Menene GraphQL schema? Bayyana scalar da object types.

Question

IT Interview Practice · Accepted Answer

**Schema** shi ne yarjejeniyar mai nau'i (typed contract) ta wani GraphQL API da aka rubuta a cikin SDL (Schema Definition Language). Yana bayyana kowane nau'i, kowane fili, da na musamman **root types** — `Query` (karatu), `Mutation` (rubutu), da kuma bisa zaɓi `Subscription` (kai tsaye). Uwar garke tana ƙi duk wata buƙata da ba ta dace da schema ba.

## Scalar da object types

- **Scalar types** su ne ganyayen ƙima (leaf values) da ke riƙe da ainihin bayanai: waɗanda aka gina ciki su ne `Int`, `Float`, `String`, `Boolean`, da `ID`. Kana kuma iya bayyana custom scalars kamar `DateTime`.
- **Object types** suna haɗa filaye tare. Filayensu na iya zama scalars *ko* wasu object types, wanda haka ne kake yin ƙirar dangantaka.

```graphql
scalar DateTime                # a custom scalar

type User {                    # an object type
  id: ID!                      # ! means non-null (always present)
  name: String!
  createdAt: DateTime!
  posts: [Post!]!              # a list of Post objects, non-null list of non-null items
}

type Post {
  id: ID!
  title: String!
  author: User!                # points back to User -> a relationship
}

type Query {                   # root type: the entry points for reads
  user(id: ID!): User          # a field with an argument; returns a User (nullable)
}
```

`!` yana nuna **non-null**; `[Post!]!` jeri ne mai non-null wanda abubuwansa ma non-null ne. Arguments (`id: ID!`) suna barin fili ya zama mai parameter.

## Me ya sa yake da muhimmanci

Schema shi ne tushen gaskiya guda ɗaya — yana tuƙa tabbatarwa (validation), takardun da ake samar da su ta atomatik, da client codegen. Karanta `!` da list types daidai wani abu ne da ake yawan gwadawa a hira ta matakin junior, kuma zaɓin nullability yana ƙirƙira yadda abokan ciniki suke ɗaukar kurakurai.

Scalar da object types

Me ya sa yake da muhimmanci

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