remove the magical UnionToIntersection type

kysely-org · Dec 30, 2021 · 0ca3b01 · 0ca3b01
1 parent a899c55
commit 0ca3b01
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Showing 8 changed files with 74 additions and 33 deletions.
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "kysely",
-  "version": "0.14.0",
+  "version": "0.14.1",
   "description": "Type safe SQL query builder",
   "repository": {
     "type": "git",

diff --git a/src/parser/reference-parser.ts b/src/parser/reference-parser.ts
@@ -11,7 +11,7 @@ import {
 import {
   AnyColumn,
   AnyColumnWithTable,
-  RowType,
+  ExtractColumnType,
   ValueType,
 } from '../util/type-utils.js'
 import { RawBuilder } from '../raw-builder/raw-builder.js'
@@ -58,8 +58,7 @@ export type ExtractTypeFromReferenceExpression<
 type ExtractTypeFromStringReference<
   DB,
   TB extends keyof DB,
-  RE extends string,
-  R = RowType<DB, TB>
+  RE extends string
 > = RE extends `${infer SC}.${infer T}.${infer C}`
   ? `${SC}.${T}` extends TB
     ? C extends keyof DB[`${SC}.${T}`]
@@ -72,8 +71,8 @@ type ExtractTypeFromStringReference<
       ? DB[T][C]
       : never
     : never
-  : RE extends keyof R
-  ? R[RE]
+  : RE extends AnyColumn<DB, TB>
+  ? ExtractColumnType<DB, TB, RE>
   : PrimitiveValue
 
 export function parseReferenceExpressionOrList(

diff --git a/src/parser/select-parser.ts b/src/parser/select-parser.ts
@@ -10,6 +10,7 @@ import {
   AnyAliasedColumnWithTable,
   AnyColumn,
   AnyColumnWithTable,
+  ExtractColumnType,
   RowType,
   ValueType,
 } from '../util/type-utils.js'
@@ -126,8 +127,7 @@ type ExtractTypeFromStringSelectExpression<
   DB,
   TB extends keyof DB,
   SE extends string,
-  A extends keyof any,
-  R = RowType<DB, TB>
+  A extends keyof any
 > = SE extends `${infer SC}.${infer T}.${infer C} as ${infer RA}`
   ? RA extends A
     ? `${SC}.${T}` extends TB
@@ -146,8 +146,8 @@ type ExtractTypeFromStringSelectExpression<
     : never
   : SE extends `${infer C} as ${infer RA}`
   ? RA extends A
-    ? C extends keyof R
-      ? R[C]
+    ? C extends AnyColumn<DB, TB>
+      ? ExtractColumnType<DB, TB, C>
       : never
     : never
   : SE extends `${infer SC}.${infer T}.${infer C}`
@@ -167,8 +167,8 @@ type ExtractTypeFromStringSelectExpression<
       : never
     : never
   : SE extends A
-  ? SE extends keyof R
-    ? R[SE]
+  ? SE extends AnyColumn<DB, TB>
+    ? ExtractColumnType<DB, TB, SE>
     : never
   : never
 

diff --git a/src/query-builder/on-conflict-builder.ts b/src/query-builder/on-conflict-builder.ts
@@ -18,7 +18,6 @@ import {
   MutationObject,
   parseUpdateObject,
 } from '../parser/update-set-parser.js'
-import { RawBuilder } from '../raw-builder/raw-builder.js'
 import { freeze } from '../util/object-utils.js'
 import { preventAwait } from '../util/prevent-await.js'
 import { AnyColumn, AnyRawBuilder } from '../util/type-utils.js'
@@ -308,7 +307,10 @@ export class OnConflictBuilder<DB, TB extends keyof DB>
    */
   doUpdateSet(
     updates: MutationObject<DB, TB>
-  ): OnConflictUpdateBuilder<DB & Record<'excluded', DB[TB]>, TB | 'excluded'> {
+  ): OnConflictUpdateBuilder<
+    { [K in keyof DB | 'excluded']: K extends keyof DB ? DB[K] : DB[TB] },
+    TB | 'excluded'
+  > {
     return new OnConflictUpdateBuilder({
       ...this.#props,
       onConflictNode: OnConflictNode.cloneWith(this.#props.onConflictNode, {

