objGet

Reads a nested value out of an object by path, returning a fallback when the path is not there.

The path takes both dot and bracket notation, and the two can be mixed: a.b.c, list[0], list[1].d and list.1.d all work. A bracket may carry a quoted key, so ["a.b"] reads one key named a.b instead of walking two levels.

Whether a step exists is decided by the presence of the key, not by the value behind it, so a stored nullNone is returned as it is rather than replaced by the fallback.

Arrays are walked with their numeric index. The fallback is returned as soon as a step is missing, when the path runs into a value that cannot be walked any further, or when the object itself is not an object.

Parameters

Name	Type	Required	Default
obj	objectMap<String, dynamic>dict	●	–
The object to read from.
path	stringStringstr	●	–
The path to the value, in dot and/or bracket notation.
optionsnamedkeyword	ObjGetOptions	–	–
Lookup options. See the table below.

namedThese parameters are passed as named parameters.

keywordThese parameters are passed as keyword arguments, or as a single dict in their place.

ObjGetOptions

Name	Type	Required	Default
fallback	anydynamicAny	–	nullNone
Returned when the path is not there.

Returns

any

dynamic

Any

Examples

const data = { a: { b: { c: 42 } }, list: [1, { d: 'x' }] };

objGet(data, 'a.b.c'); // Returns 42
objGet(data, 'list[0]'); // Returns 1
objGet(data, 'list[1].d'); // Returns 'x'
objGet(data, 'a.zzz'); // Returns null
objGet(data, 'a.zzz', { fallback: 'none' }); // Returns 'none'
objGet({ 'a.b': 1 }, '["a.b"]'); // Returns 1

final data = {'a': {'b': {'c': 42}}, 'list': [1, {'d': 'x'}]};

objGet(data, 'a.b.c'); // Returns 42
objGet(data, 'list[0]'); // Returns 1
objGet(data, 'list[1].d'); // Returns 'x'
objGet(data, 'a.zzz'); // Returns null
objGet(data, 'a.zzz', fallback: 'none'); // Returns 'none'
objGet({'a.b': 1}, '["a.b"]'); // Returns 1

data = {'a': {'b': {'c': 42}}, 'list': [1, {'d': 'x'}]}

objGet(data, 'a.b.c')  # Returns 42
objGet(data, 'list[0]')  # Returns 1
objGet(data, 'list[1].d')  # Returns 'x'
objGet(data, 'a.zzz')  # Returns None
objGet(data, 'a.zzz', {'fallback': 'none'})  # Returns 'none'
objGet({'a.b': 1}, '["a.b"]')  # Returns 1