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ResultTypeFromSelect

type ResultTypeFromSelect<TSelectObject> = IsAny<TSelectObject> extends true ? any : IsTrueRef<TSelectObject> extends true ? ExtractDirectSelectRef<TSelectObject> : WithoutRefBrand<Prettify<{ [K in keyof TSelectObject]: NeedsExtraction<TSelectObject[K]> extends true ? ExtractExpressionType<TSelectObject[K]> : TSelectObject[K] extends ToArrayWrapper<infer T> ? T[] : TSelectObject[K] extends ConcatToArrayWrapper<any> ? string : TSelectObject[K] extends MaterializeWrapper<infer T, infer IsSingle> ? IsSingle extends true ? (...) | (...) : (...)[] : (...)[(...)] extends { __brand: ...; _result?: ... } ? ResultTypeFromCaseWhen<(...)> : (...) extends (...) ? (...) : (...) }>>;

Defined in: packages/db/src/query/builder/types.ts:413

ResultTypeFromSelect - Infers the result type from a select object

This complex type transforms the input to select() into the actual TypeScript type that the query will return. It handles all the different kinds of values that can appear in a select clause:

Ref/RefProxy Extraction:

  • RefProxy<T> → T: Extracts the underlying type
  • Ref<T> | undefined → T | undefined: Preserves optionality
  • Ref<T> | null → T | null: Preserves nullability

Expression Types:

  • BasicExpression<T> → T: Function results like upper() → string
  • Aggregate<T> → T: Aggregation results like count() → number

JavaScript Literals (pass through as-is):

  • string → string: String literals remain strings
  • number → number: Numeric literals remain numbers
  • boolean → boolean: Boolean literals remain booleans
  • null → null: Explicit null remains null
  • undefined → undefined: Direct undefined values

Nested Objects (recursive):

  • Plain objects are recursively processed to handle nested projections
  • RefProxy objects are detected and their types extracted

Example transformation:

// Input:
{ id: Ref<number>, name: Ref<string>, status: 'active', count: 42, profile: { bio: Ref<string> } }

// Output:
{ id: number, name: string, status: 'active', count: 42, profile: { bio: string } }

Type Parameters

TSelectObject

TSelectObject

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