JSON を TypeScript 型に変換する方法

问题

JSON の API レスポンスがあり、コンパイル時の安全性と自動補完を得るために TypeScript の型が欲しい。

前提条件

• JSON の理解
• TypeScript の型とインターフェースの理解

ステップ

1. 1. Analyze the JSON structure

   The converter inspects the JSON to determine field types. Strings become string, numbers become number, booleans become boolean, null becomes null, arrays become T[], and objects become nested interfaces. Field names become property names.

   入力

   {"name":"Alice","age":30}

   输出

   types: name→string, age→number

2. 2. Generate TypeScript interfaces

   Produce interface declarations with typed properties. Nested objects become separate interfaces. Union types are generated for fields that can be multiple types. Optional properties (undefined) are marked with ?.

   入力

   JSON object

   输出

   interface MyData { name: string; age: number; }

3. 3. Refine the generated types

   Review the output and refine: use more specific types (string literals for enums, Date for date strings), rename interfaces for clarity, and add JSDoc comments. Consider making some fields optional if they are not always present in the API response.

   入力

   raw interface

   输出

   refined, documented types

期待される結果

JSON 構造を正確に記述し、型安全な開発を可能にする TypeScript インターフェース。

よくあるエラー

All fields marked as required

If some fields are optional in the API, mark them with ? in the interface. A single sample cannot determine optionality.

Date strings typed as string

JSON has no Date type. Manually change date string fields to Date or use a branded type for runtime parsing.

トラブルシューティング指引

• If the types are too loose, add string literal types for enum-like fields.
• For arrays of mixed types, use union types or discriminated unions.

セキュリティ上の制限

• Type generation is a static analysis. No data is transmitted or executed.