Mbinu bora za usanifu wa schema ya GraphQL ni zipi?

Question

IT Interview Practice · Accepted Answer

Schema nzuri ni **inayoendeshwa na client, inayoruhusu null kwa msingi kwenye pembeni, na inayoweza kubadilika bila versions**. Humodeli domain kwa maneno ambayo clients hutumia kweli, si tables za database yako.

## Nullability

Fanya field kuwa non-null (`!`) tu unapoweza *daima* kuirudisha. Kutumia `!` kupita kiasi ni mtego: ikiwa field ya non-null itapata kosa, huweka null object nzima ya parent yake, ikigeuza kushindwa kudogo kuwa nafasi tupu kubwa. Pendelea inayoruhusu null kwa chochote kinachotegemea huduma ya chini (downstream).

```graphql
type User {
  id: ID!             # truly always present
  email: String!      # required in your DB -> safe as non-null
  avatarUrl: String   # comes from an external service -> nullable, so its failure is isolated
}
```

## Kuita majina & inputs

- Tumia majina thabiti, ya kueleweka; booleans husomeka kama vitabiri (`isPublished`).
- Ipe kila mutation type moja ya **`input`** na irudishe type ya **payload** — unaweza kuongeza fields baadaye bila kuvunja saini.

```graphql
input CreatePostInput { title: String!, body: String! }
type CreatePostPayload { post: Post!, errors: [UserError!]! }  # room to grow
type Mutation { createPost(input: CreatePostInput!): CreatePostPayload! }
```

## Mageuzi bila versioning

GraphQL huepuka URLs za `/v2`. Unabadilika **kwa nyongeza (additively)**: ongeza fields kwa uhuru, na ustaafu za zamani kwa `@deprecated` clients zikihama.

```graphql
type User {
  fullName: String!
  name: String! @deprecated(reason: "Use fullName")   # keep serving until clients move off
}
```

Kuondoa au kubadili jina la field ndio mabadiliko pekee ya kuvunja kweli, hivyo sanifu ili mara chache uhitaji kufanya hivyo. Pia epuka kuvuja umbo la DB (weka wazi `fullName`, si `first_name`/`last_name` ikiwa clients wanataka field moja).

## Kwa nini ni muhimu

Chaguzi hizi ndizo zinazotofautisha schema inayodumu miaka na ile ambayo clients hupambana nayo. Wahoji hutumia hili kupima **ukomavu wa usanifu wa API** — hasa maafikiano ya nullability/error na fikra ya mageuzi ya nyongeza, ambazo ni za kipekee kwa GraphQL.

Nullability

Kuita majina & inputs

Mageuzi bila versioning

Kwa nini ni muhimu

Maswali yanayohusiana