Yaya kake ƙira pagination, filtering, da sorting na collection endpoint?

Question

IT Interview Practice · Accepted Answer

Kowane endpoint da ke dawo da collection yana bukatar **iyakance da tsara** sakamako. Damuwoyi uku — pagination, filtering, sorting — duk suna zama a cikin query string.

## Pagination: offset vs cursor

**Offset (bisa page)** — `?page=3&limit=20` ko `?offset=40&limit=20`.
```http
GET /orders?offset=40&limit=20 HTTP/1.1
```
Mai sauƙi kuma yana ba da damar tsalle zuwa kowane page, amma yana da matsaloli biyu a manyan sikeli: `OFFSET 100000` yana tilasta database ya scan ya kuma zubar da rows 100k (jinkiri), kuma idan aka saka/share rows tsakanin requests, abubuwa suna **motsawa** kuma ka ga kwafi ko tsalle.

**Cursor (keyset)** — client yana wuce da pointer mara haske zuwa abu na ƙarshe da aka gani.
```http
GET /orders?limit=20&cursor=eyJpZCI6MTAyMH0 HTTP/1.1
```
```http
HTTP/1.1 200 OK

{
  "data": [ /* 20 orders */ ],
  "page": { "next_cursor": "eyJpZCI6MTA0MH0", "has_more": true }
}
```
Server yana fassara cursor zuwa `WHERE id > 1020 ORDER BY id LIMIT 20` — lookup mai index da ke ci gaba da sauri a kowane zurfi kuma **mai ƙarko** kan inserts. Trade-off: babu damar shiga bazuwar zuwa "page 500".

```text
Offset  → small datasets, admin UIs, "jump to page N"
Cursor  → large/infinite feeds, real-time data, mobile scroll
```

## Filtering da sorting

```http
GET /orders?status=shipped&min_total=100&sort=-created_at,id HTTP/1.1
```
- **Filter** da query params na field=value (`status=shipped`). Whitelist ɗin fields da aka yarda.
- **Sort** da param na `sort`; prefix na `-` yana nufin saukowa (descending) (`-created_at`). Tallafa multi-key don tsari mai ƙarko.
- Kullum **iyakance `limit`** (misali max 100) don client ba zai iya neman rows miliyan ba.

## Me ya sa yake da muhimmanci

Wannan na ɗaya daga cikin tambayoyin ƙira na API da suka fi amfani domin kusan kowane list endpoint yana fuskantar sa, kuma zaɓin yana da sakamako na gaske na aiki. Mai hira yawanci yana bincike **trade-off ɗin offset-vs-cursor**: ɗan takara da ke kama offset pagination ko'ina bai ji zafin `OFFSET 1000000` yana scan ɗin table ba, ko bug na "sakamako masu motsawa" inda mai amfani da ke scroll ɗin feed mara iyaka ke ganin post iri ɗaya sau biyu domin an saka sabo. Cursor pagination yana gyara duka biyu ta hanyar mai da query zuwa keyset lookup mai index, shi ya sa kowane API na babban sikeli (Twitter, Stripe, Slack) ke amfani da shi ga feeds. Amsoshi masu ƙarfi suna kuma ambaton kariyar aiki — whitelist ɗin fields na filter/sort (don gujewa queries marasa index da injection) da iyakance `limit` (don kare database) — wanda ke rarrabe wanda ya gudanar da waɗannan endpoints a production da wanda ya karanta game da su kawai.

Pagination: offset vs cursor

Filtering da sorting

Me ya sa yake da muhimmanci

Tambayoyi masu alaƙa