ColumnOperation class abstract

A single declarative transformation applied to one raw entity map during a schema migration.

Use the factory shorthands for the common cases:

ColumnOperation.add('priority', defaultValue: 0);
ColumnOperation.add('slug', compute: (row) => (row['title'] as String).toLowerCase());
ColumnOperation.rename('title', to: 'name');
ColumnOperation.remove('legacyField');
ColumnOperation.transform('createdAt', (value, row) => DateTime.parse(value as String).toUtc().toIso8601String());
ColumnOperation.row((row) => {...row, 'fullName': '${row['first']} ${row['last']}'});

Implement this class directly for reusable custom operations.

Implementers

• AddColumn
• RemoveColumn
• RenameColumn
• RowTransform
• SchemaRenameOperation
• TransformColumn

Constructors

ColumnOperation()

const

ColumnOperation.add(String name, {Object? defaultValue, Object? compute(Map<String, dynamic> row)?, bool overwrite = false, String? sqlType, String? sqlExpression})

Adds a column named name.

factory

ColumnOperation.remove(String name)

Removes the column named name if present.

factory

ColumnOperation.rename(String from, {required String to})

Moves the value under from to the key to. Rows without from are left unchanged.

factory

ColumnOperation.row(Map<String, dynamic> transform(Map<String, dynamic> row), {List<String>? sql})

Applies an arbitrary whole-row rewrite. The returned map replaces the row entirely, so spread the input to keep untouched columns: ColumnOperation.row((row) => {...row, 'v': 2}).

factory

ColumnOperation.transform(String name, Object? transform(Object? value, Map<String, dynamic> row), {bool applyIfAbsent = false, String? sqlExpression})

Replaces the value of name with transform(value, row).

factory

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

apply(Map<String, dynamic> row) → Map<String, dynamic>

Applies this operation to row and returns the resulting row.

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