressions with functions: min((price * quantity), maxPrice)
Expr.min(
  (Expr.field('price') * Expr.field('quantity')),
  Expr.field('maxPrice')
)

// Complex calculation: ((base * rate) + tax) * (1 - discount)
((Expr.field('base') * Expr.field('rate')) + Expr.field('tax')) * (Expr.value(1) - Expr.field('discount'))

// With functions: min(price, maxPrice)
Expr.min(Expr.field('price'), Expr.field('maxPrice'))

// Server timestamp
Expr.now()

Parentheses Support: The expression system fully supports parentheses for controlling evaluation order. Dart's operator precedence rules apply, and parentheses can be nested to any depth. The expression AST correctly represents the parenthesized structure.

Constructors

Expr()

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

abs(ExprNode x) → FunctionCall

Creates an absolute value function call: abs(x)

ceil(ExprNode x) → FunctionCall

Creates a ceil function call: ceil(x)

field(String fieldName) → FieldRef

Creates a field reference expression.

floor(ExprNode x) → FunctionCall

Creates a floor function call: floor(x)

ifElse(ExprNode condition, dynamic thenValue, dynamic elseValue) → IfElse

Conditional: if condition then thenValue else elseValue. Use with isUpdate/isInsert for update-vs-insert semantics.

isInsert() → IsInsert

Predicate: true when the current operation is an insert (e.g. upsert inserted new row).

isUpdate() → IsUpdate

Predicate: true when the current operation is an update (e.g. upsert matched existing row).

max(ExprNode a, ExprNode b) → FunctionCall

Creates a max function call: max(a, b)

min(ExprNode a, ExprNode b) → FunctionCall

Creates a min function call: min(a, b)

now() → TimestampExpr

Creates a server timestamp expression.

round(ExprNode x) → FunctionCall

Creates a round function call: round(x)

value(num value) → Constant

Creates a constant value expression.

when(ExprNode condition, dynamic value, {dynamic otherwise}) → When

Single-branch conditional: when condition holds use value, otherwise use otherwise (default null).