diff --git a/src/util/type-utils.ts b/src/util/type-utils.ts
@@ -44,17 +44,11 @@ export type ValueType<T> = T[keyof T]
  * // Row == Person & Movie
  * ```
  */
-export type RowType<DB, TB extends keyof DB> = UnionToIntersection<DB[TB]>
-
-/**
- * Evil typescript magic to convert a union type `A | B | C` into an
- * intersection type `A & B & C`.
- */
-type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (
-  k: infer I
-) => void
-  ? I
-  : never
+export type RowType<DB, TB extends keyof DB> = {
+  [C in AnyColumn<DB, TB>]: {
+    [T in TB]: C extends keyof DB[T] ? DB[T][C] : never
+  }[TB]
+}
 
 /**
  * Given a database type and a union of table names in that db, returns
@@ -92,6 +86,13 @@ export type AnyColumn<DB, TB extends keyof DB> = {
 }[TB] &
   string
 
+/**
+ * Extracts a column type.
+ */
+export type ExtractColumnType<DB, TB extends keyof DB, C> = {
+  [T in TB]: C extends keyof DB[T] ? DB[T][C] : never
+}[TB]
+
 /**
  * Given a database type and a union of table names in that db, returns
  * a union type with all possible `table`.`column` combinations.

diff --git a/test/src/test-setup.ts b/test/src/test-setup.ts
@@ -312,9 +312,9 @@ async function insertToysForPet(
     .executeTakeFirst()
 }
 
-async function insert(
+async function insert<TB extends keyof Database>(
   dialect: BuiltInDialect,
-  qb: InsertQueryBuilder<Database, keyof Database, InsertResult>
+  qb: InsertQueryBuilder<Database, TB, InsertResult>
 ): Promise<number> {
   if (dialect === 'postgres') {
     const { id } = await qb.returning('id').executeTakeFirstOrThrow()

diff --git a/test/typings/index.test-d.ts b/test/typings/index.test-d.ts
@@ -396,7 +396,16 @@ async function testJoin(db: Kysely<Database>) {
     .selectAll()
     .execute()
 
-  expectType<(Person & Movie)[]>(r1)
+  expectType<
+    {
+      id: number | string
+      first_name: string
+      last_name: string | null
+      age: number
+      gender: 'male' | 'female' | 'other'
+      stars: number
+    }[]
+  >(r1)
 
   const r2 = await db
     .selectFrom('person')
@@ -443,7 +452,17 @@ async function testJoin(db: Kysely<Database>) {
     .selectAll()
     .executeTakeFirstOrThrow()
 
-  expectType<Person & Nullable<Pet> & Nullable<Movie>>(r5)
+  expectType<{
+    id: number | string | null
+    first_name: string
+    last_name: string | null
+    age: number
+    gender: 'male' | 'female' | 'other'
+    name: string | null
+    species: 'dog' | 'cat' | null
+    owner_id: number | null
+    stars: number | null
+  }>(r5)
 
   const r6 = await db
     .selectFrom('person')
@@ -452,7 +471,17 @@ async function testJoin(db: Kysely<Database>) {
     .selectAll()
     .executeTakeFirstOrThrow()
 
-  expectType<Nullable<Person> & Nullable<Pet> & Movie>(r6)
+  expectType<{
+    id: number | string | null
+    first_name: string | null
+    last_name: string | null
+    age: number | null
+    gender: 'male' | 'female' | 'other' | null
+    name: string | null
+    species: 'dog' | 'cat' | null
+    owner_id: number | null
+    stars: number
+  }>(r6)
 
   const r7 = await db
     .selectFrom('person')
@@ -461,7 +490,17 @@ async function testJoin(db: Kysely<Database>) {
     .selectAll()
     .executeTakeFirstOrThrow()
 
-  expectType<Nullable<Person> & Nullable<Pet> & Nullable<Movie>>(r7)
+  expectType<{
+    id: number | string | null
+    first_name: string | null
+    last_name: string | null
+    age: number | null
+    gender: 'male' | 'female' | 'other' | null
+    name: string | null
+    species: 'dog' | 'cat' | null
+    owner_id: number | null
+    stars: number | null
+  }>(r7)
 
   // Refer to table that's not joined
   expectError(