objInvert

Returns a new object with the keys and values swapped: every value becomes a key, and the key it came from becomes its value.

Keys are always strings, so the value is converted to text first. nullNone becomes 'null', trueTrue becomes 'true', and a number that happens to be whole is written without a fractional part in every language, so 1.0 becomes '1' in Dart and Python just as it does in JavaScript.

Only the top level is inspected, and when two entries share a value the later one wins, because both land on the same key. Values that are not a string, a number, a boolean or nullNone have no meaningful text form — the result for those is whatever the language prints and is not part of the API.

The original object is not modified. If the argument is not an object, nullNone is returned.

One note on iteration order: a JavaScript object always enumerates integer-like keys first, so objInvert({ a: 'x', b: 1 }) iterates 1 before x there while Dart and Python keep the insertion order. The entries themselves are identical in all three.

Parameters

Name	Type	Required	Default
obj	objectMap<String, dynamic>dict	●	–
The object to invert. It is not modified.

Returns

object | null

Map<String, String>?

dict | None

Examples

objInvert({ a: 1, b: 2 }); // Returns { '1': 'a', '2': 'b' }
objInvert({ a: 'x', b: 'y' }); // Returns { x: 'a', y: 'b' }
objInvert({ a: 1, b: 1 }); // Returns { '1': 'b' }
objInvert({ a: true, b: null }); // Returns { true: 'a', null: 'b' }

objInvert({'a': 1, 'b': 2}); // Returns {'1': 'a', '2': 'b'}
objInvert({'a': 'x', 'b': 'y'}); // Returns {'x': 'a', 'y': 'b'}
objInvert({'a': 1, 'b': 1}); // Returns {'1': 'b'}
objInvert({'a': true, 'b': null}); // Returns {'true': 'a', 'null': 'b'}

objInvert({'a': 1, 'b': 2})  # Returns {'1': 'a', '2': 'b'}
objInvert({'a': 'x', 'b': 'y'})  # Returns {'x': 'a', 'y': 'b'}
objInvert({'a': 1, 'b': 1})  # Returns {'1': 'b'}
objInvert({'a': True, 'b': None})  # Returns {'true': 'a', 'null': 'b'}