Menene keys a cikin Flutter kuma yaushe kuke bukatar su?

Question

Accepted Answer

**Keys** a cikin Flutter suna taimakawa frayim don gano da kare widgets daidai-daidai akan sake ƙirƙira — kusan mahimma don **stateful widgets a jeri** waɗanda aka sake tsara, ƙari, ko cire. Fahimtar lokacin da ake bukatar keys yana saukaka ɓatacce masu daɗi da rudani.

## Menene keys ke yi

```text
During rebuilds, Flutter MATCHES new widgets to existing elements/state by POSITION and
TYPE. Usually this works fine. But when widgets of the SAME TYPE are reordered/added/
removed in a list, position-matching gets confused → state attaches to the WRONG widget.
→ KEYS give widgets a stable IDENTITY so Flutter matches them correctly across changes.
```

## Matsalar gida (babu keys)

```text
A list of STATEFUL widgets (e.g. items with their own state). You remove the FIRST item:
  ✗ WITHOUT keys → Flutter matches by position → the state stays at each position, so
    state appears attached to the WRONG items (state "shifts" incorrectly)
  ✓ WITH keys → Flutter matches by key → state follows the correct widget
→ This causes confusing bugs (wrong checkbox checked, wrong item highlighted, etc.).
```

```dart
// give list items stable keys (e.g. a unique id)
ListView(children: items.map((item) =>
  MyStatefulItem(key: ValueKey(item.id), item: item)   // stable identity
).toList())
```

## Nau'ikan keys da yaushe a yi amfani da su

```text
ValueKey → key by a value (e.g. an item's unique id) — common for list items
ObjectKey → key by an object's identity
UniqueKey → a guaranteed-unique key (forces a new identity each build — use carefully)
GlobalKey → a globally-unique key; access a widget's state/context from elsewhere
  (e.g. Form's GlobalKey) — powerful but heavier; use sparingly
WHEN NEEDED: mainly for STATEFUL widgets in dynamic lists (reorder/add/remove).
  Stateless widgets and static lists usually DON'T need keys.
```

## Me ya sa haka muhimmi

Fahimtar keys ita ce ilimi mai daraja na babbar mataki saboda ita tana warware **ɓataccen yada-yada da rudani** tare da stateful widgets a jerin abubuwa masu canji, da kuma sani lokacin da aka bukatar su ya nuna fahimta mai zurfafa na Flutter.

Bataccen aiki — cewa Flutter a gajeriyar yanayin ya haɗa widgets zuwa jiharsu ta hanyar **matsayi da nau'i** a lokacin sake ƙirƙira, wanda ke aiki daidai a gaida amma **ya karye lokacin da nau'ikan stateful widgets iri daya aka sake tsara, ƙari, ko cire a jeri** (sa da ake danganta da widget mara kyau) — ainihin tushen ɓataccen rudani ne (kiɓi bai yi aiki ba, abin da aka sanya alama ba daidai ba, jiha da ake da alama "yana waje" ba daidai ba). **Keys sun ba widgets tsarki mai tsiya** don da Flutter su danganta su daidai a baje-bajen canje-canjen, wajen warware irin waɗannan ɓataccen.

Fahimtar **matsalar gida** (cire abin waje daga jeri na stateful widgets babu keys waɗanda ake danganta ba daidai ba) da mafita (ba da waje tsarki mai tsiya kamar `ValueKey(item.id)`) shine ilimin aiki wanda ke warware waɗannan bayyanka rudani.

Fahimtar **nau'ikan keys** (ValueKey don danganta ta hanyar daraja kamar id — gida ga waje a jeri; ObjectKey; UniqueKey; da **GlobalKey** don samun shiga na jiha widget a waje, kamar GlobalKey na Form) da mahimman **lokacin da aka bukatar keys** (da farko don stateful widgets a jerin abubuwa masu canji; stateless widgets da jerin da ba su canja ba ba sa bukatar su gaije) shine bayyana fahimta mai girma — amfani da keys da daidai maimakon amfani da su ko'ina ko barin su inda aka bukatar su.

Saboda keys suna warware ainihin ɓataccen yada-yada tare da stateful widgets a jerin abubuwa masu canji (matsalar rudani wacce ƙuri'a masu buni da raini) da fahimtar lokacin da yaushe kuma yadda a yi amfani da su ya nuna fahimta mai zurfafa na Flutter, fahimtar keys ita ce ilimi mai daraja na babbar mataki — warware ajin ɓataccen rudani da jiha da nuna fahimta mai zurfi na iska na ƙirƙira Flutter wanda aka tsamani don babbar mataki, batu wanda ya saukar waɗanda suka gane gida na ƙirƙira na Flutter gida tun daidai da waɗanda kawai suke amfani da shi a fuskantagida.