Migration from 2.1

Version 3.0 changes the default behavior of StringObjects::instance(). Stored values are returned unchanged, defaults apply only to missing or rejected values, and wildcard reads keep one entry per element. Composer constraints such as ^2.1 do not install 3.0 automatically, so existing applications keep working until you upgrade them deliberately.

Upgrading without behavior changes

Add the legacy option wherever you create an instance:

use StrObj\Behavior;
use StrObj\StringObjects;

$data = StringObjects::instance($input, ['behavior' => Behavior::LEGACY]);
$data = StringObjects::instance($input, ['behavior' => Behavior::LEGACY] + $options);

The legacy behavior keeps the 2.1 results; only the bug fixes listed below apply.

What changes with the default behavior

Behavior	Legacy (Behavior::LEGACY)	Default (consistent)
Stored false with a default	Returns the default	Returns false
Missing field with a default	Returns null	Returns the default
Value rejected by a filter	Returns false	Returns the default
Wildcard prefix/*/field	array_column(): missing elements skipped, later segments ignored	One entry per element (null when missing), every segment resolved
toArray()	Root fields; nested objects kept	Every nested object converted to arrays
Input and returned objects	Live references	Independent copies
Empty object root in toJson()	[]	{}
Filter callbacks	Closures only	Any callable
Casts that PHP cannot perform	Value returned unchanged	InvalidArgumentException
Filter precedence among wildcards	Configuration order	Most literal segments
required flag, byte limits	Coerced from scalars and numeric strings	Must be bool / int
Factory called on a subclass	Returns StringObjects	Returns the subclass

The complete table is in docs/compatibility.md.

Fixes that apply to both behaviors

• Deep writes keep the whole document.
• has() reports existing false and null fields correctly.
• Reads always reflect the current data; validation refreshes after writes.
• Numeric root keys (0/name) work on every PHP version.
• Library errors are exceptions (InvalidArgumentException, JsonException) instead of PHP Errors or warnings.

A safe migration path

1. Upgrade to 3.0 and add ['behavior' => Behavior::LEGACY] to every instance. Run your tests; only the listed bug fixes should be visible.
2. Add has() checks wherever your code compares get() results with false or null.
3. Remove the legacy option one module at a time and run its tests.
4. Search for code that relies on legacy-only results:
   • get(..., $default) on fields that can store false
   • count() or index access on wildcard results (legacy wildcards skip elements without the field, which can shift values between rows)
   • -> access on values returned by toArray()
   • code that mutates returned objects and expects the stored data to change
5. Replace those with explicit has() checks, set() calls and the aligned wildcard shape.