Field Selection

Field selection lets you request only the properties you need from the API. This reduces response size and provides automatic TypeScript type narrowing — the return type only includes the fields you selected.

Basic Field Selection

Both retrieve() and list() accept a fieldList option:

const issue = await client.issue.retrieve(12345, {
  fieldList: ['id', 'name', 'issueNumber', 'coverDate', 'volume'],
});

// TypeScript knows exactly what fields are available
console.log(issue.id); // number
console.log(issue.name); // string
console.log(issue.issueNumber); // number
console.log(issue.description); // TypeScript error - not selected

Field Selection with Lists

Field selection works the same way for list operations:

const characters = await client.character.list({
  fieldList: ['id', 'name', 'image', 'publisher'],
  filter: { name: 'Spider-Man' },
});

characters.results.forEach((character) => {
  console.log(character.name); // Available
  console.log(character.image); // Available
  console.log(character.description); // TypeScript error
});

Why Use Field Selection?

1. Smaller responses — The API only returns the fields you request, reducing bandwidth
2. Type safety — TypeScript prevents you from accessing fields that weren’t requested
3. Better IntelliSense — Auto-completion only shows available fields
4. Compile-time validation — Catch mistakes before runtime